Update src/secp256k1 subtree to upstream libsecp256k1

42 files changed, 2928 insertions, 284 deletions

diff --git a/src/secp256k1/.gitignore b/src/secp256k1/.gitignore
index cb4331aa90..ccdef02b29 100644
--- a/src/secp256k1/.gitignore
+++ b/src/secp256k1/.gitignore
@@ -1,9 +1,9 @@
 bench_inv
 bench_ecdh
 bench_ecmult
+bench_schnorrsig
 bench_sign
 bench_verify
-bench_schnorr_verify
 bench_recover
 bench_internal
 tests
@@ -31,6 +31,8 @@ libtool
 *.lo
 *.o
 *~
+*.log
+*.trs
 src/libsecp256k1-config.h
 src/libsecp256k1-config.h.in
 src/ecmult_static_context.h
diff --git a/src/secp256k1/.travis.yml b/src/secp256k1/.travis.yml
index a6ad6fb27e..e1a88c4051 100644
--- a/src/secp256k1/.travis.yml
+++ b/src/secp256k1/.travis.yml
@@ -17,19 +17,19 @@ compiler:
   - gcc
 env:
   global:
-    - FIELD=auto  BIGNUM=auto  SCALAR=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ECMULTGENPRECISION=auto  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  RECOVERY=no  EXPERIMENTAL=no CTIMETEST=yes BENCH=yes ITERS=2
+    - WIDEMUL=auto  BIGNUM=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ECMULTGENPRECISION=auto  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  RECOVERY=no SCHNORRSIG=no EXPERIMENTAL=no CTIMETEST=yes BENCH=yes ITERS=2
   matrix:
-    - SCALAR=32bit    RECOVERY=yes
-    - SCALAR=32bit    FIELD=32bit       ECDH=yes  EXPERIMENTAL=yes
-    - SCALAR=64bit
-    - FIELD=64bit     RECOVERY=yes
-    - FIELD=64bit     ENDOMORPHISM=yes
-    - FIELD=64bit     ENDOMORPHISM=yes  ECDH=yes EXPERIMENTAL=yes
-    - FIELD=64bit                       ASM=x86_64
-    - FIELD=64bit     ENDOMORPHISM=yes  ASM=x86_64
-    - FIELD=32bit     ENDOMORPHISM=yes
+    - WIDEMUL=int64   RECOVERY=yes
+    - WIDEMUL=int64   ECDH=yes  EXPERIMENTAL=yes SCHNORRSIG=yes
+    - WIDEMUL=int64   ENDOMORPHISM=yes
+    - WIDEMUL=int128
+    - WIDEMUL=int128  RECOVERY=yes EXPERIMENTAL=yes SCHNORRSIG=yes
+    - WIDEMUL=int128  ENDOMORPHISM=yes
+    - WIDEMUL=int128  ENDOMORPHISM=yes  ECDH=yes EXPERIMENTAL=yes SCHNORRSIG=yes
+    - WIDEMUL=int128                    ASM=x86_64
+    - WIDEMUL=int128  ENDOMORPHISM=yes  ASM=x86_64
     - BIGNUM=no
-    - BIGNUM=no       ENDOMORPHISM=yes RECOVERY=yes EXPERIMENTAL=yes
+    - BIGNUM=no       ENDOMORPHISM=yes RECOVERY=yes EXPERIMENTAL=yes SCHNORRSIG=yes
     - BIGNUM=no       STATICPRECOMPUTATION=no
     - BUILD=distcheck CTIMETEST= BENCH=
     - CPPFLAGS=-DDETERMINISTIC
@@ -83,6 +83,10 @@ matrix:
             - valgrind
             - libtool-bin
             - libc6-dbg:i386
+    # S390x build (big endian system)
+    - compiler: gcc
+      env: HOST=s390x-unknown-linux-gnu ECDH=yes RECOVERY=yes EXPERIMENTAL=yes CTIMETEST=
+      arch: s390x
 
 # We use this to install macOS dependencies instead of the built in `homebrew` plugin,
 # because in xcode earlier than 11 they have a bug requiring updating the system which overall takes ~8 minutes.
diff --git a/src/secp256k1/Makefile.am b/src/secp256k1/Makefile.am
index d8c1c79e8c..023fa6067f 100644
--- a/src/secp256k1/Makefile.am
+++ b/src/secp256k1/Makefile.am
@@ -34,9 +34,11 @@ noinst_HEADERS += src/field_5x52.h
 noinst_HEADERS += src/field_5x52_impl.h
 noinst_HEADERS += src/field_5x52_int128_impl.h
 noinst_HEADERS += src/field_5x52_asm_impl.h
+noinst_HEADERS += src/assumptions.h
 noinst_HEADERS += src/util.h
 noinst_HEADERS += src/scratch.h
 noinst_HEADERS += src/scratch_impl.h
+noinst_HEADERS += src/selftest.h
 noinst_HEADERS += src/testrand.h
 noinst_HEADERS += src/testrand_impl.h
 noinst_HEADERS += src/hash.h
@@ -99,7 +101,7 @@ if VALGRIND_ENABLED
 tests_CPPFLAGS += -DVALGRIND
 noinst_PROGRAMS += valgrind_ctime_test
 valgrind_ctime_test_SOURCES = src/valgrind_ctime_test.c
-valgrind_ctime_test_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
+valgrind_ctime_test_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_LIBS) $(COMMON_LIB)
 endif
 if !ENABLE_COVERAGE
 tests_CPPFLAGS += -DVERIFY
@@ -152,3 +154,11 @@ endif
 if ENABLE_MODULE_RECOVERY
 include src/modules/recovery/Makefile.am.include
 endif
+
+if ENABLE_MODULE_EXTRAKEYS
+include src/modules/extrakeys/Makefile.am.include
+endif
+
+if ENABLE_MODULE_SCHNORRSIG
+include src/modules/schnorrsig/Makefile.am.include
+endif
diff --git a/src/secp256k1/TODO b/src/secp256k1/TODO
deleted file mode 100644
index a300e1c5eb..0000000000
--- a/src/secp256k1/TODO
+++ /dev/null
@@ -1,3 +0,0 @@
-* Unit tests for fieldelem/groupelem, including ones intended to
-  trigger fieldelem's boundary cases.
-* Complete constant-time operations for signing/keygen
diff --git a/src/secp256k1/build-aux/m4/bitcoin_secp.m4 b/src/secp256k1/build-aux/m4/bitcoin_secp.m4
index 1b2b71e6ab..57595f4499 100644
--- a/src/secp256k1/build-aux/m4/bitcoin_secp.m4
+++ b/src/secp256k1/build-aux/m4/bitcoin_secp.m4
@@ -1,8 +1,3 @@
-dnl libsecp25k1 helper checks
-AC_DEFUN([SECP_INT128_CHECK],[
-has_int128=$ac_cv_type___int128
-])
-
 dnl escape "$0x" below using the m4 quadrigaph @S|@, and escape it again with a \ for the shell.
 AC_DEFUN([SECP_64BIT_ASM_CHECK],[
 AC_MSG_CHECKING(for x86_64 assembly availability)
diff --git a/src/secp256k1/configure.ac b/src/secp256k1/configure.ac
index 6021b760b5..6fe8984f4d 100644
--- a/src/secp256k1/configure.ac
+++ b/src/secp256k1/configure.ac
@@ -136,20 +136,28 @@ AC_ARG_ENABLE(module_recovery,
     [enable_module_recovery=$enableval],
     [enable_module_recovery=no])
 
+AC_ARG_ENABLE(module_extrakeys,
+    AS_HELP_STRING([--enable-module-extrakeys],[enable extrakeys module (experimental)]),
+    [enable_module_extrakeys=$enableval],
+    [enable_module_extrakeys=no])
+
+AC_ARG_ENABLE(module_schnorrsig,
+    AS_HELP_STRING([--enable-module-schnorrsig],[enable schnorrsig module (experimental)]),
+    [enable_module_schnorrsig=$enableval],
+    [enable_module_schnorrsig=no])
+
 AC_ARG_ENABLE(external_default_callbacks,
     AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]),
     [use_external_default_callbacks=$enableval],
     [use_external_default_callbacks=no])
 
-AC_ARG_WITH([field], [AS_HELP_STRING([--with-field=64bit|32bit|auto],
-[finite field implementation to use [default=auto]])],[req_field=$withval], [req_field=auto])
+dnl Test-only override of the (autodetected by the C code) "widemul" setting.
+dnl Legal values are int64 (for [u]int64_t), int128 (for [unsigned] __int128), and auto (the default).
+AC_ARG_WITH([test-override-wide-multiply], [] ,[set_widemul=$withval], [set_widemul=auto])
 
 AC_ARG_WITH([bignum], [AS_HELP_STRING([--with-bignum=gmp|no|auto],
 [bignum implementation to use [default=auto]])],[req_bignum=$withval], [req_bignum=auto])
 
-AC_ARG_WITH([scalar], [AS_HELP_STRING([--with-scalar=64bit|32bit|auto],
-[scalar implementation to use [default=auto]])],[req_scalar=$withval], [req_scalar=auto])
-
 AC_ARG_WITH([asm], [AS_HELP_STRING([--with-asm=x86_64|arm|no|auto],
 [assembly optimizations to use (experimental: arm) [default=auto]])],[req_asm=$withval], [req_asm=auto])
 
@@ -170,8 +178,6 @@ AC_ARG_WITH([ecmult-gen-precision], [AS_HELP_STRING([--with-ecmult-gen-precision
 )],
 [req_ecmult_gen_precision=$withval], [req_ecmult_gen_precision=auto])
 
-AC_CHECK_TYPES([__int128])
-
 AC_CHECK_HEADER([valgrind/memcheck.h], [enable_valgrind=yes], [enable_valgrind=no], [])
 AM_CONDITIONAL([VALGRIND_ENABLED],[test "$enable_valgrind" = "yes"])
 
@@ -265,63 +271,6 @@ else
   esac
 fi
 
-if test x"$req_field" = x"auto"; then
-  if test x"set_asm" = x"x86_64"; then
-    set_field=64bit
-  fi
-  if test x"$set_field" = x; then
-    SECP_INT128_CHECK
-    if test x"$has_int128" = x"yes"; then
-      set_field=64bit
-    fi
-  fi
-  if test x"$set_field" = x; then
-    set_field=32bit
-  fi
-else
-  set_field=$req_field
-  case $set_field in
-  64bit)
-    if test x"$set_asm" != x"x86_64"; then
-      SECP_INT128_CHECK
-      if test x"$has_int128" != x"yes"; then
-        AC_MSG_ERROR([64bit field explicitly requested but neither __int128 support or x86_64 assembly available])
-      fi
-    fi
-    ;;
-  32bit)
-    ;;
-  *)
-    AC_MSG_ERROR([invalid field implementation selection])
-    ;;
-  esac
-fi
-
-if test x"$req_scalar" = x"auto"; then
-  SECP_INT128_CHECK
-  if test x"$has_int128" = x"yes"; then
-    set_scalar=64bit
-  fi
-  if test x"$set_scalar" = x; then
-    set_scalar=32bit
-  fi
-else
-  set_scalar=$req_scalar
-  case $set_scalar in
-  64bit)
-    SECP_INT128_CHECK
-    if test x"$has_int128" != x"yes"; then
-      AC_MSG_ERROR([64bit scalar explicitly requested but __int128 support not available])
-    fi
-    ;;
-  32bit)
-    ;;
-  *)
-    AC_MSG_ERROR([invalid scalar implementation selected])
-    ;;
-  esac
-fi
-
 if test x"$req_bignum" = x"auto"; then
   SECP_GMP_CHECK
   if test x"$has_gmp" = x"yes"; then
@@ -365,16 +314,18 @@ no)
   ;;
 esac
 
-# select field implementation
-case $set_field in
-64bit)
-  AC_DEFINE(USE_FIELD_5X52, 1, [Define this symbol to use the FIELD_5X52 implementation])
+# select wide multiplication implementation
+case $set_widemul in
+int128)
+  AC_DEFINE(USE_FORCE_WIDEMUL_INT128, 1, [Define this symbol to force the use of the (unsigned) __int128 based wide multiplication implementation])
+  ;;
+int64)
+  AC_DEFINE(USE_FORCE_WIDEMUL_INT64, 1, [Define this symbol to force the use of the (u)int64_t based wide multiplication implementation])
   ;;
-32bit)
-  AC_DEFINE(USE_FIELD_10X26, 1, [Define this symbol to use the FIELD_10X26 implementation])
+auto)
   ;;
 *)
-  AC_MSG_ERROR([invalid field implementation])
+  AC_MSG_ERROR([invalid wide multiplication implementation])
   ;;
 esac
 
@@ -396,19 +347,6 @@ no)
   ;;
 esac
 
-#select scalar implementation
-case $set_scalar in
-64bit)
-  AC_DEFINE(USE_SCALAR_4X64, 1, [Define this symbol to use the 4x64 scalar implementation])
-  ;;
-32bit)
-  AC_DEFINE(USE_SCALAR_8X32, 1, [Define this symbol to use the 8x32 scalar implementation])
-  ;;
-*)
-  AC_MSG_ERROR([invalid scalar implementation])
-  ;;
-esac
-
 #set ecmult window size
 if test x"$req_ecmult_window" = x"auto"; then
   set_ecmult_window=15
@@ -493,7 +431,16 @@ if test x"$enable_module_recovery" = x"yes"; then
   AC_DEFINE(ENABLE_MODULE_RECOVERY, 1, [Define this symbol to enable the ECDSA pubkey recovery module])
 fi
 
-AC_C_BIGENDIAN()
+if test x"$enable_module_schnorrsig" = x"yes"; then
+  AC_DEFINE(ENABLE_MODULE_SCHNORRSIG, 1, [Define this symbol to enable the schnorrsig module])
+  enable_module_extrakeys=yes
+fi
+
+# Test if extrakeys is set after the schnorrsig module to allow the schnorrsig
+# module to set enable_module_extrakeys=yes
+if test x"$enable_module_extrakeys" = x"yes"; then
+  AC_DEFINE(ENABLE_MODULE_EXTRAKEYS, 1, [Define this symbol to enable the extrakeys module])
+fi
 
 if test x"$use_external_asm" = x"yes"; then
   AC_DEFINE(USE_EXTERNAL_ASM, 1, [Define this symbol if an external (non-inline) assembly implementation is used])
@@ -508,11 +455,19 @@ if test x"$enable_experimental" = x"yes"; then
   AC_MSG_NOTICE([WARNING: experimental build])
   AC_MSG_NOTICE([Experimental features do not have stable APIs or properties, and may not be safe for production use.])
   AC_MSG_NOTICE([Building ECDH module: $enable_module_ecdh])
+  AC_MSG_NOTICE([Building extrakeys module: $enable_module_extrakeys])
+  AC_MSG_NOTICE([Building schnorrsig module: $enable_module_schnorrsig])
   AC_MSG_NOTICE([******])
 else
   if test x"$enable_module_ecdh" = x"yes"; then
     AC_MSG_ERROR([ECDH module is experimental. Use --enable-experimental to allow.])
   fi
+  if test x"$enable_module_extrakeys" = x"yes"; then
+    AC_MSG_ERROR([extrakeys module is experimental. Use --enable-experimental to allow.])
+  fi
+  if test x"$enable_module_schnorrsig" = x"yes"; then
+    AC_MSG_ERROR([schnorrsig module is experimental. Use --enable-experimental to allow.])
+  fi
   if test x"$set_asm" = x"arm"; then
     AC_MSG_ERROR([ARM assembly optimization is experimental. Use --enable-experimental to allow.])
   fi
@@ -531,6 +486,8 @@ AM_CONDITIONAL([USE_BENCHMARK], [test x"$use_benchmark" = x"yes"])
 AM_CONDITIONAL([USE_ECMULT_STATIC_PRECOMPUTATION], [test x"$set_precomp" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_ECDH], [test x"$enable_module_ecdh" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_RECOVERY], [test x"$enable_module_recovery" = x"yes"])
+AM_CONDITIONAL([ENABLE_MODULE_EXTRAKEYS], [test x"$enable_module_extrakeys" = x"yes"])
+AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"])
 AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$use_external_asm" = x"yes"])
 AM_CONDITIONAL([USE_ASM_ARM], [test x"$set_asm" = x"arm"])
 
@@ -550,13 +507,17 @@ echo "  with benchmarks         = $use_benchmark"
 echo "  with coverage           = $enable_coverage"
 echo "  module ecdh             = $enable_module_ecdh"
 echo "  module recovery         = $enable_module_recovery"
+echo "  module extrakeys        = $enable_module_extrakeys"
+echo "  module schnorrsig       = $enable_module_schnorrsig"
 echo
 echo "  asm                     = $set_asm"
 echo "  bignum                  = $set_bignum"
-echo "  field                   = $set_field"
-echo "  scalar                  = $set_scalar"
 echo "  ecmult window size      = $set_ecmult_window"
 echo "  ecmult gen prec. bits   = $set_ecmult_gen_precision"
+dnl Hide test-only options unless they're used.
+if test x"$set_widemul" != xauto; then
+echo "  wide multiplication     = $set_widemul"
+fi
 echo
 echo "  valgrind                = $enable_valgrind"
 echo "  CC                      = $CC"
diff --git a/src/secp256k1/contrib/lax_der_parsing.c b/src/secp256k1/contrib/lax_der_parsing.c
index e177a0562d..f71db4b535 100644
--- a/src/secp256k1/contrib/lax_der_parsing.c
+++ b/src/secp256k1/contrib/lax_der_parsing.c
@@ -112,7 +112,6 @@ int ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_
         return 0;
     }
     spos = pos;
-    pos += slen;
 
     /* Ignore leading zeroes in R */
     while (rlen > 0 && input[rpos] == 0) {
diff --git a/src/secp256k1/contrib/travis.sh b/src/secp256k1/contrib/travis.sh
index 3909d16a27..b0b55b44b8 100755
--- a/src/secp256k1/contrib/travis.sh
+++ b/src/secp256k1/contrib/travis.sh
@@ -3,10 +3,6 @@
 set -e
 set -x
 
-if [ -n "$HOST" ]
-then
-    export USE_HOST="--host=$HOST"
-fi
 if [ "$HOST" = "i686-linux-gnu" ]
 then
     export CC="$CC -m32"
@@ -18,9 +14,11 @@ fi
 
 ./configure \
     --enable-experimental="$EXPERIMENTAL" --enable-endomorphism="$ENDOMORPHISM" \
-    --with-field="$FIELD" --with-bignum="$BIGNUM" --with-asm="$ASM" --with-scalar="$SCALAR" \
+    --with-test-override-wide-multiply="$WIDEMUL" --with-bignum="$BIGNUM" --with-asm="$ASM" \
     --enable-ecmult-static-precomputation="$STATICPRECOMPUTATION" --with-ecmult-gen-precision="$ECMULTGENPRECISION" \
-    --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" "$EXTRAFLAGS" "$USE_HOST"
+    --enable-module-ecdh="$ECDH" --enable-module-recovery="$RECOVERY" \
+    --enable-module-schnorrsig="$SCHNORRSIG" \
+    --host="$HOST" $EXTRAFLAGS
 
 if [ -n "$BUILD" ]
 then
diff --git a/src/secp256k1/include/secp256k1.h b/src/secp256k1/include/secp256k1.h
index 2ba2dca388..2178c8e2d6 100644
--- a/src/secp256k1/include/secp256k1.h
+++ b/src/secp256k1/include/secp256k1.h
@@ -134,7 +134,7 @@ typedef int (*secp256k1_nonce_function)(
 #  else
 #   define SECP256K1_API
 #  endif
-# elif defined(__GNUC__) && defined(SECP256K1_BUILD)
+# elif defined(__GNUC__) && (__GNUC__ >= 4) && defined(SECP256K1_BUILD)
 #  define SECP256K1_API __attribute__ ((visibility ("default")))
 # else
 #  define SECP256K1_API
diff --git a/src/secp256k1/include/secp256k1_extrakeys.h b/src/secp256k1/include/secp256k1_extrakeys.h
new file mode 100644
index 0000000000..0c5dff2c94
--- /dev/null
+++ b/src/secp256k1/include/secp256k1_extrakeys.h
@@ -0,0 +1,236 @@
+#ifndef SECP256K1_EXTRAKEYS_H
+#define SECP256K1_EXTRAKEYS_H
+
+#include "secp256k1.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Opaque data structure that holds a parsed and valid "x-only" public key.
+ *  An x-only pubkey encodes a point whose Y coordinate is even. It is
+ *  serialized using only its X coordinate (32 bytes). See BIP-340 for more
+ *  information about x-only pubkeys.
+ *
+ *  The exact representation of data inside is implementation defined and not
+ *  guaranteed to be portable between different platforms or versions. It is
+ *  however guaranteed to be 64 bytes in size, and can be safely copied/moved.
+ *  If you need to convert to a format suitable for storage, transmission, or
+ *  comparison, use secp256k1_xonly_pubkey_serialize and
+ *  secp256k1_xonly_pubkey_parse.
+ */
+typedef struct {
+    unsigned char data[64];
+} secp256k1_xonly_pubkey;
+
+/** Opaque data structure that holds a keypair consisting of a secret and a
+ *  public key.
+ *
+ *  The exact representation of data inside is implementation defined and not
+ *  guaranteed to be portable between different platforms or versions. It is
+ *  however guaranteed to be 96 bytes in size, and can be safely copied/moved.
+ */
+typedef struct {
+    unsigned char data[96];
+} secp256k1_keypair;
+
+/** Parse a 32-byte sequence into a xonly_pubkey object.
+ *
+ *  Returns: 1 if the public key was fully valid.
+ *           0 if the public key could not be parsed or is invalid.
+ *
+ *  Args:   ctx: a secp256k1 context object (cannot be NULL).
+ *  Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a
+ *               parsed version of input. If not, it's set to an invalid value.
+ *               (cannot be NULL).
+ *  In: input32: pointer to a serialized xonly_pubkey (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey* pubkey,
+    const unsigned char *input32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Serialize an xonly_pubkey object into a 32-byte sequence.
+ *
+ *  Returns: 1 always.
+ *
+ *  Args:     ctx: a secp256k1 context object (cannot be NULL).
+ *  Out: output32: a pointer to a 32-byte array to place the serialized key in
+ *                 (cannot be NULL).
+ *  In:    pubkey: a pointer to a secp256k1_xonly_pubkey containing an
+ *                 initialized public key (cannot be NULL).
+ */
+SECP256K1_API int secp256k1_xonly_pubkey_serialize(
+    const secp256k1_context* ctx,
+    unsigned char *output32,
+    const secp256k1_xonly_pubkey* pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey.
+ *
+ *  Returns: 1 if the public key was successfully converted
+ *           0 otherwise
+ *
+ *  Args:         ctx: pointer to a context object (cannot be NULL)
+ *  Out: xonly_pubkey: pointer to an x-only public key object for placing the
+ *                     converted public key (cannot be NULL)
+ *          pk_parity: pointer to an integer that will be set to 1 if the point
+ *                     encoded by xonly_pubkey is the negation of the pubkey and
+ *                     set to 0 otherwise. (can be NULL)
+ *  In:        pubkey: pointer to a public key that is converted (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubkey(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey *xonly_pubkey,
+    int *pk_parity,
+    const secp256k1_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
+
+/** Tweak an x-only public key by adding the generator multiplied with tweak32
+ *  to it.
+ *
+ *  Note that the resulting point can not in general be represented by an x-only
+ *  pubkey because it may have an odd Y coordinate. Instead, the output_pubkey
+ *  is a normal secp256k1_pubkey.
+ *
+ *  Returns: 0 if the arguments are invalid or the resulting public key would be
+ *           invalid (only when the tweak is the negation of the corresponding
+ *           secret key). 1 otherwise.
+ *
+ *  Args:           ctx: pointer to a context object initialized for verification
+ *                       (cannot be NULL)
+ *  Out:  output_pubkey: pointer to a public key to store the result. Will be set
+ *                       to an invalid value if this function returns 0 (cannot
+ *                       be NULL)
+ *  In: internal_pubkey: pointer to an x-only pubkey to apply the tweak to.
+ *                       (cannot be NULL).
+ *              tweak32: pointer to a 32-byte tweak. If the tweak is invalid
+ *                       according to secp256k1_ec_seckey_verify, this function
+ *                       returns 0. For uniformly random 32-byte arrays the
+ *                       chance of being invalid is negligible (around 1 in
+ *                       2^128) (cannot be NULL).
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add(
+    const secp256k1_context* ctx,
+    secp256k1_pubkey *output_pubkey,
+    const secp256k1_xonly_pubkey *internal_pubkey,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Checks that a tweaked pubkey is the result of calling
+ *  secp256k1_xonly_pubkey_tweak_add with internal_pubkey and tweak32.
+ *
+ *  The tweaked pubkey is represented by its 32-byte x-only serialization and
+ *  its pk_parity, which can both be obtained by converting the result of
+ *  tweak_add to a secp256k1_xonly_pubkey.
+ *
+ *  Note that this alone does _not_ verify that the tweaked pubkey is a
+ *  commitment. If the tweak is not chosen in a specific way, the tweaked pubkey
+ *  can easily be the result of a different internal_pubkey and tweak.
+ *
+ *  Returns: 0 if the arguments are invalid or the tweaked pubkey is not the
+ *           result of tweaking the internal_pubkey with tweak32. 1 otherwise.
+ *  Args:            ctx: pointer to a context object initialized for verification
+ *                       (cannot be NULL)
+ *  In: tweaked_pubkey32: pointer to a serialized xonly_pubkey (cannot be NULL)
+ *     tweaked_pk_parity: the parity of the tweaked pubkey (whose serialization
+ *                        is passed in as tweaked_pubkey32). This must match the
+ *                        pk_parity value that is returned when calling
+ *                        secp256k1_xonly_pubkey with the tweaked pubkey, or
+ *                        this function will fail.
+ *       internal_pubkey: pointer to an x-only public key object to apply the
+ *                        tweak to (cannot be NULL)
+ *               tweak32: pointer to a 32-byte tweak (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add_check(
+    const secp256k1_context* ctx,
+    const unsigned char *tweaked_pubkey32,
+    int tweaked_pk_parity,
+    const secp256k1_xonly_pubkey *internal_pubkey,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+
+/** Compute the keypair for a secret key.
+ *
+ *  Returns: 1: secret was valid, keypair is ready to use
+ *           0: secret was invalid, try again with a different secret
+ *  Args:    ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ *  Out: keypair: pointer to the created keypair (cannot be NULL)
+ *  In:   seckey: pointer to a 32-byte secret key (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create(
+    const secp256k1_context* ctx,
+    secp256k1_keypair *keypair,
+    const unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Get the public key from a keypair.
+ *
+ *  Returns: 0 if the arguments are invalid. 1 otherwise.
+ *  Args:    ctx: pointer to a context object (cannot be NULL)
+ *  Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to
+ *               the keypair public key. If not, it's set to an invalid value.
+ *               (cannot be NULL)
+ *  In: keypair: pointer to a keypair (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub(
+    const secp256k1_context* ctx,
+    secp256k1_pubkey *pubkey,
+    const secp256k1_keypair *keypair
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Get the x-only public key from a keypair.
+ *
+ *  This is the same as calling secp256k1_keypair_pub and then
+ *  secp256k1_xonly_pubkey_from_pubkey.
+ *
+ *  Returns: 0 if the arguments are invalid. 1 otherwise.
+ *  Args:   ctx: pointer to a context object (cannot be NULL)
+ *  Out: pubkey: pointer to an xonly_pubkey object. If 1 is returned, it is set
+ *               to the keypair public key after converting it to an
+ *               xonly_pubkey. If not, it's set to an invalid value (cannot be
+ *               NULL).
+ *    pk_parity: pointer to an integer that will be set to the pk_parity
+ *               argument of secp256k1_xonly_pubkey_from_pubkey (can be NULL).
+ *  In: keypair: pointer to a keypair (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_pub(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey *pubkey,
+    int *pk_parity,
+    const secp256k1_keypair *keypair
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
+
+/** Tweak a keypair by adding tweak32 to the secret key and updating the public
+ *  key accordingly.
+ *
+ *  Calling this function and then secp256k1_keypair_pub results in the same
+ *  public key as calling secp256k1_keypair_xonly_pub and then
+ *  secp256k1_xonly_pubkey_tweak_add.
+ *
+ *  Returns: 0 if the arguments are invalid or the resulting keypair would be
+ *           invalid (only when the tweak is the negation of the keypair's
+ *           secret key). 1 otherwise.
+ *
+ *  Args:       ctx: pointer to a context object initialized for verification
+ *                   (cannot be NULL)
+ *  In/Out: keypair: pointer to a keypair to apply the tweak to. Will be set to
+ *                   an invalid value if this function returns 0 (cannot be
+ *                   NULL).
+ *  In:     tweak32: pointer to a 32-byte tweak. If the tweak is invalid according
+ *                   to secp256k1_ec_seckey_verify, this function returns 0. For
+ *                   uniformly random 32-byte arrays the chance of being invalid
+ *                   is negligible (around 1 in 2^128) (cannot be NULL).
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_tweak_add(
+    const secp256k1_context* ctx,
+    secp256k1_keypair *keypair,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SECP256K1_EXTRAKEYS_H */
diff --git a/src/secp256k1/include/secp256k1_schnorrsig.h b/src/secp256k1/include/secp256k1_schnorrsig.h
new file mode 100644
index 0000000000..0150cd3395
--- /dev/null
+++ b/src/secp256k1/include/secp256k1_schnorrsig.h
@@ -0,0 +1,111 @@
+#ifndef SECP256K1_SCHNORRSIG_H
+#define SECP256K1_SCHNORRSIG_H
+
+#include "secp256k1.h"
+#include "secp256k1_extrakeys.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** This module implements a variant of Schnorr signatures compliant with
+ *  Bitcoin Improvement Proposal 340 "Schnorr Signatures for secp256k1"
+ *  (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
+ */
+
+/** A pointer to a function to deterministically generate a nonce.
+ *
+ *  Same as secp256k1_nonce function with the exception of accepting an
+ *  additional pubkey argument and not requiring an attempt argument. The pubkey
+ *  argument can protect signature schemes with key-prefixed challenge hash
+ *  inputs against reusing the nonce when signing with the wrong precomputed
+ *  pubkey.
+ *
+ *  Returns: 1 if a nonce was successfully generated. 0 will cause signing to
+ *           return an error.
+ *  Out:     nonce32:   pointer to a 32-byte array to be filled by the function.
+ *  In:      msg32:     the 32-byte message hash being verified (will not be NULL)
+ *           key32:     pointer to a 32-byte secret key (will not be NULL)
+ *      xonly_pk32:     the 32-byte serialized xonly pubkey corresponding to key32
+ *                      (will not be NULL)
+ *           algo16:    pointer to a 16-byte array describing the signature
+ *                      algorithm (will not be NULL).
+ *           data:      Arbitrary data pointer that is passed through.
+ *
+ *  Except for test cases, this function should compute some cryptographic hash of
+ *  the message, the key, the pubkey, the algorithm description, and data.
+ */
+typedef int (*secp256k1_nonce_function_hardened)(
+    unsigned char *nonce32,
+    const unsigned char *msg32,
+    const unsigned char *key32,
+    const unsigned char *xonly_pk32,
+    const unsigned char *algo16,
+    void *data
+);
+
+/** An implementation of the nonce generation function as defined in Bitcoin
+ *  Improvement Proposal 340 "Schnorr Signatures for secp256k1"
+ *  (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
+ *
+ *  If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
+ *  auxiliary random data as defined in BIP-340. If the data pointer is NULL,
+ *  schnorrsig_sign does not produce BIP-340 compliant signatures. The algo16
+ *  argument must be non-NULL, otherwise the function will fail and return 0.
+ *  The hash will be tagged with algo16 after removing all terminating null
+ *  bytes. Therefore, to create BIP-340 compliant signatures, algo16 must be set
+ *  to "BIP0340/nonce\0\0\0"
+ */
+SECP256K1_API extern const secp256k1_nonce_function_hardened secp256k1_nonce_function_bip340;
+
+/** Create a Schnorr signature.
+ *
+ *  Does _not_ strictly follow BIP-340 because it does not verify the resulting
+ *  signature. Instead, you can manually use secp256k1_schnorrsig_verify and
+ *  abort if it fails.
+ *
+ *  Otherwise BIP-340 compliant if the noncefp argument is NULL or
+ *  secp256k1_nonce_function_bip340 and the ndata argument is 32-byte auxiliary
+ *  randomness.
+ *
+ *  Returns 1 on success, 0 on failure.
+ *  Args:    ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ *  Out:   sig64: pointer to a 64-byte array to store the serialized signature (cannot be NULL)
+ *  In:    msg32: the 32-byte message being signed (cannot be NULL)
+ *       keypair: pointer to an initialized keypair (cannot be NULL)
+ *       noncefp: pointer to a nonce generation function. If NULL, secp256k1_nonce_function_bip340 is used
+ *         ndata: pointer to arbitrary data used by the nonce generation
+ *                function (can be NULL). If it is non-NULL and
+ *                secp256k1_nonce_function_bip340 is used, then ndata must be a
+ *                pointer to 32-byte auxiliary randomness as per BIP-340.
+ */
+SECP256K1_API int secp256k1_schnorrsig_sign(
+    const secp256k1_context* ctx,
+    unsigned char *sig64,
+    const unsigned char *msg32,
+    const secp256k1_keypair *keypair,
+    secp256k1_nonce_function_hardened noncefp,
+    void *ndata
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Verify a Schnorr signature.
+ *
+ *  Returns: 1: correct signature
+ *           0: incorrect signature
+ *  Args:    ctx: a secp256k1 context object, initialized for verification.
+ *  In:    sig64: pointer to the 64-byte signature to verify (cannot be NULL)
+ *         msg32: the 32-byte message being verified (cannot be NULL)
+ *        pubkey: pointer to an x-only public key to verify with (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorrsig_verify(
+    const secp256k1_context* ctx,
+    const unsigned char *sig64,
+    const unsigned char *msg32,
+    const secp256k1_xonly_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SECP256K1_SCHNORRSIG_H */
diff --git a/src/secp256k1/src/assumptions.h b/src/secp256k1/src/assumptions.h
new file mode 100644
index 0000000000..f9d4e8e793
--- /dev/null
+++ b/src/secp256k1/src/assumptions.h
@@ -0,0 +1,74 @@
+/**********************************************************************
+ * Copyright (c) 2020 Pieter Wuille                                   *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef SECP256K1_ASSUMPTIONS_H
+#define SECP256K1_ASSUMPTIONS_H
+
+#include "util.h"
+
+/* This library, like most software, relies on a number of compiler implementation defined (but not undefined)
+   behaviours. Although the behaviours we require are essentially universal we test them specifically here to
+   reduce the odds of experiencing an unwelcome surprise.
+*/
+
+struct secp256k1_assumption_checker {
+    /* This uses a trick to implement a static assertion in C89: a type with an array of negative size is not
+       allowed. */
+    int dummy_array[(
+        /* Bytes are 8 bits. */
+        CHAR_BIT == 8 &&
+
+        /* Conversions from unsigned to signed outside of the bounds of the signed type are
+           implementation-defined. Verify that they function as reinterpreting the lower
+           bits of the input in two's complement notation. Do this for conversions:
+           - from uint(N)_t to int(N)_t with negative result
+           - from uint(2N)_t to int(N)_t with negative result
+           - from int(2N)_t to int(N)_t with negative result
+           - from int(2N)_t to int(N)_t with positive result */
+
+        /* To int8_t. */
+        ((int8_t)(uint8_t)0xAB == (int8_t)-(int8_t)0x55) &&
+        ((int8_t)(uint16_t)0xABCD == (int8_t)-(int8_t)0x33) &&
+        ((int8_t)(int16_t)(uint16_t)0xCDEF == (int8_t)(uint8_t)0xEF) &&
+        ((int8_t)(int16_t)(uint16_t)0x9234 == (int8_t)(uint8_t)0x34) &&
+
+        /* To int16_t. */
+        ((int16_t)(uint16_t)0xBCDE == (int16_t)-(int16_t)0x4322) &&
+        ((int16_t)(uint32_t)0xA1B2C3D4 == (int16_t)-(int16_t)0x3C2C) &&
+        ((int16_t)(int32_t)(uint32_t)0xC1D2E3F4 == (int16_t)(uint16_t)0xE3F4) &&
+        ((int16_t)(int32_t)(uint32_t)0x92345678 == (int16_t)(uint16_t)0x5678) &&
+
+        /* To int32_t. */
+        ((int32_t)(uint32_t)0xB2C3D4E5 == (int32_t)-(int32_t)0x4D3C2B1B) &&
+        ((int32_t)(uint64_t)0xA123B456C789D012ULL == (int32_t)-(int32_t)0x38762FEE) &&
+        ((int32_t)(int64_t)(uint64_t)0xC1D2E3F4A5B6C7D8ULL == (int32_t)(uint32_t)0xA5B6C7D8) &&
+        ((int32_t)(int64_t)(uint64_t)0xABCDEF0123456789ULL == (int32_t)(uint32_t)0x23456789) &&
+
+        /* To int64_t. */
+        ((int64_t)(uint64_t)0xB123C456D789E012ULL == (int64_t)-(int64_t)0x4EDC3BA928761FEEULL) &&
+#if defined(SECP256K1_WIDEMUL_INT128)
+        ((int64_t)(((uint128_t)0xA1234567B8901234ULL << 64) + 0xC5678901D2345678ULL) == (int64_t)-(int64_t)0x3A9876FE2DCBA988ULL) &&
+        (((int64_t)(int128_t)(((uint128_t)0xB1C2D3E4F5A6B7C8ULL << 64) + 0xD9E0F1A2B3C4D5E6ULL)) == (int64_t)(uint64_t)0xD9E0F1A2B3C4D5E6ULL) &&
+        (((int64_t)(int128_t)(((uint128_t)0xABCDEF0123456789ULL << 64) + 0x0123456789ABCDEFULL)) == (int64_t)(uint64_t)0x0123456789ABCDEFULL) &&
+
+        /* To int128_t. */
+        ((int128_t)(((uint128_t)0xB1234567C8901234ULL << 64) + 0xD5678901E2345678ULL) == (int128_t)(-(int128_t)0x8E1648B3F50E80DCULL * 0x8E1648B3F50E80DDULL + 0x5EA688D5482F9464ULL)) &&
+#endif
+
+        /* Right shift on negative signed values is implementation defined. Verify that it
+           acts as a right shift in two's complement with sign extension (i.e duplicating
+           the top bit into newly added bits). */
+        ((((int8_t)0xE8) >> 2) == (int8_t)(uint8_t)0xFA) &&
+        ((((int16_t)0xE9AC) >> 4) == (int16_t)(uint16_t)0xFE9A) &&
+        ((((int32_t)0x937C918A) >> 9) == (int32_t)(uint32_t)0xFFC9BE48) &&
+        ((((int64_t)0xA8B72231DF9CF4B9ULL) >> 19) == (int64_t)(uint64_t)0xFFFFF516E4463BF3ULL) &&
+#if defined(SECP256K1_WIDEMUL_INT128)
+        ((((int128_t)(((uint128_t)0xCD833A65684A0DBCULL << 64) + 0xB349312F71EA7637ULL)) >> 39) == (int128_t)(((uint128_t)0xFFFFFFFFFF9B0674ULL << 64) + 0xCAD0941B79669262ULL)) &&
+#endif
+    1) * 2 - 1];
+};
+
+#endif /* SECP256K1_ASSUMPTIONS_H */
diff --git a/src/secp256k1/src/basic-config.h b/src/secp256k1/src/basic-config.h
index e9be39d4ca..83dbe6f25b 100644
--- a/src/secp256k1/src/basic-config.h
+++ b/src/secp256k1/src/basic-config.h
@@ -14,23 +14,20 @@
 #undef USE_ENDOMORPHISM
 #undef USE_EXTERNAL_ASM
 #undef USE_EXTERNAL_DEFAULT_CALLBACKS
-#undef USE_FIELD_10X26
-#undef USE_FIELD_5X52
 #undef USE_FIELD_INV_BUILTIN
 #undef USE_FIELD_INV_NUM
 #undef USE_NUM_GMP
 #undef USE_NUM_NONE
-#undef USE_SCALAR_4X64
-#undef USE_SCALAR_8X32
 #undef USE_SCALAR_INV_BUILTIN
 #undef USE_SCALAR_INV_NUM
+#undef USE_FORCE_WIDEMUL_INT64
+#undef USE_FORCE_WIDEMUL_INT128
 #undef ECMULT_WINDOW_SIZE
 
 #define USE_NUM_NONE 1
 #define USE_FIELD_INV_BUILTIN 1
 #define USE_SCALAR_INV_BUILTIN 1
-#define USE_FIELD_10X26 1
-#define USE_SCALAR_8X32 1
+#define USE_WIDEMUL_64 1
 #define ECMULT_WINDOW_SIZE 15
 
 #endif /* USE_BASIC_CONFIG */
diff --git a/src/secp256k1/src/bench_internal.c b/src/secp256k1/src/bench_internal.c
index 20759127d3..9687fe4482 100644
--- a/src/secp256k1/src/bench_internal.c
+++ b/src/secp256k1/src/bench_internal.c
@@ -7,6 +7,7 @@
 
 #include "include/secp256k1.h"
 
+#include "assumptions.h"
 #include "util.h"
 #include "hash_impl.h"
 #include "num_impl.h"
@@ -19,10 +20,10 @@
 #include "secp256k1.c"
 
 typedef struct {
-    secp256k1_scalar scalar_x, scalar_y;
-    secp256k1_fe fe_x, fe_y;
-    secp256k1_ge ge_x, ge_y;
-    secp256k1_gej gej_x, gej_y;
+    secp256k1_scalar scalar[2];
+    secp256k1_fe fe[4];
+    secp256k1_ge ge[2];
+    secp256k1_gej gej[2];
     unsigned char data[64];
     int wnaf[256];
 } bench_inv;
@@ -30,30 +31,53 @@ typedef struct {
 void bench_setup(void* arg) {
     bench_inv *data = (bench_inv*)arg;
 
-    static const unsigned char init_x[32] = {
-        0x02, 0x03, 0x05, 0x07, 0x0b, 0x0d, 0x11, 0x13,
-        0x17, 0x1d, 0x1f, 0x25, 0x29, 0x2b, 0x2f, 0x35,
-        0x3b, 0x3d, 0x43, 0x47, 0x49, 0x4f, 0x53, 0x59,
-        0x61, 0x65, 0x67, 0x6b, 0x6d, 0x71, 0x7f, 0x83
+    static const unsigned char init[4][32] = {
+        /* Initializer for scalar[0], fe[0], first half of data, the X coordinate of ge[0],
+           and the (implied affine) X coordinate of gej[0]. */
+        {
+            0x02, 0x03, 0x05, 0x07, 0x0b, 0x0d, 0x11, 0x13,
+            0x17, 0x1d, 0x1f, 0x25, 0x29, 0x2b, 0x2f, 0x35,
+            0x3b, 0x3d, 0x43, 0x47, 0x49, 0x4f, 0x53, 0x59,
+            0x61, 0x65, 0x67, 0x6b, 0x6d, 0x71, 0x7f, 0x83
+        },
+        /* Initializer for scalar[1], fe[1], first half of data, the X coordinate of ge[1],
+           and the (implied affine) X coordinate of gej[1]. */
+        {
+            0x82, 0x83, 0x85, 0x87, 0x8b, 0x8d, 0x81, 0x83,
+            0x97, 0xad, 0xaf, 0xb5, 0xb9, 0xbb, 0xbf, 0xc5,
+            0xdb, 0xdd, 0xe3, 0xe7, 0xe9, 0xef, 0xf3, 0xf9,
+            0x11, 0x15, 0x17, 0x1b, 0x1d, 0xb1, 0xbf, 0xd3
+        },
+        /* Initializer for fe[2] and the Z coordinate of gej[0]. */
+        {
+            0x3d, 0x2d, 0xef, 0xf4, 0x25, 0x98, 0x4f, 0x5d,
+            0xe2, 0xca, 0x5f, 0x41, 0x3f, 0x3f, 0xce, 0x44,
+            0xaa, 0x2c, 0x53, 0x8a, 0xc6, 0x59, 0x1f, 0x38,
+            0x38, 0x23, 0xe4, 0x11, 0x27, 0xc6, 0xa0, 0xe7
+        },
+        /* Initializer for fe[3] and the Z coordinate of gej[1]. */
+        {
+            0xbd, 0x21, 0xa5, 0xe1, 0x13, 0x50, 0x73, 0x2e,
+            0x52, 0x98, 0xc8, 0x9e, 0xab, 0x00, 0xa2, 0x68,
+            0x43, 0xf5, 0xd7, 0x49, 0x80, 0x72, 0xa7, 0xf3,
+            0xd7, 0x60, 0xe6, 0xab, 0x90, 0x92, 0xdf, 0xc5
+        }
     };
 
-    static const unsigned char init_y[32] = {
-        0x82, 0x83, 0x85, 0x87, 0x8b, 0x8d, 0x81, 0x83,
-        0x97, 0xad, 0xaf, 0xb5, 0xb9, 0xbb, 0xbf, 0xc5,
-        0xdb, 0xdd, 0xe3, 0xe7, 0xe9, 0xef, 0xf3, 0xf9,
-        0x11, 0x15, 0x17, 0x1b, 0x1d, 0xb1, 0xbf, 0xd3
-    };
-
-    secp256k1_scalar_set_b32(&data->scalar_x, init_x, NULL);
-    secp256k1_scalar_set_b32(&data->scalar_y, init_y, NULL);
-    secp256k1_fe_set_b32(&data->fe_x, init_x);
-    secp256k1_fe_set_b32(&data->fe_y, init_y);
-    CHECK(secp256k1_ge_set_xo_var(&data->ge_x, &data->fe_x, 0));
-    CHECK(secp256k1_ge_set_xo_var(&data->ge_y, &data->fe_y, 1));
-    secp256k1_gej_set_ge(&data->gej_x, &data->ge_x);
-    secp256k1_gej_set_ge(&data->gej_y, &data->ge_y);
-    memcpy(data->data, init_x, 32);
-    memcpy(data->data + 32, init_y, 32);
+    secp256k1_scalar_set_b32(&data->scalar[0], init[0], NULL);
+    secp256k1_scalar_set_b32(&data->scalar[1], init[1], NULL);
+    secp256k1_fe_set_b32(&data->fe[0], init[0]);
+    secp256k1_fe_set_b32(&data->fe[1], init[1]);
+    secp256k1_fe_set_b32(&data->fe[2], init[2]);
+    secp256k1_fe_set_b32(&data->fe[3], init[3]);
+    CHECK(secp256k1_ge_set_xo_var(&data->ge[0], &data->fe[0], 0));
+    CHECK(secp256k1_ge_set_xo_var(&data->ge[1], &data->fe[1], 1));
+    secp256k1_gej_set_ge(&data->gej[0], &data->ge[0]);
+    secp256k1_gej_rescale(&data->gej[0], &data->fe[2]);
+    secp256k1_gej_set_ge(&data->gej[1], &data->ge[1]);
+    secp256k1_gej_rescale(&data->gej[1], &data->fe[3]);
+    memcpy(data->data, init[0], 32);
+    memcpy(data->data + 32, init[1], 32);
 }
 
 void bench_scalar_add(void* arg, int iters) {
@@ -61,7 +85,7 @@ void bench_scalar_add(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        j += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(j <= iters);
 }
@@ -71,7 +95,7 @@ void bench_scalar_negate(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_negate(&data->scalar_x, &data->scalar_x);
+        secp256k1_scalar_negate(&data->scalar[0], &data->scalar[0]);
     }
 }
 
@@ -80,7 +104,7 @@ void bench_scalar_sqr(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_sqr(&data->scalar_x, &data->scalar_x);
+        secp256k1_scalar_sqr(&data->scalar[0], &data->scalar[0]);
     }
 }
 
@@ -89,7 +113,7 @@ void bench_scalar_mul(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_mul(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        secp256k1_scalar_mul(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
 }
 
@@ -99,8 +123,8 @@ void bench_scalar_split(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_split_lambda(&data->scalar_x, &data->scalar_y, &data->scalar_x);
-        j += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        secp256k1_scalar_split_lambda(&data->scalar[0], &data->scalar[1], &data->scalar[0]);
+        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(j <= iters);
 }
@@ -111,8 +135,8 @@ void bench_scalar_inverse(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_inverse(&data->scalar_x, &data->scalar_x);
-        j += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        secp256k1_scalar_inverse(&data->scalar[0], &data->scalar[0]);
+        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(j <= iters);
 }
@@ -122,8 +146,8 @@ void bench_scalar_inverse_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_scalar_inverse_var(&data->scalar_x, &data->scalar_x);
-        j += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        secp256k1_scalar_inverse_var(&data->scalar[0], &data->scalar[0]);
+        j += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(j <= iters);
 }
@@ -133,7 +157,7 @@ void bench_field_normalize(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_normalize(&data->fe_x);
+        secp256k1_fe_normalize(&data->fe[0]);
     }
 }
 
@@ -142,7 +166,7 @@ void bench_field_normalize_weak(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_normalize_weak(&data->fe_x);
+        secp256k1_fe_normalize_weak(&data->fe[0]);
     }
 }
 
@@ -151,7 +175,7 @@ void bench_field_mul(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_mul(&data->fe_x, &data->fe_x, &data->fe_y);
+        secp256k1_fe_mul(&data->fe[0], &data->fe[0], &data->fe[1]);
     }
 }
 
@@ -160,7 +184,7 @@ void bench_field_sqr(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_sqr(&data->fe_x, &data->fe_x);
+        secp256k1_fe_sqr(&data->fe[0], &data->fe[0]);
     }
 }
 
@@ -169,8 +193,8 @@ void bench_field_inverse(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_inv(&data->fe_x, &data->fe_x);
-        secp256k1_fe_add(&data->fe_x, &data->fe_y);
+        secp256k1_fe_inv(&data->fe[0], &data->fe[0]);
+        secp256k1_fe_add(&data->fe[0], &data->fe[1]);
     }
 }
 
@@ -179,8 +203,8 @@ void bench_field_inverse_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_fe_inv_var(&data->fe_x, &data->fe_x);
-        secp256k1_fe_add(&data->fe_x, &data->fe_y);
+        secp256k1_fe_inv_var(&data->fe[0], &data->fe[0]);
+        secp256k1_fe_add(&data->fe[0], &data->fe[1]);
     }
 }
 
@@ -190,9 +214,9 @@ void bench_field_sqrt(void* arg, int iters) {
     secp256k1_fe t;
 
     for (i = 0; i < iters; i++) {
-        t = data->fe_x;
-        j += secp256k1_fe_sqrt(&data->fe_x, &t);
-        secp256k1_fe_add(&data->fe_x, &data->fe_y);
+        t = data->fe[0];
+        j += secp256k1_fe_sqrt(&data->fe[0], &t);
+        secp256k1_fe_add(&data->fe[0], &data->fe[1]);
     }
     CHECK(j <= iters);
 }
@@ -202,7 +226,7 @@ void bench_group_double_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_gej_double_var(&data->gej_x, &data->gej_x, NULL);
+        secp256k1_gej_double_var(&data->gej[0], &data->gej[0], NULL);
     }
 }
 
@@ -211,7 +235,7 @@ void bench_group_add_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_gej_add_var(&data->gej_x, &data->gej_x, &data->gej_y, NULL);
+        secp256k1_gej_add_var(&data->gej[0], &data->gej[0], &data->gej[1], NULL);
     }
 }
 
@@ -220,7 +244,7 @@ void bench_group_add_affine(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_gej_add_ge(&data->gej_x, &data->gej_x, &data->ge_y);
+        secp256k1_gej_add_ge(&data->gej[0], &data->gej[0], &data->ge[1]);
     }
 }
 
@@ -229,7 +253,7 @@ void bench_group_add_affine_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        secp256k1_gej_add_ge_var(&data->gej_x, &data->gej_x, &data->ge_y, NULL);
+        secp256k1_gej_add_ge_var(&data->gej[0], &data->gej[0], &data->ge[1], NULL);
     }
 }
 
@@ -238,9 +262,37 @@ void bench_group_jacobi_var(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        j += secp256k1_gej_has_quad_y_var(&data->gej_x);
+        j += secp256k1_gej_has_quad_y_var(&data->gej[0]);
+        /* Vary the Y and Z coordinates of the input (the X coordinate doesn't matter to
+           secp256k1_gej_has_quad_y_var). Note that the resulting coordinates will
+           generally not correspond to a point on the curve, but this is not a problem
+           for the code being benchmarked here. Adding and normalizing have less
+           overhead than EC operations (which could guarantee the point remains on the
+           curve). */
+        secp256k1_fe_add(&data->gej[0].y, &data->fe[1]);
+        secp256k1_fe_add(&data->gej[0].z, &data->fe[2]);
+        secp256k1_fe_normalize_var(&data->gej[0].y);
+        secp256k1_fe_normalize_var(&data->gej[0].z);
+    }
+    CHECK(j <= iters);
+}
+
+void bench_group_to_affine_var(void* arg, int iters) {
+    int i;
+    bench_inv *data = (bench_inv*)arg;
+
+    for (i = 0; i < iters; ++i) {
+        secp256k1_ge_set_gej_var(&data->ge[1], &data->gej[0]);
+        /* Use the output affine X/Y coordinates to vary the input X/Y/Z coordinates.
+           Similar to bench_group_jacobi_var, this approach does not result in
+           coordinates of points on the curve. */
+        secp256k1_fe_add(&data->gej[0].x, &data->ge[1].y);
+        secp256k1_fe_add(&data->gej[0].y, &data->fe[2]);
+        secp256k1_fe_add(&data->gej[0].z, &data->ge[1].x);
+        secp256k1_fe_normalize_var(&data->gej[0].x);
+        secp256k1_fe_normalize_var(&data->gej[0].y);
+        secp256k1_fe_normalize_var(&data->gej[0].z);
     }
-    CHECK(j == iters);
 }
 
 void bench_ecmult_wnaf(void* arg, int iters) {
@@ -248,8 +300,8 @@ void bench_ecmult_wnaf(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        bits += secp256k1_ecmult_wnaf(data->wnaf, 256, &data->scalar_x, WINDOW_A);
-        overflow += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        bits += secp256k1_ecmult_wnaf(data->wnaf, 256, &data->scalar[0], WINDOW_A);
+        overflow += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(overflow >= 0);
     CHECK(bits <= 256*iters);
@@ -260,8 +312,8 @@ void bench_wnaf_const(void* arg, int iters) {
     bench_inv *data = (bench_inv*)arg;
 
     for (i = 0; i < iters; i++) {
-        bits += secp256k1_wnaf_const(data->wnaf, &data->scalar_x, WINDOW_A, 256);
-        overflow += secp256k1_scalar_add(&data->scalar_x, &data->scalar_x, &data->scalar_y);
+        bits += secp256k1_wnaf_const(data->wnaf, &data->scalar[0], WINDOW_A, 256);
+        overflow += secp256k1_scalar_add(&data->scalar[0], &data->scalar[0], &data->scalar[1]);
     }
     CHECK(overflow >= 0);
     CHECK(bits <= 256*iters);
@@ -323,14 +375,15 @@ void bench_context_sign(void* arg, int iters) {
 void bench_num_jacobi(void* arg, int iters) {
     int i, j = 0;
     bench_inv *data = (bench_inv*)arg;
-    secp256k1_num nx, norder;
+    secp256k1_num nx, na, norder;
 
-    secp256k1_scalar_get_num(&nx, &data->scalar_x);
+    secp256k1_scalar_get_num(&nx, &data->scalar[0]);
     secp256k1_scalar_order_get_num(&norder);
-    secp256k1_scalar_get_num(&norder, &data->scalar_y);
+    secp256k1_scalar_get_num(&na, &data->scalar[1]);
 
     for (i = 0; i < iters; i++) {
         j += secp256k1_num_jacobi(&nx, &norder);
+        secp256k1_num_add(&nx, &nx, &na);
     }
     CHECK(j <= iters);
 }
@@ -363,6 +416,7 @@ int main(int argc, char **argv) {
     if (have_flag(argc, argv, "group") || have_flag(argc, argv, "add")) run_benchmark("group_add_affine", bench_group_add_affine, bench_setup, NULL, &data, 10, iters*10);
     if (have_flag(argc, argv, "group") || have_flag(argc, argv, "add")) run_benchmark("group_add_affine_var", bench_group_add_affine_var, bench_setup, NULL, &data, 10, iters*10);
     if (have_flag(argc, argv, "group") || have_flag(argc, argv, "jacobi")) run_benchmark("group_jacobi_var", bench_group_jacobi_var, bench_setup, NULL, &data, 10, iters);
+    if (have_flag(argc, argv, "group") || have_flag(argc, argv, "to_affine")) run_benchmark("group_to_affine_var", bench_group_to_affine_var, bench_setup, NULL, &data, 10, iters);
 
     if (have_flag(argc, argv, "ecmult") || have_flag(argc, argv, "wnaf")) run_benchmark("wnaf_const", bench_wnaf_const, bench_setup, NULL, &data, 10, iters);
     if (have_flag(argc, argv, "ecmult") || have_flag(argc, argv, "wnaf")) run_benchmark("ecmult_wnaf", bench_ecmult_wnaf, bench_setup, NULL, &data, 10, iters);
diff --git a/src/secp256k1/src/bench_schnorrsig.c b/src/secp256k1/src/bench_schnorrsig.c
new file mode 100644
index 0000000000..315f5af28e
--- /dev/null
+++ b/src/secp256k1/src/bench_schnorrsig.c
@@ -0,0 +1,102 @@
+/**********************************************************************
+ * Copyright (c) 2018-2020 Andrew Poelstra, Jonas Nick                *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#include <string.h>
+#include <stdlib.h>
+
+
+#include "include/secp256k1.h"
+#include "include/secp256k1_schnorrsig.h"
+#include "util.h"
+#include "bench.h"
+
+typedef struct {
+    secp256k1_context *ctx;
+    int n;
+
+    const secp256k1_keypair **keypairs;
+    const unsigned char **pk;
+    const unsigned char **sigs;
+    const unsigned char **msgs;
+} bench_schnorrsig_data;
+
+void bench_schnorrsig_sign(void* arg, int iters) {
+    bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
+    int i;
+    unsigned char msg[32] = "benchmarkexamplemessagetemplate";
+    unsigned char sig[64];
+
+    for (i = 0; i < iters; i++) {
+        msg[0] = i;
+        msg[1] = i >> 8;
+        CHECK(secp256k1_schnorrsig_sign(data->ctx, sig, msg, data->keypairs[i], NULL, NULL));
+    }
+}
+
+void bench_schnorrsig_verify(void* arg, int iters) {
+    bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
+    int i;
+
+    for (i = 0; i < iters; i++) {
+        secp256k1_xonly_pubkey pk;
+        CHECK(secp256k1_xonly_pubkey_parse(data->ctx, &pk, data->pk[i]) == 1);
+        CHECK(secp256k1_schnorrsig_verify(data->ctx, data->sigs[i], data->msgs[i], &pk));
+    }
+}
+
+int main(void) {
+    int i;
+    bench_schnorrsig_data data;
+    int iters = get_iters(10000);
+
+    data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY | SECP256K1_CONTEXT_SIGN);
+    data.keypairs = (const secp256k1_keypair **)malloc(iters * sizeof(secp256k1_keypair *));
+    data.pk = (const unsigned char **)malloc(iters * sizeof(unsigned char *));
+    data.msgs = (const unsigned char **)malloc(iters * sizeof(unsigned char *));
+    data.sigs = (const unsigned char **)malloc(iters * sizeof(unsigned char *));
+
+    for (i = 0; i < iters; i++) {
+        unsigned char sk[32];
+        unsigned char *msg = (unsigned char *)malloc(32);
+        unsigned char *sig = (unsigned char *)malloc(64);
+        secp256k1_keypair *keypair = (secp256k1_keypair *)malloc(sizeof(*keypair));
+        unsigned char *pk_char = (unsigned char *)malloc(32);
+        secp256k1_xonly_pubkey pk;
+        msg[0] = sk[0] = i;
+        msg[1] = sk[1] = i >> 8;
+        msg[2] = sk[2] = i >> 16;
+        msg[3] = sk[3] = i >> 24;
+        memset(&msg[4], 'm', 28);
+        memset(&sk[4], 's', 28);
+
+        data.keypairs[i] = keypair;
+        data.pk[i] = pk_char;
+        data.msgs[i] = msg;
+        data.sigs[i] = sig;
+
+        CHECK(secp256k1_keypair_create(data.ctx, keypair, sk));
+        CHECK(secp256k1_schnorrsig_sign(data.ctx, sig, msg, keypair, NULL, NULL));
+        CHECK(secp256k1_keypair_xonly_pub(data.ctx, &pk, NULL, keypair));
+        CHECK(secp256k1_xonly_pubkey_serialize(data.ctx, pk_char, &pk) == 1);
+    }
+
+    run_benchmark("schnorrsig_sign", bench_schnorrsig_sign, NULL, NULL, (void *) &data, 10, iters);
+    run_benchmark("schnorrsig_verify", bench_schnorrsig_verify, NULL, NULL, (void *) &data, 10, iters);
+
+    for (i = 0; i < iters; i++) {
+        free((void *)data.keypairs[i]);
+        free((void *)data.pk[i]);
+        free((void *)data.msgs[i]);
+        free((void *)data.sigs[i]);
+    }
+    free(data.keypairs);
+    free(data.pk);
+    free(data.msgs);
+    free(data.sigs);
+
+    secp256k1_context_destroy(data.ctx);
+    return 0;
+}
diff --git a/src/secp256k1/src/ecmult_const_impl.h b/src/secp256k1/src/ecmult_const_impl.h
index 6d6d354aa4..55b61e4937 100644
--- a/src/secp256k1/src/ecmult_const_impl.h
+++ b/src/secp256k1/src/ecmult_const_impl.h
@@ -105,16 +105,22 @@ static int secp256k1_wnaf_const(int *wnaf, const secp256k1_scalar *scalar, int w
     /* 4 */
     u_last = secp256k1_scalar_shr_int(&s, w);
     do {
-        int sign;
         int even;
 
         /* 4.1 4.4 */
         u = secp256k1_scalar_shr_int(&s, w);
         /* 4.2 */
         even = ((u & 1) == 0);
-        sign = 2 * (u_last > 0) - 1;
-        u += sign * even;
-        u_last -= sign * even * (1 << w);
+        /* In contrast to the original algorithm, u_last is always > 0 and
+         * therefore we do not need to check its sign. In particular, it's easy
+         * to see that u_last is never < 0 because u is never < 0. Moreover,
+         * u_last is never = 0 because u is never even after a loop
+         * iteration. The same holds analogously for the initial value of
+         * u_last (in the first loop iteration). */
+        VERIFY_CHECK(u_last > 0);
+        VERIFY_CHECK((u_last & 1) == 1);
+        u += even;
+        u_last -= even * (1 << w);
 
         /* 4.3, adapted for global sign change */
         wnaf[word++] = u_last * global_sign;
@@ -202,7 +208,7 @@ static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, cons
         int n;
         int j;
         for (j = 0; j < WINDOW_A - 1; ++j) {
-            secp256k1_gej_double_nonzero(r, r);
+            secp256k1_gej_double(r, r);
         }
 
         n = wnaf_1[i];
diff --git a/src/secp256k1/src/field.h b/src/secp256k1/src/field.h
index 7993a1f11e..aca1fb72c5 100644
--- a/src/secp256k1/src/field.h
+++ b/src/secp256k1/src/field.h
@@ -22,16 +22,16 @@
 #include "libsecp256k1-config.h"
 #endif
 
-#if defined(USE_FIELD_10X26)
-#include "field_10x26.h"
-#elif defined(USE_FIELD_5X52)
+#include "util.h"
+
+#if defined(SECP256K1_WIDEMUL_INT128)
 #include "field_5x52.h"
+#elif defined(SECP256K1_WIDEMUL_INT64)
+#include "field_10x26.h"
 #else
-#error "Please select field implementation"
+#error "Please select wide multiplication implementation"
 #endif
 
-#include "util.h"
-
 /** Normalize a field element. This brings the field element to a canonical representation, reduces
  *  its magnitude to 1, and reduces it modulo field size `p`.
  */
diff --git a/src/secp256k1/src/field_5x52.h b/src/secp256k1/src/field_5x52.h
index fc5bfe357e..6a068484c2 100644
--- a/src/secp256k1/src/field_5x52.h
+++ b/src/secp256k1/src/field_5x52.h
@@ -46,4 +46,10 @@ typedef struct {
     (d6) | (((uint64_t)(d7)) << 32) \
 }}
 
+#define SECP256K1_FE_STORAGE_CONST_GET(d) \
+    (uint32_t)(d.n[3] >> 32), (uint32_t)d.n[3], \
+    (uint32_t)(d.n[2] >> 32), (uint32_t)d.n[2], \
+    (uint32_t)(d.n[1] >> 32), (uint32_t)d.n[1], \
+    (uint32_t)(d.n[0] >> 32), (uint32_t)d.n[0]
+
 #endif /* SECP256K1_FIELD_REPR_H */
diff --git a/src/secp256k1/src/field_impl.h b/src/secp256k1/src/field_impl.h
index 485921a60e..18e4d2f30e 100644
--- a/src/secp256k1/src/field_impl.h
+++ b/src/secp256k1/src/field_impl.h
@@ -14,12 +14,12 @@
 #include "util.h"
 #include "num.h"
 
-#if defined(USE_FIELD_10X26)
-#include "field_10x26_impl.h"
-#elif defined(USE_FIELD_5X52)
+#if defined(SECP256K1_WIDEMUL_INT128)
 #include "field_5x52_impl.h"
+#elif defined(SECP256K1_WIDEMUL_INT64)
+#include "field_10x26_impl.h"
 #else
-#error "Please select field implementation"
+#error "Please select wide multiplication implementation"
 #endif
 
 SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b) {
diff --git a/src/secp256k1/src/gen_context.c b/src/secp256k1/src/gen_context.c
index 539f574bfd..8b7729aee4 100644
--- a/src/secp256k1/src/gen_context.c
+++ b/src/secp256k1/src/gen_context.c
@@ -13,6 +13,7 @@
 #include "basic-config.h"
 
 #include "include/secp256k1.h"
+#include "assumptions.h"
 #include "util.h"
 #include "field_impl.h"
 #include "scalar_impl.h"
diff --git a/src/secp256k1/src/group.h b/src/secp256k1/src/group.h
index 863644f0f0..6185be052d 100644
--- a/src/secp256k1/src/group.h
+++ b/src/secp256k1/src/group.h
@@ -95,8 +95,8 @@ static int secp256k1_gej_is_infinity(const secp256k1_gej *a);
 /** Check whether a group element's y coordinate is a quadratic residue. */
 static int secp256k1_gej_has_quad_y_var(const secp256k1_gej *a);
 
-/** Set r equal to the double of a, a cannot be infinity. Constant time. */
-static void secp256k1_gej_double_nonzero(secp256k1_gej *r, const secp256k1_gej *a);
+/** Set r equal to the double of a. Constant time. */
+static void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a);
 
 /** Set r equal to the double of a. If rzr is not-NULL this sets *rzr such that r->z == a->z * *rzr (where infinity means an implicit z = 0). */
 static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe *rzr);
diff --git a/src/secp256k1/src/group_impl.h b/src/secp256k1/src/group_impl.h
index 43b039becf..ccd93d3483 100644
--- a/src/secp256k1/src/group_impl.h
+++ b/src/secp256k1/src/group_impl.h
@@ -303,7 +303,7 @@ static int secp256k1_ge_is_valid_var(const secp256k1_ge *a) {
     return secp256k1_fe_equal_var(&y2, &x3);
 }
 
-static SECP256K1_INLINE void secp256k1_gej_double_nonzero(secp256k1_gej *r, const secp256k1_gej *a) {
+static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a) {
     /* Operations: 3 mul, 4 sqr, 0 normalize, 12 mul_int/add/negate.
      *
      * Note that there is an implementation described at
@@ -313,8 +313,7 @@ static SECP256K1_INLINE void secp256k1_gej_double_nonzero(secp256k1_gej *r, cons
      */
     secp256k1_fe t1,t2,t3,t4;
 
-    VERIFY_CHECK(!secp256k1_gej_is_infinity(a));
-    r->infinity = 0;
+    r->infinity = a->infinity;
 
     secp256k1_fe_mul(&r->z, &a->z, &a->y);
     secp256k1_fe_mul_int(&r->z, 2);       /* Z' = 2*Y*Z (2) */
@@ -363,7 +362,7 @@ static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, s
         secp256k1_fe_mul_int(rzr, 2);
     }
 
-    secp256k1_gej_double_nonzero(r, a);
+    secp256k1_gej_double(r, a);
 }
 
 static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_gej *b, secp256k1_fe *rzr) {
@@ -400,7 +399,7 @@ static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, cons
             if (rzr != NULL) {
                 secp256k1_fe_set_int(rzr, 0);
             }
-            r->infinity = 1;
+            secp256k1_gej_set_infinity(r);
         }
         return;
     }
@@ -450,7 +449,7 @@ static void secp256k1_gej_add_ge_var(secp256k1_gej *r, const secp256k1_gej *a, c
             if (rzr != NULL) {
                 secp256k1_fe_set_int(rzr, 0);
             }
-            r->infinity = 1;
+            secp256k1_gej_set_infinity(r);
         }
         return;
     }
@@ -509,7 +508,7 @@ static void secp256k1_gej_add_zinv_var(secp256k1_gej *r, const secp256k1_gej *a,
         if (secp256k1_fe_normalizes_to_zero_var(&i)) {
             secp256k1_gej_double_var(r, a, NULL);
         } else {
-            r->infinity = 1;
+            secp256k1_gej_set_infinity(r);
         }
         return;
     }
diff --git a/src/secp256k1/src/hash_impl.h b/src/secp256k1/src/hash_impl.h
index 782f97216c..409772587b 100644
--- a/src/secp256k1/src/hash_impl.h
+++ b/src/secp256k1/src/hash_impl.h
@@ -8,6 +8,7 @@
 #define SECP256K1_HASH_IMPL_H
 
 #include "hash.h"
+#include "util.h"
 
 #include <stdlib.h>
 #include <stdint.h>
@@ -27,9 +28,9 @@
     (h) = t1 + t2; \
 } while(0)
 
-#ifdef WORDS_BIGENDIAN
+#if defined(SECP256K1_BIG_ENDIAN)
 #define BE32(x) (x)
-#else
+#elif defined(SECP256K1_LITTLE_ENDIAN)
 #define BE32(p) ((((p) & 0xFF) << 24) | (((p) & 0xFF00) << 8) | (((p) & 0xFF0000) >> 8) | (((p) & 0xFF000000) >> 24))
 #endif
 
@@ -163,6 +164,19 @@ static void secp256k1_sha256_finalize(secp256k1_sha256 *hash, unsigned char *out
     memcpy(out32, (const unsigned char*)out, 32);
 }
 
+/* Initializes a sha256 struct and writes the 64 byte string
+ * SHA256(tag)||SHA256(tag) into it. */
+static void secp256k1_sha256_initialize_tagged(secp256k1_sha256 *hash, const unsigned char *tag, size_t taglen) {
+    unsigned char buf[32];
+    secp256k1_sha256_initialize(hash);
+    secp256k1_sha256_write(hash, tag, taglen);
+    secp256k1_sha256_finalize(hash, buf);
+
+    secp256k1_sha256_initialize(hash);
+    secp256k1_sha256_write(hash, buf, 32);
+    secp256k1_sha256_write(hash, buf, 32);
+}
+
 static void secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256 *hash, const unsigned char *key, size_t keylen) {
     size_t n;
     unsigned char rkey[64];
diff --git a/src/secp256k1/src/modules/extrakeys/Makefile.am.include b/src/secp256k1/src/modules/extrakeys/Makefile.am.include
new file mode 100644
index 0000000000..8515f92e7a
--- /dev/null
+++ b/src/secp256k1/src/modules/extrakeys/Makefile.am.include
@@ -0,0 +1,3 @@
+include_HEADERS += include/secp256k1_extrakeys.h
+noinst_HEADERS += src/modules/extrakeys/tests_impl.h
+noinst_HEADERS += src/modules/extrakeys/main_impl.h
diff --git a/src/secp256k1/src/modules/extrakeys/main_impl.h b/src/secp256k1/src/modules/extrakeys/main_impl.h
new file mode 100644
index 0000000000..d319215355
--- /dev/null
+++ b/src/secp256k1/src/modules/extrakeys/main_impl.h
@@ -0,0 +1,248 @@
+/**********************************************************************
+ * Copyright (c) 2020 Jonas Nick                                      *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_EXTRAKEYS_MAIN_
+#define _SECP256K1_MODULE_EXTRAKEYS_MAIN_
+
+#include "include/secp256k1.h"
+#include "include/secp256k1_extrakeys.h"
+
+static SECP256K1_INLINE int secp256k1_xonly_pubkey_load(const secp256k1_context* ctx, secp256k1_ge *ge, const secp256k1_xonly_pubkey *pubkey) {
+    return secp256k1_pubkey_load(ctx, ge, (const secp256k1_pubkey *) pubkey);
+}
+
+static SECP256K1_INLINE void secp256k1_xonly_pubkey_save(secp256k1_xonly_pubkey *pubkey, secp256k1_ge *ge) {
+    secp256k1_pubkey_save((secp256k1_pubkey *) pubkey, ge);
+}
+
+int secp256k1_xonly_pubkey_parse(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, const unsigned char *input32) {
+    secp256k1_ge pk;
+    secp256k1_fe x;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    memset(pubkey, 0, sizeof(*pubkey));
+    ARG_CHECK(input32 != NULL);
+
+    if (!secp256k1_fe_set_b32(&x, input32)) {
+        return 0;
+    }
+    if (!secp256k1_ge_set_xo_var(&pk, &x, 0)) {
+        return 0;
+    }
+    secp256k1_xonly_pubkey_save(pubkey, &pk);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_serialize(const secp256k1_context* ctx, unsigned char *output32, const secp256k1_xonly_pubkey *pubkey) {
+    secp256k1_ge pk;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(output32 != NULL);
+    memset(output32, 0, 32);
+    ARG_CHECK(pubkey != NULL);
+
+    if (!secp256k1_xonly_pubkey_load(ctx, &pk, pubkey)) {
+        return 0;
+    }
+    secp256k1_fe_get_b32(output32, &pk.x);
+    return 1;
+}
+
+/** Keeps a group element as is if it has an even Y and otherwise negates it.
+ *  y_parity is set to 0 in the former case and to 1 in the latter case.
+ *  Requires that the coordinates of r are normalized. */
+static int secp256k1_extrakeys_ge_even_y(secp256k1_ge *r) {
+    int y_parity = 0;
+    VERIFY_CHECK(!secp256k1_ge_is_infinity(r));
+
+    if (secp256k1_fe_is_odd(&r->y)) {
+        secp256k1_fe_negate(&r->y, &r->y, 1);
+        y_parity = 1;
+    }
+    return y_parity;
+}
+
+int secp256k1_xonly_pubkey_from_pubkey(const secp256k1_context* ctx, secp256k1_xonly_pubkey *xonly_pubkey, int *pk_parity, const secp256k1_pubkey *pubkey) {
+    secp256k1_ge pk;
+    int tmp;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(xonly_pubkey != NULL);
+    ARG_CHECK(pubkey != NULL);
+
+    if (!secp256k1_pubkey_load(ctx, &pk, pubkey)) {
+        return 0;
+    }
+    tmp = secp256k1_extrakeys_ge_even_y(&pk);
+    if (pk_parity != NULL) {
+        *pk_parity = tmp;
+    }
+    secp256k1_xonly_pubkey_save(xonly_pubkey, &pk);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey *output_pubkey, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
+    secp256k1_ge pk;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(output_pubkey != NULL);
+    memset(output_pubkey, 0, sizeof(*output_pubkey));
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(internal_pubkey != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
+        || !secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32)) {
+        return 0;
+    }
+    secp256k1_pubkey_save(output_pubkey, &pk);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_tweak_add_check(const secp256k1_context* ctx, const unsigned char *tweaked_pubkey32, int tweaked_pk_parity, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
+    secp256k1_ge pk;
+    unsigned char pk_expected32[32];
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(internal_pubkey != NULL);
+    ARG_CHECK(tweaked_pubkey32 != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    if (!secp256k1_xonly_pubkey_load(ctx, &pk, internal_pubkey)
+        || !secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32)) {
+        return 0;
+    }
+    secp256k1_fe_normalize_var(&pk.x);
+    secp256k1_fe_normalize_var(&pk.y);
+    secp256k1_fe_get_b32(pk_expected32, &pk.x);
+
+    return memcmp(&pk_expected32, tweaked_pubkey32, 32) == 0
+            && secp256k1_fe_is_odd(&pk.y) == tweaked_pk_parity;
+}
+
+static void secp256k1_keypair_save(secp256k1_keypair *keypair, const secp256k1_scalar *sk, secp256k1_ge *pk) {
+    secp256k1_scalar_get_b32(&keypair->data[0], sk);
+    secp256k1_pubkey_save((secp256k1_pubkey *)&keypair->data[32], pk);
+}
+
+
+static int secp256k1_keypair_seckey_load(const secp256k1_context* ctx, secp256k1_scalar *sk, const secp256k1_keypair *keypair) {
+    int ret;
+
+    ret = secp256k1_scalar_set_b32_seckey(sk, &keypair->data[0]);
+    /* We can declassify ret here because sk is only zero if a keypair function
+     * failed (which zeroes the keypair) and its return value is ignored. */
+    secp256k1_declassify(ctx, &ret, sizeof(ret));
+    ARG_CHECK(ret);
+    return ret;
+}
+
+/* Load a keypair into pk and sk (if non-NULL). This function declassifies pk
+ * and ARG_CHECKs that the keypair is not invalid. It always initializes sk and
+ * pk with dummy values. */
+static int secp256k1_keypair_load(const secp256k1_context* ctx, secp256k1_scalar *sk, secp256k1_ge *pk, const secp256k1_keypair *keypair) {
+    int ret;
+    const secp256k1_pubkey *pubkey = (const secp256k1_pubkey *)&keypair->data[32];
+
+    /* Need to declassify the pubkey because pubkey_load ARG_CHECKs if it's
+     * invalid. */
+    secp256k1_declassify(ctx, pubkey, sizeof(*pubkey));
+    ret = secp256k1_pubkey_load(ctx, pk, pubkey);
+    if (sk != NULL) {
+        ret = ret && secp256k1_keypair_seckey_load(ctx, sk, keypair);
+    }
+    if (!ret) {
+        *pk = secp256k1_ge_const_g;
+        if (sk != NULL) {
+            *sk = secp256k1_scalar_one;
+        }
+    }
+    return ret;
+}
+
+int secp256k1_keypair_create(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *seckey32) {
+    secp256k1_scalar sk;
+    secp256k1_ge pk;
+    int ret = 0;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(keypair != NULL);
+    memset(keypair, 0, sizeof(*keypair));
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(seckey32 != NULL);
+
+    ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &sk, &pk, seckey32);
+    secp256k1_keypair_save(keypair, &sk, &pk);
+    memczero(keypair, sizeof(*keypair), !ret);
+
+    secp256k1_scalar_clear(&sk);
+    return ret;
+}
+
+int secp256k1_keypair_pub(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const secp256k1_keypair *keypair) {
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    memset(pubkey, 0, sizeof(*pubkey));
+    ARG_CHECK(keypair != NULL);
+
+    memcpy(pubkey->data, &keypair->data[32], sizeof(*pubkey));
+    return 1;
+}
+
+int secp256k1_keypair_xonly_pub(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, int *pk_parity, const secp256k1_keypair *keypair) {
+    secp256k1_ge pk;
+    int tmp;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    memset(pubkey, 0, sizeof(*pubkey));
+    ARG_CHECK(keypair != NULL);
+
+    if (!secp256k1_keypair_load(ctx, NULL, &pk, keypair)) {
+        return 0;
+    }
+    tmp = secp256k1_extrakeys_ge_even_y(&pk);
+    if (pk_parity != NULL) {
+        *pk_parity = tmp;
+    }
+    secp256k1_xonly_pubkey_save(pubkey, &pk);
+
+    return 1;
+}
+
+int secp256k1_keypair_xonly_tweak_add(const secp256k1_context* ctx, secp256k1_keypair *keypair, const unsigned char *tweak32) {
+    secp256k1_ge pk;
+    secp256k1_scalar sk;
+    int y_parity;
+    int ret;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(keypair != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    ret = secp256k1_keypair_load(ctx, &sk, &pk, keypair);
+    memset(keypair, 0, sizeof(*keypair));
+
+    y_parity = secp256k1_extrakeys_ge_even_y(&pk);
+    if (y_parity == 1) {
+        secp256k1_scalar_negate(&sk, &sk);
+    }
+
+    ret &= secp256k1_ec_seckey_tweak_add_helper(&sk, tweak32);
+    ret &= secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &pk, tweak32);
+
+    secp256k1_declassify(ctx, &ret, sizeof(ret));
+    if (ret) {
+        secp256k1_keypair_save(keypair, &sk, &pk);
+    }
+
+    secp256k1_scalar_clear(&sk);
+    return ret;
+}
+
+#endif
diff --git a/src/secp256k1/src/modules/extrakeys/tests_impl.h b/src/secp256k1/src/modules/extrakeys/tests_impl.h
new file mode 100644
index 0000000000..fc9d40eda1
--- /dev/null
+++ b/src/secp256k1/src/modules/extrakeys/tests_impl.h
@@ -0,0 +1,524 @@
+/**********************************************************************
+ * Copyright (c) 2020 Jonas Nick                                      *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_EXTRAKEYS_TESTS_
+#define _SECP256K1_MODULE_EXTRAKEYS_TESTS_
+
+#include "secp256k1_extrakeys.h"
+
+static secp256k1_context* api_test_context(int flags, int *ecount) {
+    secp256k1_context *ctx0 = secp256k1_context_create(flags);
+    secp256k1_context_set_error_callback(ctx0, counting_illegal_callback_fn, ecount);
+    secp256k1_context_set_illegal_callback(ctx0, counting_illegal_callback_fn, ecount);
+    return ctx0;
+}
+
+void test_xonly_pubkey(void) {
+    secp256k1_pubkey pk;
+    secp256k1_xonly_pubkey xonly_pk, xonly_pk_tmp;
+    secp256k1_ge pk1;
+    secp256k1_ge pk2;
+    secp256k1_fe y;
+    unsigned char sk[32];
+    unsigned char xy_sk[32];
+    unsigned char buf32[32];
+    unsigned char ones32[32];
+    unsigned char zeros64[64] = { 0 };
+    int pk_parity;
+    int i;
+
+    int ecount;
+    secp256k1_context *none = api_test_context(SECP256K1_CONTEXT_NONE, &ecount);
+    secp256k1_context *sign = api_test_context(SECP256K1_CONTEXT_SIGN, &ecount);
+    secp256k1_context *verify = api_test_context(SECP256K1_CONTEXT_VERIFY, &ecount);
+
+    secp256k1_rand256(sk);
+    memset(ones32, 0xFF, 32);
+    secp256k1_rand256(xy_sk);
+    CHECK(secp256k1_ec_pubkey_create(sign, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, &pk_parity, &pk) == 1);
+
+    /* Test xonly_pubkey_from_pubkey */
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(sign, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(verify, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, NULL, &pk_parity, &pk) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, NULL, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, &pk_parity, NULL) == 0);
+    CHECK(ecount == 2);
+    memset(&pk, 0, sizeof(pk));
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, &pk_parity, &pk) == 0);
+    CHECK(ecount == 3);
+
+    /* Choose a secret key such that the resulting pubkey and xonly_pubkey match. */
+    memset(sk, 0, sizeof(sk));
+    sk[0] = 1;
+    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(memcmp(&pk, &xonly_pk, sizeof(pk)) == 0);
+    CHECK(pk_parity == 0);
+
+    /* Choose a secret key such that pubkey and xonly_pubkey are each others
+     * negation. */
+    sk[0] = 2;
+    CHECK(secp256k1_ec_pubkey_create(ctx, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(memcmp(&xonly_pk, &pk, sizeof(xonly_pk)) != 0);
+    CHECK(pk_parity == 1);
+    secp256k1_pubkey_load(ctx, &pk1, &pk);
+    secp256k1_pubkey_load(ctx, &pk2, (secp256k1_pubkey *) &xonly_pk);
+    CHECK(secp256k1_fe_equal(&pk1.x, &pk2.x) == 1);
+    secp256k1_fe_negate(&y, &pk2.y, 1);
+    CHECK(secp256k1_fe_equal(&pk1.y, &y) == 1);
+
+    /* Test xonly_pubkey_serialize and xonly_pubkey_parse */
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_serialize(none, NULL, &xonly_pk) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(none, buf32, NULL) == 0);
+    CHECK(memcmp(buf32, zeros64, 32) == 0);
+    CHECK(ecount == 2);
+    {
+        /* A pubkey filled with 0s will fail to serialize due to pubkey_load
+         * special casing. */
+        secp256k1_xonly_pubkey pk_tmp;
+        memset(&pk_tmp, 0, sizeof(pk_tmp));
+        CHECK(secp256k1_xonly_pubkey_serialize(none, buf32, &pk_tmp) == 0);
+    }
+    /* pubkey_load called illegal callback */
+    CHECK(ecount == 3);
+
+    CHECK(secp256k1_xonly_pubkey_serialize(none, buf32, &xonly_pk) == 1);
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_parse(none, NULL, buf32) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(none, &xonly_pk, NULL) == 0);
+    CHECK(ecount == 2);
+
+    /* Serialization and parse roundtrip */
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, NULL, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk_tmp, buf32) == 1);
+    CHECK(memcmp(&xonly_pk, &xonly_pk_tmp, sizeof(xonly_pk)) == 0);
+
+    /* Test parsing invalid field elements */
+    memset(&xonly_pk, 1, sizeof(xonly_pk));
+    /* Overflowing field element */
+    CHECK(secp256k1_xonly_pubkey_parse(none, &xonly_pk, ones32) == 0);
+    CHECK(memcmp(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
+    memset(&xonly_pk, 1, sizeof(xonly_pk));
+    /* There's no point with x-coordinate 0 on secp256k1 */
+    CHECK(secp256k1_xonly_pubkey_parse(none, &xonly_pk, zeros64) == 0);
+    CHECK(memcmp(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
+    /* If a random 32-byte string can not be parsed with ec_pubkey_parse
+     * (because interpreted as X coordinate it does not correspond to a point on
+     * the curve) then xonly_pubkey_parse should fail as well. */
+    for (i = 0; i < count; i++) {
+        unsigned char rand33[33];
+        secp256k1_rand256(&rand33[1]);
+        rand33[0] = SECP256K1_TAG_PUBKEY_EVEN;
+        if (!secp256k1_ec_pubkey_parse(ctx, &pk, rand33, 33)) {
+            memset(&xonly_pk, 1, sizeof(xonly_pk));
+            CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, &rand33[1]) == 0);
+            CHECK(memcmp(&xonly_pk, zeros64, sizeof(xonly_pk)) == 0);
+        } else {
+            CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk, &rand33[1]) == 1);
+        }
+    }
+    CHECK(ecount == 2);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(verify);
+}
+
+void test_xonly_pubkey_tweak(void) {
+    unsigned char zeros64[64] = { 0 };
+    unsigned char overflows[32];
+    unsigned char sk[32];
+    secp256k1_pubkey internal_pk;
+    secp256k1_xonly_pubkey internal_xonly_pk;
+    secp256k1_pubkey output_pk;
+    int pk_parity;
+    unsigned char tweak[32];
+    int i;
+
+    int ecount;
+    secp256k1_context *none = api_test_context(SECP256K1_CONTEXT_NONE, &ecount);
+    secp256k1_context *sign = api_test_context(SECP256K1_CONTEXT_SIGN, &ecount);
+    secp256k1_context *verify = api_test_context(SECP256K1_CONTEXT_VERIFY, &ecount);
+
+    memset(overflows, 0xff, sizeof(overflows));
+    secp256k1_rand256(tweak);
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_ec_pubkey_create(ctx, &internal_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_tweak_add(none, &output_pk, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(sign, &output_pk, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, NULL, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, NULL, tweak) == 0);
+    CHECK(ecount == 4);
+    /* NULL internal_xonly_pk zeroes the output_pk */
+    CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk)) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, NULL) == 0);
+    CHECK(ecount == 5);
+    /* NULL tweak zeroes the output_pk */
+    CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk)) == 0);
+
+    /* Invalid tweak zeroes the output_pk */
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, overflows) == 0);
+    CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk))  == 0);
+
+    /* A zero tweak is fine */
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, zeros64) == 1);
+
+    /* Fails if the resulting key was infinity */
+    for (i = 0; i < count; i++) {
+        secp256k1_scalar scalar_tweak;
+        /* Because sk may be negated before adding, we need to try with tweak =
+         * sk as well as tweak = -sk. */
+        secp256k1_scalar_set_b32(&scalar_tweak, sk, NULL);
+        secp256k1_scalar_negate(&scalar_tweak, &scalar_tweak);
+        secp256k1_scalar_get_b32(tweak, &scalar_tweak);
+        CHECK((secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, sk) == 0)
+              || (secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, tweak) == 0));
+        CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk)) == 0);
+    }
+
+    /* Invalid pk with a valid tweak */
+    memset(&internal_xonly_pk, 0, sizeof(internal_xonly_pk));
+    secp256k1_rand256(tweak);
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk))  == 0);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(verify);
+}
+
+void test_xonly_pubkey_tweak_check(void) {
+    unsigned char zeros64[64] = { 0 };
+    unsigned char overflows[32];
+    unsigned char sk[32];
+    secp256k1_pubkey internal_pk;
+    secp256k1_xonly_pubkey internal_xonly_pk;
+    secp256k1_pubkey output_pk;
+    secp256k1_xonly_pubkey output_xonly_pk;
+    unsigned char output_pk32[32];
+    unsigned char buf32[32];
+    int pk_parity;
+    unsigned char tweak[32];
+
+    int ecount;
+    secp256k1_context *none = api_test_context(SECP256K1_CONTEXT_NONE, &ecount);
+    secp256k1_context *sign = api_test_context(SECP256K1_CONTEXT_SIGN, &ecount);
+    secp256k1_context *verify = api_test_context(SECP256K1_CONTEXT_VERIFY, &ecount);
+
+    memset(overflows, 0xff, sizeof(overflows));
+    secp256k1_rand256(tweak);
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_ec_pubkey_create(ctx, &internal_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &internal_xonly_pk, &pk_parity, &internal_pk) == 1);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_tweak_add(verify, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(verify, &output_xonly_pk, &pk_parity, &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &output_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(none, buf32, pk_parity, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(sign, buf32, pk_parity, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(verify, buf32, pk_parity, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(verify, NULL, pk_parity, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 3);
+    /* invalid pk_parity value */
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(verify, buf32, 2, &internal_xonly_pk, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(verify, buf32, pk_parity, NULL, tweak) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(verify, buf32, pk_parity, &internal_xonly_pk, NULL) == 0);
+    CHECK(ecount == 5);
+
+    memset(tweak, 1, sizeof(tweak));
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &internal_xonly_pk, NULL, &internal_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &output_xonly_pk, &pk_parity, &output_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, output_pk32, &output_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, pk_parity, &internal_xonly_pk, tweak) == 1);
+
+    /* Wrong pk_parity */
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, !pk_parity, &internal_xonly_pk, tweak) == 0);
+    /* Wrong public key */
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &internal_xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, buf32, pk_parity, &internal_xonly_pk, tweak) == 0);
+
+    /* Overflowing tweak not allowed */
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk32, pk_parity, &internal_xonly_pk, overflows) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &internal_xonly_pk, overflows) == 0);
+    CHECK(memcmp(&output_pk, zeros64, sizeof(output_pk)) == 0);
+    CHECK(ecount == 5);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(verify);
+}
+
+/* Starts with an initial pubkey and recursively creates N_PUBKEYS - 1
+ * additional pubkeys by calling tweak_add. Then verifies every tweak starting
+ * from the last pubkey. */
+#define N_PUBKEYS 32
+void test_xonly_pubkey_tweak_recursive(void) {
+    unsigned char sk[32];
+    secp256k1_pubkey pk[N_PUBKEYS];
+    unsigned char pk_serialized[32];
+    unsigned char tweak[N_PUBKEYS - 1][32];
+    int i;
+
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_ec_pubkey_create(ctx, &pk[0], sk) == 1);
+    /* Add tweaks */
+    for (i = 0; i < N_PUBKEYS - 1; i++) {
+        secp256k1_xonly_pubkey xonly_pk;
+        memset(tweak[i], i + 1, sizeof(tweak[i]));
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk[i]) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &pk[i + 1], &xonly_pk, tweak[i]) == 1);
+    }
+
+    /* Verify tweaks */
+    for (i = N_PUBKEYS - 1; i > 0; i--) {
+        secp256k1_xonly_pubkey xonly_pk;
+        int pk_parity;
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, &pk_parity, &pk[i]) == 1);
+        CHECK(secp256k1_xonly_pubkey_serialize(ctx, pk_serialized, &xonly_pk) == 1);
+        CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk, NULL, &pk[i - 1]) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, pk_serialized, pk_parity, &xonly_pk, tweak[i - 1]) == 1);
+    }
+}
+#undef N_PUBKEYS
+
+void test_keypair(void) {
+    unsigned char sk[32];
+    unsigned char zeros96[96] = { 0 };
+    unsigned char overflows[32];
+    secp256k1_keypair keypair;
+    secp256k1_pubkey pk, pk_tmp;
+    secp256k1_xonly_pubkey xonly_pk, xonly_pk_tmp;
+    int pk_parity, pk_parity_tmp;
+    int ecount;
+    secp256k1_context *none = api_test_context(SECP256K1_CONTEXT_NONE, &ecount);
+    secp256k1_context *sign = api_test_context(SECP256K1_CONTEXT_SIGN, &ecount);
+    secp256k1_context *verify = api_test_context(SECP256K1_CONTEXT_VERIFY, &ecount);
+
+    CHECK(sizeof(zeros96) == sizeof(keypair));
+    memset(overflows, 0xFF, sizeof(overflows));
+
+    /* Test keypair_create */
+    ecount = 0;
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(none, &keypair, sk) == 0);
+    CHECK(memcmp(zeros96, &keypair, sizeof(keypair)) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_keypair_create(verify, &keypair, sk) == 0);
+    CHECK(memcmp(zeros96, &keypair, sizeof(keypair)) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_create(sign, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_create(sign, NULL, sk) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_keypair_create(sign, &keypair, NULL) == 0);
+    CHECK(memcmp(zeros96, &keypair, sizeof(keypair)) == 0);
+    CHECK(ecount == 4);
+
+    /* Invalid secret key */
+    CHECK(secp256k1_keypair_create(sign, &keypair, zeros96) == 0);
+    CHECK(memcmp(zeros96, &keypair, sizeof(keypair)) == 0);
+    CHECK(secp256k1_keypair_create(sign, &keypair, overflows) == 0);
+    CHECK(memcmp(zeros96, &keypair, sizeof(keypair)) == 0);
+
+    /* Test keypair_pub */
+    ecount = 0;
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_pub(none, &pk, &keypair) == 1);
+    CHECK(secp256k1_keypair_pub(none, NULL, &keypair) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_keypair_pub(none, &pk, NULL) == 0);
+    CHECK(ecount == 2);
+    CHECK(memcmp(zeros96, &pk, sizeof(pk)) == 0);
+
+    /* Using an invalid keypair is fine for keypair_pub */
+    memset(&keypair, 0, sizeof(keypair));
+    CHECK(secp256k1_keypair_pub(none, &pk, &keypair) == 1);
+    CHECK(memcmp(zeros96, &pk, sizeof(pk)) == 0);
+
+    /* keypair holds the same pubkey as pubkey_create */
+    CHECK(secp256k1_ec_pubkey_create(sign, &pk, sk) == 1);
+    CHECK(secp256k1_keypair_create(sign, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_pub(none, &pk_tmp, &keypair) == 1);
+    CHECK(memcmp(&pk, &pk_tmp, sizeof(pk)) == 0);
+
+    /** Test keypair_xonly_pub **/
+    ecount = 0;
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk, &pk_parity, &keypair) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(none, NULL, &pk_parity, &keypair) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk, NULL, &keypair) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk, &pk_parity, NULL) == 0);
+    CHECK(ecount == 2);
+    CHECK(memcmp(zeros96, &xonly_pk, sizeof(xonly_pk)) == 0);
+    /* Using an invalid keypair will set the xonly_pk to 0 (first reset
+     * xonly_pk). */
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk, &pk_parity, &keypair) == 1);
+    memset(&keypair, 0, sizeof(keypair));
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk, &pk_parity, &keypair) == 0);
+    CHECK(memcmp(zeros96, &xonly_pk, sizeof(xonly_pk)) == 0);
+    CHECK(ecount == 3);
+
+    /** keypair holds the same xonly pubkey as pubkey_create **/
+    CHECK(secp256k1_ec_pubkey_create(sign, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &xonly_pk, &pk_parity, &pk) == 1);
+    CHECK(secp256k1_keypair_create(sign, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(none, &xonly_pk_tmp, &pk_parity_tmp, &keypair) == 1);
+    CHECK(memcmp(&xonly_pk, &xonly_pk_tmp, sizeof(pk)) == 0);
+    CHECK(pk_parity == pk_parity_tmp);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(verify);
+}
+
+void test_keypair_add(void) {
+    unsigned char sk[32];
+    secp256k1_keypair keypair;
+    unsigned char overflows[32];
+    unsigned char zeros96[96] = { 0 };
+    unsigned char tweak[32];
+    int i;
+    int ecount = 0;
+    secp256k1_context *none = api_test_context(SECP256K1_CONTEXT_NONE, &ecount);
+    secp256k1_context *sign = api_test_context(SECP256K1_CONTEXT_SIGN, &ecount);
+    secp256k1_context *verify = api_test_context(SECP256K1_CONTEXT_VERIFY, &ecount);
+
+    CHECK(sizeof(zeros96) == sizeof(keypair));
+    secp256k1_rand256(sk);
+    secp256k1_rand256(tweak);
+    memset(overflows, 0xFF, 32);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+
+    CHECK(secp256k1_keypair_xonly_tweak_add(none, &keypair, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(sign, &keypair, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, &keypair, tweak) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, NULL, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, &keypair, NULL) == 0);
+    CHECK(ecount == 4);
+    /* This does not set the keypair to zeroes */
+    CHECK(memcmp(&keypair, zeros96, sizeof(keypair)) != 0);
+
+    /* Invalid tweak zeroes the keypair */
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, overflows) == 0);
+    CHECK(memcmp(&keypair, zeros96, sizeof(keypair))  == 0);
+
+    /* A zero tweak is fine */
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, zeros96) == 1);
+
+    /* Fails if the resulting keypair was (sk=0, pk=infinity) */
+    for (i = 0; i < count; i++) {
+        secp256k1_scalar scalar_tweak;
+        secp256k1_keypair keypair_tmp;
+        secp256k1_rand256(sk);
+        CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+        memcpy(&keypair_tmp, &keypair, sizeof(keypair));
+        /* Because sk may be negated before adding, we need to try with tweak =
+         * sk as well as tweak = -sk. */
+        secp256k1_scalar_set_b32(&scalar_tweak, sk, NULL);
+        secp256k1_scalar_negate(&scalar_tweak, &scalar_tweak);
+        secp256k1_scalar_get_b32(tweak, &scalar_tweak);
+        CHECK((secp256k1_keypair_xonly_tweak_add(ctx, &keypair, sk) == 0)
+              || (secp256k1_keypair_xonly_tweak_add(ctx, &keypair_tmp, tweak) == 0));
+        CHECK(memcmp(&keypair, zeros96, sizeof(keypair)) == 0
+              || memcmp(&keypair_tmp, zeros96, sizeof(keypair_tmp)) == 0);
+    }
+
+    /* Invalid keypair with a valid tweak */
+    memset(&keypair, 0, sizeof(keypair));
+    secp256k1_rand256(tweak);
+    ecount = 0;
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, &keypair, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(memcmp(&keypair, zeros96, sizeof(keypair))  == 0);
+    /* Only seckey part of keypair invalid */
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    memset(&keypair, 0, 32);
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, &keypair, tweak) == 0);
+    CHECK(ecount == 2);
+    /* Only pubkey part of keypair invalid */
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    memset(&keypair.data[32], 0, 64);
+    CHECK(secp256k1_keypair_xonly_tweak_add(verify, &keypair, tweak) == 0);
+    CHECK(ecount == 3);
+
+    /* Check that the keypair_tweak_add implementation is correct */
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    for (i = 0; i < count; i++) {
+        secp256k1_xonly_pubkey internal_pk;
+        secp256k1_xonly_pubkey output_pk;
+        secp256k1_pubkey output_pk_xy;
+        secp256k1_pubkey output_pk_expected;
+        unsigned char pk32[32];
+        int pk_parity;
+
+        secp256k1_rand256(tweak);
+        CHECK(secp256k1_keypair_xonly_pub(ctx, &internal_pk, NULL, &keypair) == 1);
+        CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
+        CHECK(secp256k1_keypair_xonly_pub(ctx, &output_pk, &pk_parity, &keypair) == 1);
+
+        /* Check that it passes xonly_pubkey_tweak_add_check */
+        CHECK(secp256k1_xonly_pubkey_serialize(ctx, pk32, &output_pk) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, pk32, pk_parity, &internal_pk, tweak) == 1);
+
+        /* Check that the resulting pubkey matches xonly_pubkey_tweak_add */
+        CHECK(secp256k1_keypair_pub(ctx, &output_pk_xy, &keypair) == 1);
+        CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk_expected, &internal_pk, tweak) == 1);
+        CHECK(memcmp(&output_pk_xy, &output_pk_expected, sizeof(output_pk_xy)) == 0);
+
+        /* Check that the secret key in the keypair is tweaked correctly */
+        CHECK(secp256k1_ec_pubkey_create(ctx, &output_pk_expected, &keypair.data[0]) == 1);
+        CHECK(memcmp(&output_pk_xy, &output_pk_expected, sizeof(output_pk_xy)) == 0);
+    }
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(verify);
+}
+
+void run_extrakeys_tests(void) {
+    /* xonly key test cases */
+    test_xonly_pubkey();
+    test_xonly_pubkey_tweak();
+    test_xonly_pubkey_tweak_check();
+    test_xonly_pubkey_tweak_recursive();
+
+    /* keypair tests */
+    test_keypair();
+    test_keypair_add();
+}
+
+#endif
diff --git a/src/secp256k1/src/modules/schnorrsig/Makefile.am.include b/src/secp256k1/src/modules/schnorrsig/Makefile.am.include
new file mode 100644
index 0000000000..a82bafe43f
--- /dev/null
+++ b/src/secp256k1/src/modules/schnorrsig/Makefile.am.include
@@ -0,0 +1,8 @@
+include_HEADERS += include/secp256k1_schnorrsig.h
+noinst_HEADERS += src/modules/schnorrsig/main_impl.h
+noinst_HEADERS += src/modules/schnorrsig/tests_impl.h
+if USE_BENCHMARK
+noinst_PROGRAMS += bench_schnorrsig
+bench_schnorrsig_SOURCES = src/bench_schnorrsig.c
+bench_schnorrsig_LDADD = libsecp256k1.la $(SECP_LIBS) $(COMMON_LIB)
+endif
diff --git a/src/secp256k1/src/modules/schnorrsig/main_impl.h b/src/secp256k1/src/modules/schnorrsig/main_impl.h
new file mode 100644
index 0000000000..a0218f881a
--- /dev/null
+++ b/src/secp256k1/src/modules/schnorrsig/main_impl.h
@@ -0,0 +1,238 @@
+/**********************************************************************
+ * Copyright (c) 2018-2020 Andrew Poelstra, Jonas Nick                *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_SCHNORRSIG_MAIN_
+#define _SECP256K1_MODULE_SCHNORRSIG_MAIN_
+
+#include "include/secp256k1.h"
+#include "include/secp256k1_schnorrsig.h"
+#include "hash.h"
+
+/* Initializes SHA256 with fixed midstate. This midstate was computed by applying
+ * SHA256 to SHA256("BIP0340/nonce")||SHA256("BIP0340/nonce"). */
+static void secp256k1_nonce_function_bip340_sha256_tagged(secp256k1_sha256 *sha) {
+    secp256k1_sha256_initialize(sha);
+    sha->s[0] = 0x46615b35ul;
+    sha->s[1] = 0xf4bfbff7ul;
+    sha->s[2] = 0x9f8dc671ul;
+    sha->s[3] = 0x83627ab3ul;
+    sha->s[4] = 0x60217180ul;
+    sha->s[5] = 0x57358661ul;
+    sha->s[6] = 0x21a29e54ul;
+    sha->s[7] = 0x68b07b4cul;
+
+    sha->bytes = 64;
+}
+
+/* Initializes SHA256 with fixed midstate. This midstate was computed by applying
+ * SHA256 to SHA256("BIP0340/aux")||SHA256("BIP0340/aux"). */
+static void secp256k1_nonce_function_bip340_sha256_tagged_aux(secp256k1_sha256 *sha) {
+    secp256k1_sha256_initialize(sha);
+    sha->s[0] = 0x24dd3219ul;
+    sha->s[1] = 0x4eba7e70ul;
+    sha->s[2] = 0xca0fabb9ul;
+    sha->s[3] = 0x0fa3166dul;
+    sha->s[4] = 0x3afbe4b1ul;
+    sha->s[5] = 0x4c44df97ul;
+    sha->s[6] = 0x4aac2739ul;
+    sha->s[7] = 0x249e850aul;
+
+    sha->bytes = 64;
+}
+
+/* algo16 argument for nonce_function_bip340 to derive the nonce exactly as stated in BIP-340
+ * by using the correct tagged hash function. */
+static const unsigned char bip340_algo16[16] = "BIP0340/nonce\0\0\0";
+
+static int nonce_function_bip340(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *xonly_pk32, const unsigned char *algo16, void *data) {
+    secp256k1_sha256 sha;
+    unsigned char masked_key[32];
+    int i;
+
+    if (algo16 == NULL) {
+        return 0;
+    }
+
+    if (data != NULL) {
+        secp256k1_nonce_function_bip340_sha256_tagged_aux(&sha);
+        secp256k1_sha256_write(&sha, data, 32);
+        secp256k1_sha256_finalize(&sha, masked_key);
+        for (i = 0; i < 32; i++) {
+            masked_key[i] ^= key32[i];
+        }
+    }
+
+    /* Tag the hash with algo16 which is important to avoid nonce reuse across
+     * algorithms. If this nonce function is used in BIP-340 signing as defined
+     * in the spec, an optimized tagging implementation is used. */
+    if (memcmp(algo16, bip340_algo16, 16) == 0) {
+        secp256k1_nonce_function_bip340_sha256_tagged(&sha);
+    } else {
+        int algo16_len = 16;
+        /* Remove terminating null bytes */
+        while (algo16_len > 0 && !algo16[algo16_len - 1]) {
+            algo16_len--;
+        }
+        secp256k1_sha256_initialize_tagged(&sha, algo16, algo16_len);
+    }
+
+    /* Hash (masked-)key||pk||msg using the tagged hash as per the spec */
+    if (data != NULL) {
+        secp256k1_sha256_write(&sha, masked_key, 32);
+    } else {
+        secp256k1_sha256_write(&sha, key32, 32);
+    }
+    secp256k1_sha256_write(&sha, xonly_pk32, 32);
+    secp256k1_sha256_write(&sha, msg32, 32);
+    secp256k1_sha256_finalize(&sha, nonce32);
+    return 1;
+}
+
+const secp256k1_nonce_function_hardened secp256k1_nonce_function_bip340 = nonce_function_bip340;
+
+/* Initializes SHA256 with fixed midstate. This midstate was computed by applying
+ * SHA256 to SHA256("BIP0340/challenge")||SHA256("BIP0340/challenge"). */
+static void secp256k1_schnorrsig_sha256_tagged(secp256k1_sha256 *sha) {
+    secp256k1_sha256_initialize(sha);
+    sha->s[0] = 0x9cecba11ul;
+    sha->s[1] = 0x23925381ul;
+    sha->s[2] = 0x11679112ul;
+    sha->s[3] = 0xd1627e0ful;
+    sha->s[4] = 0x97c87550ul;
+    sha->s[5] = 0x003cc765ul;
+    sha->s[6] = 0x90f61164ul;
+    sha->s[7] = 0x33e9b66aul;
+    sha->bytes = 64;
+}
+
+int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, unsigned char *sig64, const unsigned char *msg32, const secp256k1_keypair *keypair, secp256k1_nonce_function_hardened noncefp, void *ndata) {
+    secp256k1_scalar sk;
+    secp256k1_scalar e;
+    secp256k1_scalar k;
+    secp256k1_gej rj;
+    secp256k1_ge pk;
+    secp256k1_ge r;
+    secp256k1_sha256 sha;
+    unsigned char buf[32] = { 0 };
+    unsigned char pk_buf[32];
+    unsigned char seckey[32];
+    int ret = 1;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(sig64 != NULL);
+    ARG_CHECK(msg32 != NULL);
+    ARG_CHECK(keypair != NULL);
+
+    if (noncefp == NULL) {
+        noncefp = secp256k1_nonce_function_bip340;
+    }
+
+    ret &= secp256k1_keypair_load(ctx, &sk, &pk, keypair);
+    /* Because we are signing for a x-only pubkey, the secret key is negated
+     * before signing if the point corresponding to the secret key does not
+     * have an even Y. */
+    if (secp256k1_fe_is_odd(&pk.y)) {
+        secp256k1_scalar_negate(&sk, &sk);
+    }
+
+    secp256k1_scalar_get_b32(seckey, &sk);
+    secp256k1_fe_get_b32(pk_buf, &pk.x);
+    ret &= !!noncefp(buf, msg32, seckey, pk_buf, bip340_algo16, ndata);
+    secp256k1_scalar_set_b32(&k, buf, NULL);
+    ret &= !secp256k1_scalar_is_zero(&k);
+    secp256k1_scalar_cmov(&k, &secp256k1_scalar_one, !ret);
+
+    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &k);
+    secp256k1_ge_set_gej(&r, &rj);
+
+    /* We declassify r to allow using it as a branch point. This is fine
+     * because r is not a secret. */
+    secp256k1_declassify(ctx, &r, sizeof(r));
+    secp256k1_fe_normalize_var(&r.y);
+    if (secp256k1_fe_is_odd(&r.y)) {
+        secp256k1_scalar_negate(&k, &k);
+    }
+    secp256k1_fe_normalize_var(&r.x);
+    secp256k1_fe_get_b32(&sig64[0], &r.x);
+
+    /* tagged hash(r.x, pk.x, msg32) */
+    secp256k1_schnorrsig_sha256_tagged(&sha);
+    secp256k1_sha256_write(&sha, &sig64[0], 32);
+    secp256k1_sha256_write(&sha, pk_buf, sizeof(pk_buf));
+    secp256k1_sha256_write(&sha, msg32, 32);
+    secp256k1_sha256_finalize(&sha, buf);
+
+    /* Set scalar e to the challenge hash modulo the curve order as per
+     * BIP340. */
+    secp256k1_scalar_set_b32(&e, buf, NULL);
+    secp256k1_scalar_mul(&e, &e, &sk);
+    secp256k1_scalar_add(&e, &e, &k);
+    secp256k1_scalar_get_b32(&sig64[32], &e);
+
+    memczero(sig64, 64, !ret);
+    secp256k1_scalar_clear(&k);
+    secp256k1_scalar_clear(&sk);
+    memset(seckey, 0, sizeof(seckey));
+
+    return ret;
+}
+
+int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const unsigned char *sig64, const unsigned char *msg32, const secp256k1_xonly_pubkey *pubkey) {
+    secp256k1_scalar s;
+    secp256k1_scalar e;
+    secp256k1_gej rj;
+    secp256k1_ge pk;
+    secp256k1_gej pkj;
+    secp256k1_fe rx;
+    secp256k1_ge r;
+    secp256k1_sha256 sha;
+    unsigned char buf[32];
+    int overflow;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(sig64 != NULL);
+    ARG_CHECK(msg32 != NULL);
+    ARG_CHECK(pubkey != NULL);
+
+    if (!secp256k1_fe_set_b32(&rx, &sig64[0])) {
+        return 0;
+    }
+
+    secp256k1_scalar_set_b32(&s, &sig64[32], &overflow);
+    if (overflow) {
+        return 0;
+    }
+
+    if (!secp256k1_xonly_pubkey_load(ctx, &pk, pubkey)) {
+        return 0;
+    }
+
+    secp256k1_schnorrsig_sha256_tagged(&sha);
+    secp256k1_sha256_write(&sha, &sig64[0], 32);
+    secp256k1_fe_get_b32(buf, &pk.x);
+    secp256k1_sha256_write(&sha, buf, sizeof(buf));
+    secp256k1_sha256_write(&sha, msg32, 32);
+    secp256k1_sha256_finalize(&sha, buf);
+    secp256k1_scalar_set_b32(&e, buf, NULL);
+
+    /* Compute rj =  s*G + (-e)*pkj */
+    secp256k1_scalar_negate(&e, &e);
+    secp256k1_gej_set_ge(&pkj, &pk);
+    secp256k1_ecmult(&ctx->ecmult_ctx, &rj, &pkj, &e, &s);
+
+    secp256k1_ge_set_gej_var(&r, &rj);
+    if (secp256k1_ge_is_infinity(&r)) {
+        return 0;
+    }
+
+    secp256k1_fe_normalize_var(&r.y);
+    return !secp256k1_fe_is_odd(&r.y) &&
+           secp256k1_fe_equal_var(&rx, &r.x);
+}
+
+#endif
diff --git a/src/secp256k1/src/modules/schnorrsig/tests_impl.h b/src/secp256k1/src/modules/schnorrsig/tests_impl.h
new file mode 100644
index 0000000000..88d8f56404
--- /dev/null
+++ b/src/secp256k1/src/modules/schnorrsig/tests_impl.h
@@ -0,0 +1,806 @@
+/**********************************************************************
+ * Copyright (c) 2018-2020 Andrew Poelstra, Jonas Nick                *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_SCHNORRSIG_TESTS_
+#define _SECP256K1_MODULE_SCHNORRSIG_TESTS_
+
+#include "secp256k1_schnorrsig.h"
+
+/* Checks that a bit flip in the n_flip-th argument (that has n_bytes many
+ * bytes) changes the hash function
+ */
+void nonce_function_bip340_bitflip(unsigned char **args, size_t n_flip, size_t n_bytes) {
+    unsigned char nonces[2][32];
+    CHECK(nonce_function_bip340(nonces[0], args[0], args[1], args[2], args[3], args[4]) == 1);
+    secp256k1_rand_flip(args[n_flip], n_bytes);
+    CHECK(nonce_function_bip340(nonces[1], args[0], args[1], args[2], args[3], args[4]) == 1);
+    CHECK(memcmp(nonces[0], nonces[1], 32) != 0);
+}
+
+/* Tests for the equality of two sha256 structs. This function only produces a
+ * correct result if an integer multiple of 64 many bytes have been written
+ * into the hash functions. */
+void test_sha256_eq(const secp256k1_sha256 *sha1, const secp256k1_sha256 *sha2) {
+    /* Is buffer fully consumed? */
+    CHECK((sha1->bytes & 0x3F) == 0);
+
+    CHECK(sha1->bytes == sha2->bytes);
+    CHECK(memcmp(sha1->s, sha2->s, sizeof(sha1->s)) == 0);
+}
+
+void run_nonce_function_bip340_tests(void) {
+    unsigned char tag[13] = "BIP0340/nonce";
+    unsigned char aux_tag[11] = "BIP0340/aux";
+    unsigned char algo16[16] = "BIP0340/nonce\0\0\0";
+    secp256k1_sha256 sha;
+    secp256k1_sha256 sha_optimized;
+    unsigned char nonce[32];
+    unsigned char msg[32];
+    unsigned char key[32];
+    unsigned char pk[32];
+    unsigned char aux_rand[32];
+    unsigned char *args[5];
+    int i;
+
+    /* Check that hash initialized by
+     * secp256k1_nonce_function_bip340_sha256_tagged has the expected
+     * state. */
+    secp256k1_sha256_initialize_tagged(&sha, tag, sizeof(tag));
+    secp256k1_nonce_function_bip340_sha256_tagged(&sha_optimized);
+    test_sha256_eq(&sha, &sha_optimized);
+
+   /* Check that hash initialized by
+    * secp256k1_nonce_function_bip340_sha256_tagged_aux has the expected
+    * state. */
+    secp256k1_sha256_initialize_tagged(&sha, aux_tag, sizeof(aux_tag));
+    secp256k1_nonce_function_bip340_sha256_tagged_aux(&sha_optimized);
+    test_sha256_eq(&sha, &sha_optimized);
+
+    secp256k1_rand256(msg);
+    secp256k1_rand256(key);
+    secp256k1_rand256(pk);
+    secp256k1_rand256(aux_rand);
+
+    /* Check that a bitflip in an argument results in different nonces. */
+    args[0] = msg;
+    args[1] = key;
+    args[2] = pk;
+    args[3] = algo16;
+    args[4] = aux_rand;
+    for (i = 0; i < count; i++) {
+        nonce_function_bip340_bitflip(args, 0, 32);
+        nonce_function_bip340_bitflip(args, 1, 32);
+        nonce_function_bip340_bitflip(args, 2, 32);
+        /* Flip algo16 special case "BIP0340/nonce" */
+        nonce_function_bip340_bitflip(args, 3, 16);
+        /* Flip algo16 again */
+        nonce_function_bip340_bitflip(args, 3, 16);
+        nonce_function_bip340_bitflip(args, 4, 32);
+    }
+
+    /* NULL algo16 is disallowed */
+    CHECK(nonce_function_bip340(nonce, msg, key, pk, NULL, NULL) == 0);
+    /* Empty algo16 is fine */
+    memset(algo16, 0x00, 16);
+    CHECK(nonce_function_bip340(nonce, msg, key, pk, algo16, NULL) == 1);
+    /* algo16 with terminating null bytes is fine */
+    algo16[1] = 65;
+    CHECK(nonce_function_bip340(nonce, msg, key, pk, algo16, NULL) == 1);
+    /* Other algo16 is fine */
+    memset(algo16, 0xFF, 16);
+    CHECK(nonce_function_bip340(nonce, msg, key, pk, algo16, NULL) == 1);
+
+    /* NULL aux_rand argument is allowed. */
+    CHECK(nonce_function_bip340(nonce, msg, key, pk, algo16, NULL) == 1);
+}
+
+void test_schnorrsig_api(void) {
+    unsigned char sk1[32];
+    unsigned char sk2[32];
+    unsigned char sk3[32];
+    unsigned char msg[32];
+    secp256k1_keypair keypairs[3];
+    secp256k1_keypair invalid_keypair = { 0 };
+    secp256k1_xonly_pubkey pk[3];
+    secp256k1_xonly_pubkey zero_pk;
+    unsigned char sig[64];
+
+    /** setup **/
+    secp256k1_context *none = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+    secp256k1_context *sign = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    secp256k1_context *vrfy = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
+    secp256k1_context *both = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
+    int ecount;
+
+    secp256k1_context_set_error_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(vrfy, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(both, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(vrfy, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(both, counting_illegal_callback_fn, &ecount);
+
+    secp256k1_rand256(sk1);
+    secp256k1_rand256(sk2);
+    secp256k1_rand256(sk3);
+    secp256k1_rand256(msg);
+    CHECK(secp256k1_keypair_create(ctx, &keypairs[0], sk1) == 1);
+    CHECK(secp256k1_keypair_create(ctx, &keypairs[1], sk2) == 1);
+    CHECK(secp256k1_keypair_create(ctx, &keypairs[2], sk3) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[0], NULL, &keypairs[0]) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[1], NULL, &keypairs[1]) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk[2], NULL, &keypairs[2]) == 1);
+    memset(&zero_pk, 0, sizeof(zero_pk));
+
+    /** main test body **/
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_sign(none, sig, msg, &keypairs[0], NULL, NULL) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_sign(vrfy, sig, msg, &keypairs[0], NULL, NULL) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_sign(sign, sig, msg, &keypairs[0], NULL, NULL) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_sign(sign, NULL, msg, &keypairs[0], NULL, NULL) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_sign(sign, sig, NULL, &keypairs[0], NULL, NULL) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_schnorrsig_sign(sign, sig, msg, NULL, NULL, NULL) == 0);
+    CHECK(ecount == 5);
+    CHECK(secp256k1_schnorrsig_sign(sign, sig, msg, &invalid_keypair, NULL, NULL) == 0);
+    CHECK(ecount == 6);
+
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_sign(sign, sig, msg, &keypairs[0], NULL, NULL) == 1);
+    CHECK(secp256k1_schnorrsig_verify(none, sig, msg, &pk[0]) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_verify(sign, sig, msg, &pk[0]) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, sig, msg, &pk[0]) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, NULL, msg, &pk[0]) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, sig, NULL, &pk[0]) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, sig, msg, NULL) == 0);
+    CHECK(ecount == 5);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, sig, msg, &zero_pk) == 0);
+    CHECK(ecount == 6);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(vrfy);
+    secp256k1_context_destroy(both);
+}
+
+/* Checks that hash initialized by secp256k1_schnorrsig_sha256_tagged has the
+ * expected state. */
+void test_schnorrsig_sha256_tagged(void) {
+    char tag[17] = "BIP0340/challenge";
+    secp256k1_sha256 sha;
+    secp256k1_sha256 sha_optimized;
+
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char *) tag, sizeof(tag));
+    secp256k1_schnorrsig_sha256_tagged(&sha_optimized);
+    test_sha256_eq(&sha, &sha_optimized);
+}
+
+/* Helper function for schnorrsig_bip_vectors
+ * Signs the message and checks that it's the same as expected_sig. */
+void test_schnorrsig_bip_vectors_check_signing(const unsigned char *sk, const unsigned char *pk_serialized, unsigned char *aux_rand, const unsigned char *msg, const unsigned char *expected_sig) {
+    unsigned char sig[64];
+    secp256k1_keypair keypair;
+    secp256k1_xonly_pubkey pk, pk_expected;
+
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, NULL, aux_rand));
+    CHECK(memcmp(sig, expected_sig, 64) == 0);
+
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk_expected, pk_serialized));
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
+    CHECK(memcmp(&pk, &pk_expected, sizeof(pk)) == 0);
+    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, &pk));
+}
+
+/* Helper function for schnorrsig_bip_vectors
+ * Checks that both verify and verify_batch (TODO) return the same value as expected. */
+void test_schnorrsig_bip_vectors_check_verify(const unsigned char *pk_serialized, const unsigned char *msg32, const unsigned char *sig, int expected) {
+    secp256k1_xonly_pubkey pk;
+
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk, pk_serialized));
+    CHECK(expected == secp256k1_schnorrsig_verify(ctx, sig, msg32, &pk));
+}
+
+/* Test vectors according to BIP-340 ("Schnorr Signatures for secp256k1"). See
+ * https://github.com/bitcoin/bips/blob/master/bip-0340/test-vectors.csv. */
+void test_schnorrsig_bip_vectors(void) {
+    {
+        /* Test vector 0 */
+        const unsigned char sk[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03
+        };
+        const unsigned char pk[32] = {
+            0xF9, 0x30, 0x8A, 0x01, 0x92, 0x58, 0xC3, 0x10,
+            0x49, 0x34, 0x4F, 0x85, 0xF8, 0x9D, 0x52, 0x29,
+            0xB5, 0x31, 0xC8, 0x45, 0x83, 0x6F, 0x99, 0xB0,
+            0x86, 0x01, 0xF1, 0x13, 0xBC, 0xE0, 0x36, 0xF9
+        };
+        unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        };
+        const unsigned char msg[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        };
+        const unsigned char sig[64] = {
+            0xE9, 0x07, 0x83, 0x1F, 0x80, 0x84, 0x8D, 0x10,
+            0x69, 0xA5, 0x37, 0x1B, 0x40, 0x24, 0x10, 0x36,
+            0x4B, 0xDF, 0x1C, 0x5F, 0x83, 0x07, 0xB0, 0x08,
+            0x4C, 0x55, 0xF1, 0xCE, 0x2D, 0xCA, 0x82, 0x15,
+            0x25, 0xF6, 0x6A, 0x4A, 0x85, 0xEA, 0x8B, 0x71,
+            0xE4, 0x82, 0xA7, 0x4F, 0x38, 0x2D, 0x2C, 0xE5,
+            0xEB, 0xEE, 0xE8, 0xFD, 0xB2, 0x17, 0x2F, 0x47,
+            0x7D, 0xF4, 0x90, 0x0D, 0x31, 0x05, 0x36, 0xC0
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 1 */
+        const unsigned char sk[32] = {
+            0xB7, 0xE1, 0x51, 0x62, 0x8A, 0xED, 0x2A, 0x6A,
+            0xBF, 0x71, 0x58, 0x80, 0x9C, 0xF4, 0xF3, 0xC7,
+            0x62, 0xE7, 0x16, 0x0F, 0x38, 0xB4, 0xDA, 0x56,
+            0xA7, 0x84, 0xD9, 0x04, 0x51, 0x90, 0xCF, 0xEF
+        };
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        unsigned char aux_rand[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x68, 0x96, 0xBD, 0x60, 0xEE, 0xAE, 0x29, 0x6D,
+            0xB4, 0x8A, 0x22, 0x9F, 0xF7, 0x1D, 0xFE, 0x07,
+            0x1B, 0xDE, 0x41, 0x3E, 0x6D, 0x43, 0xF9, 0x17,
+            0xDC, 0x8D, 0xCF, 0x8C, 0x78, 0xDE, 0x33, 0x41,
+            0x89, 0x06, 0xD1, 0x1A, 0xC9, 0x76, 0xAB, 0xCC,
+            0xB2, 0x0B, 0x09, 0x12, 0x92, 0xBF, 0xF4, 0xEA,
+            0x89, 0x7E, 0xFC, 0xB6, 0x39, 0xEA, 0x87, 0x1C,
+            0xFA, 0x95, 0xF6, 0xDE, 0x33, 0x9E, 0x4B, 0x0A
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 2 */
+        const unsigned char sk[32] = {
+            0xC9, 0x0F, 0xDA, 0xA2, 0x21, 0x68, 0xC2, 0x34,
+            0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+            0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74,
+            0x02, 0x0B, 0xBE, 0xA6, 0x3B, 0x14, 0xE5, 0xC9
+        };
+        const unsigned char pk[32] = {
+            0xDD, 0x30, 0x8A, 0xFE, 0xC5, 0x77, 0x7E, 0x13,
+            0x12, 0x1F, 0xA7, 0x2B, 0x9C, 0xC1, 0xB7, 0xCC,
+            0x01, 0x39, 0x71, 0x53, 0x09, 0xB0, 0x86, 0xC9,
+            0x60, 0xE1, 0x8F, 0xD9, 0x69, 0x77, 0x4E, 0xB8
+        };
+        unsigned char aux_rand[32] = {
+            0xC8, 0x7A, 0xA5, 0x38, 0x24, 0xB4, 0xD7, 0xAE,
+            0x2E, 0xB0, 0x35, 0xA2, 0xB5, 0xBB, 0xBC, 0xCC,
+            0x08, 0x0E, 0x76, 0xCD, 0xC6, 0xD1, 0x69, 0x2C,
+            0x4B, 0x0B, 0x62, 0xD7, 0x98, 0xE6, 0xD9, 0x06
+        };
+        const unsigned char msg[32] = {
+            0x7E, 0x2D, 0x58, 0xD8, 0xB3, 0xBC, 0xDF, 0x1A,
+            0xBA, 0xDE, 0xC7, 0x82, 0x90, 0x54, 0xF9, 0x0D,
+            0xDA, 0x98, 0x05, 0xAA, 0xB5, 0x6C, 0x77, 0x33,
+            0x30, 0x24, 0xB9, 0xD0, 0xA5, 0x08, 0xB7, 0x5C
+        };
+        const unsigned char sig[64] = {
+            0x58, 0x31, 0xAA, 0xEE, 0xD7, 0xB4, 0x4B, 0xB7,
+            0x4E, 0x5E, 0xAB, 0x94, 0xBA, 0x9D, 0x42, 0x94,
+            0xC4, 0x9B, 0xCF, 0x2A, 0x60, 0x72, 0x8D, 0x8B,
+            0x4C, 0x20, 0x0F, 0x50, 0xDD, 0x31, 0x3C, 0x1B,
+            0xAB, 0x74, 0x58, 0x79, 0xA5, 0xAD, 0x95, 0x4A,
+            0x72, 0xC4, 0x5A, 0x91, 0xC3, 0xA5, 0x1D, 0x3C,
+            0x7A, 0xDE, 0xA9, 0x8D, 0x82, 0xF8, 0x48, 0x1E,
+            0x0E, 0x1E, 0x03, 0x67, 0x4A, 0x6F, 0x3F, 0xB7
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 3 */
+        const unsigned char sk[32] = {
+            0x0B, 0x43, 0x2B, 0x26, 0x77, 0x93, 0x73, 0x81,
+            0xAE, 0xF0, 0x5B, 0xB0, 0x2A, 0x66, 0xEC, 0xD0,
+            0x12, 0x77, 0x30, 0x62, 0xCF, 0x3F, 0xA2, 0x54,
+            0x9E, 0x44, 0xF5, 0x8E, 0xD2, 0x40, 0x17, 0x10
+        };
+        const unsigned char pk[32] = {
+            0x25, 0xD1, 0xDF, 0xF9, 0x51, 0x05, 0xF5, 0x25,
+            0x3C, 0x40, 0x22, 0xF6, 0x28, 0xA9, 0x96, 0xAD,
+            0x3A, 0x0D, 0x95, 0xFB, 0xF2, 0x1D, 0x46, 0x8A,
+            0x1B, 0x33, 0xF8, 0xC1, 0x60, 0xD8, 0xF5, 0x17
+        };
+        unsigned char aux_rand[32] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+        };
+        const unsigned char msg[32] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+        };
+        const unsigned char sig[64] = {
+            0x7E, 0xB0, 0x50, 0x97, 0x57, 0xE2, 0x46, 0xF1,
+            0x94, 0x49, 0x88, 0x56, 0x51, 0x61, 0x1C, 0xB9,
+            0x65, 0xEC, 0xC1, 0xA1, 0x87, 0xDD, 0x51, 0xB6,
+            0x4F, 0xDA, 0x1E, 0xDC, 0x96, 0x37, 0xD5, 0xEC,
+            0x97, 0x58, 0x2B, 0x9C, 0xB1, 0x3D, 0xB3, 0x93,
+            0x37, 0x05, 0xB3, 0x2B, 0xA9, 0x82, 0xAF, 0x5A,
+            0xF2, 0x5F, 0xD7, 0x88, 0x81, 0xEB, 0xB3, 0x27,
+            0x71, 0xFC, 0x59, 0x22, 0xEF, 0xC6, 0x6E, 0xA3
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, aux_rand, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 4 */
+        const unsigned char pk[32] = {
+            0xD6, 0x9C, 0x35, 0x09, 0xBB, 0x99, 0xE4, 0x12,
+            0xE6, 0x8B, 0x0F, 0xE8, 0x54, 0x4E, 0x72, 0x83,
+            0x7D, 0xFA, 0x30, 0x74, 0x6D, 0x8B, 0xE2, 0xAA,
+            0x65, 0x97, 0x5F, 0x29, 0xD2, 0x2D, 0xC7, 0xB9
+        };
+        const unsigned char msg[32] = {
+            0x4D, 0xF3, 0xC3, 0xF6, 0x8F, 0xCC, 0x83, 0xB2,
+            0x7E, 0x9D, 0x42, 0xC9, 0x04, 0x31, 0xA7, 0x24,
+            0x99, 0xF1, 0x78, 0x75, 0xC8, 0x1A, 0x59, 0x9B,
+            0x56, 0x6C, 0x98, 0x89, 0xB9, 0x69, 0x67, 0x03
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x3B, 0x78, 0xCE, 0x56, 0x3F,
+            0x89, 0xA0, 0xED, 0x94, 0x14, 0xF5, 0xAA, 0x28,
+            0xAD, 0x0D, 0x96, 0xD6, 0x79, 0x5F, 0x9C, 0x63,
+            0x76, 0xAF, 0xB1, 0x54, 0x8A, 0xF6, 0x03, 0xB3,
+            0xEB, 0x45, 0xC9, 0xF8, 0x20, 0x7D, 0xEE, 0x10,
+            0x60, 0xCB, 0x71, 0xC0, 0x4E, 0x80, 0xF5, 0x93,
+            0x06, 0x0B, 0x07, 0xD2, 0x83, 0x08, 0xD7, 0xF4
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 5 */
+        const unsigned char pk[32] = {
+            0xEE, 0xFD, 0xEA, 0x4C, 0xDB, 0x67, 0x77, 0x50,
+            0xA4, 0x20, 0xFE, 0xE8, 0x07, 0xEA, 0xCF, 0x21,
+            0xEB, 0x98, 0x98, 0xAE, 0x79, 0xB9, 0x76, 0x87,
+            0x66, 0xE4, 0xFA, 0xA0, 0x4A, 0x2D, 0x4A, 0x34
+        };
+        secp256k1_xonly_pubkey pk_parsed;
+        /* No need to check the signature of the test vector as parsing the pubkey already fails */
+        CHECK(!secp256k1_xonly_pubkey_parse(ctx, &pk_parsed, pk));
+    }
+    {
+        /* Test vector 6 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0xFF, 0xF9, 0x7B, 0xD5, 0x75, 0x5E, 0xEE, 0xA4,
+            0x20, 0x45, 0x3A, 0x14, 0x35, 0x52, 0x35, 0xD3,
+            0x82, 0xF6, 0x47, 0x2F, 0x85, 0x68, 0xA1, 0x8B,
+            0x2F, 0x05, 0x7A, 0x14, 0x60, 0x29, 0x75, 0x56,
+            0x3C, 0xC2, 0x79, 0x44, 0x64, 0x0A, 0xC6, 0x07,
+            0xCD, 0x10, 0x7A, 0xE1, 0x09, 0x23, 0xD9, 0xEF,
+            0x7A, 0x73, 0xC6, 0x43, 0xE1, 0x66, 0xBE, 0x5E,
+            0xBE, 0xAF, 0xA3, 0x4B, 0x1A, 0xC5, 0x53, 0xE2
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 7 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x1F, 0xA6, 0x2E, 0x33, 0x1E, 0xDB, 0xC2, 0x1C,
+            0x39, 0x47, 0x92, 0xD2, 0xAB, 0x11, 0x00, 0xA7,
+            0xB4, 0x32, 0xB0, 0x13, 0xDF, 0x3F, 0x6F, 0xF4,
+            0xF9, 0x9F, 0xCB, 0x33, 0xE0, 0xE1, 0x51, 0x5F,
+            0x28, 0x89, 0x0B, 0x3E, 0xDB, 0x6E, 0x71, 0x89,
+            0xB6, 0x30, 0x44, 0x8B, 0x51, 0x5C, 0xE4, 0xF8,
+            0x62, 0x2A, 0x95, 0x4C, 0xFE, 0x54, 0x57, 0x35,
+            0xAA, 0xEA, 0x51, 0x34, 0xFC, 0xCD, 0xB2, 0xBD
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 8 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x6C, 0xFF, 0x5C, 0x3B, 0xA8, 0x6C, 0x69, 0xEA,
+            0x4B, 0x73, 0x76, 0xF3, 0x1A, 0x9B, 0xCB, 0x4F,
+            0x74, 0xC1, 0x97, 0x60, 0x89, 0xB2, 0xD9, 0x96,
+            0x3D, 0xA2, 0xE5, 0x54, 0x3E, 0x17, 0x77, 0x69,
+            0x96, 0x17, 0x64, 0xB3, 0xAA, 0x9B, 0x2F, 0xFC,
+            0xB6, 0xEF, 0x94, 0x7B, 0x68, 0x87, 0xA2, 0x26,
+            0xE8, 0xD7, 0xC9, 0x3E, 0x00, 0xC5, 0xED, 0x0C,
+            0x18, 0x34, 0xFF, 0x0D, 0x0C, 0x2E, 0x6D, 0xA6
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 9 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x12, 0x3D, 0xDA, 0x83, 0x28, 0xAF, 0x9C, 0x23,
+            0xA9, 0x4C, 0x1F, 0xEE, 0xCF, 0xD1, 0x23, 0xBA,
+            0x4F, 0xB7, 0x34, 0x76, 0xF0, 0xD5, 0x94, 0xDC,
+            0xB6, 0x5C, 0x64, 0x25, 0xBD, 0x18, 0x60, 0x51
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 10 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+            0x76, 0x15, 0xFB, 0xAF, 0x5A, 0xE2, 0x88, 0x64,
+            0x01, 0x3C, 0x09, 0x97, 0x42, 0xDE, 0xAD, 0xB4,
+            0xDB, 0xA8, 0x7F, 0x11, 0xAC, 0x67, 0x54, 0xF9,
+            0x37, 0x80, 0xD5, 0xA1, 0x83, 0x7C, 0xF1, 0x97
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 11 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x4A, 0x29, 0x8D, 0xAC, 0xAE, 0x57, 0x39, 0x5A,
+            0x15, 0xD0, 0x79, 0x5D, 0xDB, 0xFD, 0x1D, 0xCB,
+            0x56, 0x4D, 0xA8, 0x2B, 0x0F, 0x26, 0x9B, 0xC7,
+            0x0A, 0x74, 0xF8, 0x22, 0x04, 0x29, 0xBA, 0x1D,
+            0x69, 0xE8, 0x9B, 0x4C, 0x55, 0x64, 0xD0, 0x03,
+            0x49, 0x10, 0x6B, 0x84, 0x97, 0x78, 0x5D, 0xD7,
+            0xD1, 0xD7, 0x13, 0xA8, 0xAE, 0x82, 0xB3, 0x2F,
+            0xA7, 0x9D, 0x5F, 0x7F, 0xC4, 0x07, 0xD3, 0x9B
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 12 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFE, 0xFF, 0xFF, 0xFC, 0x2F,
+            0x69, 0xE8, 0x9B, 0x4C, 0x55, 0x64, 0xD0, 0x03,
+            0x49, 0x10, 0x6B, 0x84, 0x97, 0x78, 0x5D, 0xD7,
+            0xD1, 0xD7, 0x13, 0xA8, 0xAE, 0x82, 0xB3, 0x2F,
+            0xA7, 0x9D, 0x5F, 0x7F, 0xC4, 0x07, 0xD3, 0x9B
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 13 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x6C, 0xFF, 0x5C, 0x3B, 0xA8, 0x6C, 0x69, 0xEA,
+            0x4B, 0x73, 0x76, 0xF3, 0x1A, 0x9B, 0xCB, 0x4F,
+            0x74, 0xC1, 0x97, 0x60, 0x89, 0xB2, 0xD9, 0x96,
+            0x3D, 0xA2, 0xE5, 0x54, 0x3E, 0x17, 0x77, 0x69,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE,
+            0xBA, 0xAE, 0xDC, 0xE6, 0xAF, 0x48, 0xA0, 0x3B,
+            0xBF, 0xD2, 0x5E, 0x8C, 0xD0, 0x36, 0x41, 0x41
+        };
+        test_schnorrsig_bip_vectors_check_verify(pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 14 */
+        const unsigned char pk[32] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFE, 0xFF, 0xFF, 0xFC, 0x30
+        };
+        secp256k1_xonly_pubkey pk_parsed;
+        /* No need to check the signature of the test vector as parsing the pubkey already fails */
+        CHECK(!secp256k1_xonly_pubkey_parse(ctx, &pk_parsed, pk));
+    }
+}
+
+/* Nonce function that returns constant 0 */
+static int nonce_function_failing(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *xonly_pk32, const unsigned char *algo16, void *data) {
+    (void) msg32;
+    (void) key32;
+    (void) xonly_pk32;
+    (void) algo16;
+    (void) data;
+    (void) nonce32;
+    return 0;
+}
+
+/* Nonce function that sets nonce to 0 */
+static int nonce_function_0(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *xonly_pk32, const unsigned char *algo16, void *data) {
+    (void) msg32;
+    (void) key32;
+    (void) xonly_pk32;
+    (void) algo16;
+    (void) data;
+
+    memset(nonce32, 0, 32);
+    return 1;
+}
+
+/* Nonce function that sets nonce to 0xFF...0xFF */
+static int nonce_function_overflowing(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *xonly_pk32, const unsigned char *algo16, void *data) {
+    (void) msg32;
+    (void) key32;
+    (void) xonly_pk32;
+    (void) algo16;
+    (void) data;
+
+    memset(nonce32, 0xFF, 32);
+    return 1;
+}
+
+void test_schnorrsig_sign(void) {
+    unsigned char sk[32];
+    secp256k1_keypair keypair;
+    const unsigned char msg[32] = "this is a msg for a schnorrsig..";
+    unsigned char sig[64];
+    unsigned char zeros64[64] = { 0 };
+
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, NULL, NULL) == 1);
+
+    /* Test different nonce functions */
+    memset(sig, 1, sizeof(sig));
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, nonce_function_failing, NULL) == 0);
+    CHECK(memcmp(sig, zeros64, sizeof(sig)) == 0);
+    memset(&sig, 1, sizeof(sig));
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, nonce_function_0, NULL) == 0);
+    CHECK(memcmp(sig, zeros64, sizeof(sig)) == 0);
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, nonce_function_overflowing, NULL) == 1);
+    CHECK(memcmp(sig, zeros64, sizeof(sig)) != 0);
+}
+
+#define N_SIGS 3
+/* Creates N_SIGS valid signatures and verifies them with verify and
+ * verify_batch (TODO). Then flips some bits and checks that verification now
+ * fails. */
+void test_schnorrsig_sign_verify(void) {
+    unsigned char sk[32];
+    unsigned char msg[N_SIGS][32];
+    unsigned char sig[N_SIGS][64];
+    size_t i;
+    secp256k1_keypair keypair;
+    secp256k1_xonly_pubkey pk;
+    secp256k1_scalar s;
+
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk));
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &pk, NULL, &keypair));
+
+    for (i = 0; i < N_SIGS; i++) {
+        secp256k1_rand256(msg[i]);
+        CHECK(secp256k1_schnorrsig_sign(ctx, sig[i], msg[i], &keypair, NULL, NULL));
+        CHECK(secp256k1_schnorrsig_verify(ctx, sig[i], msg[i], &pk));
+    }
+
+    {
+        /* Flip a few bits in the signature and in the message and check that
+         * verify and verify_batch (TODO) fail */
+        size_t sig_idx = secp256k1_rand_int(N_SIGS);
+        size_t byte_idx = secp256k1_rand_int(32);
+        unsigned char xorbyte = secp256k1_rand_int(254)+1;
+        sig[sig_idx][byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], &pk));
+        sig[sig_idx][byte_idx] ^= xorbyte;
+
+        byte_idx = secp256k1_rand_int(32);
+        sig[sig_idx][32+byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], &pk));
+        sig[sig_idx][32+byte_idx] ^= xorbyte;
+
+        byte_idx = secp256k1_rand_int(32);
+        msg[sig_idx][byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], &pk));
+        msg[sig_idx][byte_idx] ^= xorbyte;
+
+        /* Check that above bitflips have been reversed correctly */
+        CHECK(secp256k1_schnorrsig_verify(ctx, sig[sig_idx], msg[sig_idx], &pk));
+    }
+
+    /* Test overflowing s */
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig[0], msg[0], &keypair, NULL, NULL));
+    CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], &pk));
+    memset(&sig[0][32], 0xFF, 32);
+    CHECK(!secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], &pk));
+
+    /* Test negative s */
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig[0], msg[0], &keypair, NULL, NULL));
+    CHECK(secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], &pk));
+    secp256k1_scalar_set_b32(&s, &sig[0][32], NULL);
+    secp256k1_scalar_negate(&s, &s);
+    secp256k1_scalar_get_b32(&sig[0][32], &s);
+    CHECK(!secp256k1_schnorrsig_verify(ctx, sig[0], msg[0], &pk));
+}
+#undef N_SIGS
+
+void test_schnorrsig_taproot(void) {
+    unsigned char sk[32];
+    secp256k1_keypair keypair;
+    secp256k1_xonly_pubkey internal_pk;
+    unsigned char internal_pk_bytes[32];
+    secp256k1_xonly_pubkey output_pk;
+    unsigned char output_pk_bytes[32];
+    unsigned char tweak[32];
+    int pk_parity;
+    unsigned char msg[32];
+    unsigned char sig[64];
+
+    /* Create output key */
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_keypair_create(ctx, &keypair, sk) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &internal_pk, NULL, &keypair) == 1);
+    /* In actual taproot the tweak would be hash of internal_pk */
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, tweak, &internal_pk) == 1);
+    CHECK(secp256k1_keypair_xonly_tweak_add(ctx, &keypair, tweak) == 1);
+    CHECK(secp256k1_keypair_xonly_pub(ctx, &output_pk, &pk_parity, &keypair) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, output_pk_bytes, &output_pk) == 1);
+
+    /* Key spend */
+    secp256k1_rand256(msg);
+    CHECK(secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, NULL, NULL) == 1);
+    /* Verify key spend */
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &output_pk, output_pk_bytes) == 1);
+    CHECK(secp256k1_schnorrsig_verify(ctx, sig, msg, &output_pk) == 1);
+
+    /* Script spend */
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, internal_pk_bytes, &internal_pk) == 1);
+    /* Verify script spend */
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &internal_pk, internal_pk_bytes) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add_check(ctx, output_pk_bytes, pk_parity, &internal_pk, tweak) == 1);
+}
+
+void run_schnorrsig_tests(void) {
+    int i;
+    run_nonce_function_bip340_tests();
+
+    test_schnorrsig_api();
+    test_schnorrsig_sha256_tagged();
+    test_schnorrsig_bip_vectors();
+    for (i = 0; i < count; i++) {
+        test_schnorrsig_sign();
+        test_schnorrsig_sign_verify();
+    }
+    test_schnorrsig_taproot();
+}
+
+#endif
diff --git a/src/secp256k1/src/scalar.h b/src/secp256k1/src/scalar.h
index 2a74703523..95d3e326c9 100644
--- a/src/secp256k1/src/scalar.h
+++ b/src/secp256k1/src/scalar.h
@@ -8,6 +8,7 @@
 #define SECP256K1_SCALAR_H
 
 #include "num.h"
+#include "util.h"
 
 #if defined HAVE_CONFIG_H
 #include "libsecp256k1-config.h"
@@ -15,12 +16,12 @@
 
 #if defined(EXHAUSTIVE_TEST_ORDER)
 #include "scalar_low.h"
-#elif defined(USE_SCALAR_4X64)
+#elif defined(SECP256K1_WIDEMUL_INT128)
 #include "scalar_4x64.h"
-#elif defined(USE_SCALAR_8X32)
+#elif defined(SECP256K1_WIDEMUL_INT64)
 #include "scalar_8x32.h"
 #else
-#error "Please select scalar implementation"
+#error "Please select wide multiplication implementation"
 #endif
 
 /** Clear a scalar to prevent the leak of sensitive data. */
diff --git a/src/secp256k1/src/scalar_4x64_impl.h b/src/secp256k1/src/scalar_4x64_impl.h
index 8f539c4bc6..7f39927861 100644
--- a/src/secp256k1/src/scalar_4x64_impl.h
+++ b/src/secp256k1/src/scalar_4x64_impl.h
@@ -192,9 +192,9 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     c0 += tl;                 /* overflow is handled on the next line */ \
-    th += (c0 < tl) ? 1 : 0;  /* at most 0xFFFFFFFFFFFFFFFF */ \
+    th += (c0 < tl);          /* at most 0xFFFFFFFFFFFFFFFF */ \
     c1 += th;                 /* overflow is handled on the next line */ \
-    c2 += (c1 < th) ? 1 : 0;  /* never overflows by contract (verified in the next line) */ \
+    c2 += (c1 < th);          /* never overflows by contract (verified in the next line) */ \
     VERIFY_CHECK((c1 >= th) || (c2 != 0)); \
 }
 
@@ -207,7 +207,7 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     c0 += tl;                 /* overflow is handled on the next line */ \
-    th += (c0 < tl) ? 1 : 0;  /* at most 0xFFFFFFFFFFFFFFFF */ \
+    th += (c0 < tl);          /* at most 0xFFFFFFFFFFFFFFFF */ \
     c1 += th;                 /* never overflows by contract (verified in the next line) */ \
     VERIFY_CHECK(c1 >= th); \
 }
@@ -221,16 +221,16 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     th2 = th + th;                  /* at most 0xFFFFFFFFFFFFFFFE (in case th was 0x7FFFFFFFFFFFFFFF) */ \
-    c2 += (th2 < th) ? 1 : 0;       /* never overflows by contract (verified the next line) */ \
+    c2 += (th2 < th);               /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((th2 >= th) || (c2 != 0)); \
     tl2 = tl + tl;                  /* at most 0xFFFFFFFFFFFFFFFE (in case the lowest 63 bits of tl were 0x7FFFFFFFFFFFFFFF) */ \
-    th2 += (tl2 < tl) ? 1 : 0;      /* at most 0xFFFFFFFFFFFFFFFF */ \
+    th2 += (tl2 < tl);              /* at most 0xFFFFFFFFFFFFFFFF */ \
     c0 += tl2;                      /* overflow is handled on the next line */ \
-    th2 += (c0 < tl2) ? 1 : 0;      /* second overflow is handled on the next line */ \
+    th2 += (c0 < tl2);              /* second overflow is handled on the next line */ \
     c2 += (c0 < tl2) & (th2 == 0);  /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c0 >= tl2) || (th2 != 0) || (c2 != 0)); \
     c1 += th2;                      /* overflow is handled on the next line */ \
-    c2 += (c1 < th2) ? 1 : 0;       /* never overflows by contract (verified the next line) */ \
+    c2 += (c1 < th2);               /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c1 >= th2) || (c2 != 0)); \
 }
 
@@ -238,15 +238,15 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
 #define sumadd(a) { \
     unsigned int over; \
     c0 += (a);                  /* overflow is handled on the next line */ \
-    over = (c0 < (a)) ? 1 : 0; \
+    over = (c0 < (a));         \
     c1 += over;                 /* overflow is handled on the next line */ \
-    c2 += (c1 < over) ? 1 : 0;  /* never overflows by contract */ \
+    c2 += (c1 < over);          /* never overflows by contract */ \
 }
 
 /** Add a to the number defined by (c0,c1). c1 must never overflow, c2 must be zero. */
 #define sumadd_fast(a) { \
     c0 += (a);                 /* overflow is handled on the next line */ \
-    c1 += (c0 < (a)) ? 1 : 0;  /* never overflows by contract (verified the next line) */ \
+    c1 += (c0 < (a));          /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c1 != 0) | (c0 >= (a))); \
     VERIFY_CHECK(c2 == 0); \
 }
diff --git a/src/secp256k1/src/scalar_8x32_impl.h b/src/secp256k1/src/scalar_8x32_impl.h
index 3c372f34fe..f8c7fa7efa 100644
--- a/src/secp256k1/src/scalar_8x32_impl.h
+++ b/src/secp256k1/src/scalar_8x32_impl.h
@@ -271,9 +271,9 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     c0 += tl;                 /* overflow is handled on the next line */ \
-    th += (c0 < tl) ? 1 : 0;  /* at most 0xFFFFFFFF */ \
+    th += (c0 < tl);          /* at most 0xFFFFFFFF */ \
     c1 += th;                 /* overflow is handled on the next line */ \
-    c2 += (c1 < th) ? 1 : 0;  /* never overflows by contract (verified in the next line) */ \
+    c2 += (c1 < th);          /* never overflows by contract (verified in the next line) */ \
     VERIFY_CHECK((c1 >= th) || (c2 != 0)); \
 }
 
@@ -286,7 +286,7 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     c0 += tl;                 /* overflow is handled on the next line */ \
-    th += (c0 < tl) ? 1 : 0;  /* at most 0xFFFFFFFF */ \
+    th += (c0 < tl);          /* at most 0xFFFFFFFF */ \
     c1 += th;                 /* never overflows by contract (verified in the next line) */ \
     VERIFY_CHECK(c1 >= th); \
 }
@@ -300,16 +300,16 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
         tl = t; \
     } \
     th2 = th + th;                  /* at most 0xFFFFFFFE (in case th was 0x7FFFFFFF) */ \
-    c2 += (th2 < th) ? 1 : 0;       /* never overflows by contract (verified the next line) */ \
+    c2 += (th2 < th);               /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((th2 >= th) || (c2 != 0)); \
     tl2 = tl + tl;                  /* at most 0xFFFFFFFE (in case the lowest 63 bits of tl were 0x7FFFFFFF) */ \
-    th2 += (tl2 < tl) ? 1 : 0;      /* at most 0xFFFFFFFF */ \
+    th2 += (tl2 < tl);              /* at most 0xFFFFFFFF */ \
     c0 += tl2;                      /* overflow is handled on the next line */ \
-    th2 += (c0 < tl2) ? 1 : 0;      /* second overflow is handled on the next line */ \
+    th2 += (c0 < tl2);              /* second overflow is handled on the next line */ \
     c2 += (c0 < tl2) & (th2 == 0);  /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c0 >= tl2) || (th2 != 0) || (c2 != 0)); \
     c1 += th2;                      /* overflow is handled on the next line */ \
-    c2 += (c1 < th2) ? 1 : 0;       /* never overflows by contract (verified the next line) */ \
+    c2 += (c1 < th2);               /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c1 >= th2) || (c2 != 0)); \
 }
 
@@ -317,15 +317,15 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
 #define sumadd(a) { \
     unsigned int over; \
     c0 += (a);                  /* overflow is handled on the next line */ \
-    over = (c0 < (a)) ? 1 : 0; \
+    over = (c0 < (a)); \
     c1 += over;                 /* overflow is handled on the next line */ \
-    c2 += (c1 < over) ? 1 : 0;  /* never overflows by contract */ \
+    c2 += (c1 < over);          /* never overflows by contract */ \
 }
 
 /** Add a to the number defined by (c0,c1). c1 must never overflow, c2 must be zero. */
 #define sumadd_fast(a) { \
     c0 += (a);                 /* overflow is handled on the next line */ \
-    c1 += (c0 < (a)) ? 1 : 0;  /* never overflows by contract (verified the next line) */ \
+    c1 += (c0 < (a));          /* never overflows by contract (verified the next line) */ \
     VERIFY_CHECK((c1 != 0) | (c0 >= (a))); \
     VERIFY_CHECK(c2 == 0); \
 }
diff --git a/src/secp256k1/src/scalar_impl.h b/src/secp256k1/src/scalar_impl.h
index 70cd73db06..2ec04b1ae9 100644
--- a/src/secp256k1/src/scalar_impl.h
+++ b/src/secp256k1/src/scalar_impl.h
@@ -16,12 +16,12 @@
 
 #if defined(EXHAUSTIVE_TEST_ORDER)
 #include "scalar_low_impl.h"
-#elif defined(USE_SCALAR_4X64)
+#elif defined(SECP256K1_WIDEMUL_INT128)
 #include "scalar_4x64_impl.h"
-#elif defined(USE_SCALAR_8X32)
+#elif defined(SECP256K1_WIDEMUL_INT64)
 #include "scalar_8x32_impl.h"
 #else
-#error "Please select scalar implementation"
+#error "Please select wide multiplication implementation"
 #endif
 
 static const secp256k1_scalar secp256k1_scalar_one = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 1);
diff --git a/src/secp256k1/src/scratch_impl.h b/src/secp256k1/src/scratch_impl.h
index 4cee700001..b205620224 100644
--- a/src/secp256k1/src/scratch_impl.h
+++ b/src/secp256k1/src/scratch_impl.h
@@ -11,7 +11,7 @@
 #include "scratch.h"
 
 static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t size) {
-    const size_t base_alloc = ((sizeof(secp256k1_scratch) + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
+    const size_t base_alloc = ROUND_TO_ALIGN(sizeof(secp256k1_scratch));
     void *alloc = checked_malloc(error_callback, base_alloc + size);
     secp256k1_scratch* ret = (secp256k1_scratch *)alloc;
     if (ret != NULL) {
@@ -60,6 +60,10 @@ static size_t secp256k1_scratch_max_allocation(const secp256k1_callback* error_c
         secp256k1_callback_call(error_callback, "invalid scratch space");
         return 0;
     }
+    /* Ensure that multiplication will not wrap around */
+    if (ALIGNMENT > 1 && objects > SIZE_MAX/(ALIGNMENT - 1)) {
+        return 0;
+    }
     if (scratch->max_size - scratch->alloc_size <= objects * (ALIGNMENT - 1)) {
         return 0;
     }
@@ -68,7 +72,14 @@ static size_t secp256k1_scratch_max_allocation(const secp256k1_callback* error_c
 
 static void *secp256k1_scratch_alloc(const secp256k1_callback* error_callback, secp256k1_scratch* scratch, size_t size) {
     void *ret;
-    size = ROUND_TO_ALIGN(size);
+    size_t rounded_size;
+
+    rounded_size = ROUND_TO_ALIGN(size);
+    /* Check that rounding did not wrap around */
+    if (rounded_size < size) {
+        return NULL;
+    }
+    size = rounded_size;
 
     if (memcmp(scratch->magic, "scratch", 8) != 0) {
         secp256k1_callback_call(error_callback, "invalid scratch space");
diff --git a/src/secp256k1/src/secp256k1.c b/src/secp256k1/src/secp256k1.c
index b03a6e6345..eaafb3a21d 100644
--- a/src/secp256k1/src/secp256k1.c
+++ b/src/secp256k1/src/secp256k1.c
@@ -7,6 +7,7 @@
 #include "include/secp256k1.h"
 #include "include/secp256k1_preallocated.h"
 
+#include "assumptions.h"
 #include "util.h"
 #include "num_impl.h"
 #include "field_impl.h"
@@ -19,6 +20,7 @@
 #include "eckey_impl.h"
 #include "hash_impl.h"
 #include "scratch_impl.h"
+#include "selftest.h"
 
 #if defined(VALGRIND)
 # include <valgrind/memcheck.h>
@@ -117,6 +119,9 @@ secp256k1_context* secp256k1_context_preallocated_create(void* prealloc, unsigne
     size_t prealloc_size;
     secp256k1_context* ret;
 
+    if (!secp256k1_selftest()) {
+        secp256k1_callback_call(&default_error_callback, "self test failed");
+    }
     VERIFY_CHECK(prealloc != NULL);
     prealloc_size = secp256k1_context_preallocated_size(flags);
     ret = (secp256k1_context*)manual_alloc(&prealloc, sizeof(secp256k1_context), base, prealloc_size);
@@ -226,7 +231,7 @@ void secp256k1_scratch_space_destroy(const secp256k1_context *ctx, secp256k1_scr
  *  of the software. This is setup for use with valgrind but could be substituted with
  *  the appropriate instrumentation for other analysis tools.
  */
-static SECP256K1_INLINE void secp256k1_declassify(const secp256k1_context* ctx, void *p, size_t len) {
+static SECP256K1_INLINE void secp256k1_declassify(const secp256k1_context* ctx, const void *p, size_t len) {
 #if defined(VALGRIND)
     if (EXPECT(ctx->declassify,0)) VALGRIND_MAKE_MEM_DEFINED(p, len);
 #else
@@ -291,7 +296,7 @@ int secp256k1_ec_pubkey_serialize(const secp256k1_context* ctx, unsigned char *o
 
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(outputlen != NULL);
-    ARG_CHECK(*outputlen >= ((flags & SECP256K1_FLAGS_BIT_COMPRESSION) ? 33 : 65));
+    ARG_CHECK(*outputlen >= ((flags & SECP256K1_FLAGS_BIT_COMPRESSION) ? 33u : 65u));
     len = *outputlen;
     *outputlen = 0;
     ARG_CHECK(output != NULL);
@@ -548,10 +553,21 @@ int secp256k1_ec_seckey_verify(const secp256k1_context* ctx, const unsigned char
     return ret;
 }
 
-int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *seckey) {
+static int secp256k1_ec_pubkey_create_helper(const secp256k1_ecmult_gen_context *ecmult_gen_ctx, secp256k1_scalar *seckey_scalar, secp256k1_ge *p, const unsigned char *seckey) {
     secp256k1_gej pj;
+    int ret;
+
+    ret = secp256k1_scalar_set_b32_seckey(seckey_scalar, seckey);
+    secp256k1_scalar_cmov(seckey_scalar, &secp256k1_scalar_one, !ret);
+
+    secp256k1_ecmult_gen(ecmult_gen_ctx, &pj, seckey_scalar);
+    secp256k1_ge_set_gej(p, &pj);
+    return ret;
+}
+
+int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *seckey) {
     secp256k1_ge p;
-    secp256k1_scalar sec;
+    secp256k1_scalar seckey_scalar;
     int ret = 0;
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(pubkey != NULL);
@@ -559,15 +575,11 @@ int secp256k1_ec_pubkey_create(const secp256k1_context* ctx, secp256k1_pubkey *p
     ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
     ARG_CHECK(seckey != NULL);
 
-    ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
-    secp256k1_scalar_cmov(&sec, &secp256k1_scalar_one, !ret);
-
-    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pj, &sec);
-    secp256k1_ge_set_gej(&p, &pj);
+    ret = secp256k1_ec_pubkey_create_helper(&ctx->ecmult_gen_ctx, &seckey_scalar, &p, seckey);
     secp256k1_pubkey_save(pubkey, &p);
     memczero(pubkey, sizeof(*pubkey), !ret);
 
-    secp256k1_scalar_clear(&sec);
+    secp256k1_scalar_clear(&seckey_scalar);
     return ret;
 }
 
@@ -605,24 +617,31 @@ int secp256k1_ec_pubkey_negate(const secp256k1_context* ctx, secp256k1_pubkey *p
     return ret;
 }
 
-int secp256k1_ec_seckey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
+
+static int secp256k1_ec_seckey_tweak_add_helper(secp256k1_scalar *sec, const unsigned char *tweak) {
     secp256k1_scalar term;
+    int overflow = 0;
+    int ret = 0;
+
+    secp256k1_scalar_set_b32(&term, tweak, &overflow);
+    ret = (!overflow) & secp256k1_eckey_privkey_tweak_add(sec, &term);
+    secp256k1_scalar_clear(&term);
+    return ret;
+}
+
+int secp256k1_ec_seckey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey, const unsigned char *tweak) {
     secp256k1_scalar sec;
     int ret = 0;
-    int overflow = 0;
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(seckey != NULL);
     ARG_CHECK(tweak != NULL);
 
-    secp256k1_scalar_set_b32(&term, tweak, &overflow);
     ret = secp256k1_scalar_set_b32_seckey(&sec, seckey);
-
-    ret &= (!overflow) & secp256k1_eckey_privkey_tweak_add(&sec, &term);
+    ret &= secp256k1_ec_seckey_tweak_add_helper(&sec, tweak);
     secp256k1_scalar_cmov(&sec, &secp256k1_scalar_zero, !ret);
     secp256k1_scalar_get_b32(seckey, &sec);
 
     secp256k1_scalar_clear(&sec);
-    secp256k1_scalar_clear(&term);
     return ret;
 }
 
@@ -630,25 +649,26 @@ int secp256k1_ec_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *
     return secp256k1_ec_seckey_tweak_add(ctx, seckey, tweak);
 }
 
+static int secp256k1_ec_pubkey_tweak_add_helper(const secp256k1_ecmult_context* ecmult_ctx, secp256k1_ge *p, const unsigned char *tweak) {
+    secp256k1_scalar term;
+    int overflow = 0;
+    secp256k1_scalar_set_b32(&term, tweak, &overflow);
+    return !overflow && secp256k1_eckey_pubkey_tweak_add(ecmult_ctx, p, &term);
+}
+
 int secp256k1_ec_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const unsigned char *tweak) {
     secp256k1_ge p;
-    secp256k1_scalar term;
     int ret = 0;
-    int overflow = 0;
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
     ARG_CHECK(pubkey != NULL);
     ARG_CHECK(tweak != NULL);
 
-    secp256k1_scalar_set_b32(&term, tweak, &overflow);
-    ret = !overflow && secp256k1_pubkey_load(ctx, &p, pubkey);
+    ret = secp256k1_pubkey_load(ctx, &p, pubkey);
     memset(pubkey, 0, sizeof(*pubkey));
+    ret = ret && secp256k1_ec_pubkey_tweak_add_helper(&ctx->ecmult_ctx, &p, tweak);
     if (ret) {
-        if (secp256k1_eckey_pubkey_tweak_add(&ctx->ecmult_ctx, &p, &term)) {
-            secp256k1_pubkey_save(pubkey, &p);
-        } else {
-            ret = 0;
-        }
+        secp256k1_pubkey_save(pubkey, &p);
     }
 
     return ret;
@@ -741,3 +761,11 @@ int secp256k1_ec_pubkey_combine(const secp256k1_context* ctx, secp256k1_pubkey *
 #ifdef ENABLE_MODULE_RECOVERY
 # include "modules/recovery/main_impl.h"
 #endif
+
+#ifdef ENABLE_MODULE_EXTRAKEYS
+# include "modules/extrakeys/main_impl.h"
+#endif
+
+#ifdef ENABLE_MODULE_SCHNORRSIG
+# include "modules/schnorrsig/main_impl.h"
+#endif
diff --git a/src/secp256k1/src/selftest.h b/src/secp256k1/src/selftest.h
new file mode 100644
index 0000000000..885983aa20
--- /dev/null
+++ b/src/secp256k1/src/selftest.h
@@ -0,0 +1,32 @@
+/**********************************************************************
+ * Copyright (c) 2020 Pieter Wuille                                   *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef SECP256K1_SELFTEST_H
+#define SECP256K1_SELFTEST_H
+
+#include "hash.h"
+
+#include <string.h>
+
+static int secp256k1_selftest_sha256(void) {
+    static const char *input63 = "For this sample, this 63-byte string will be used as input data";
+    static const unsigned char output32[32] = {
+        0xf0, 0x8a, 0x78, 0xcb, 0xba, 0xee, 0x08, 0x2b, 0x05, 0x2a, 0xe0, 0x70, 0x8f, 0x32, 0xfa, 0x1e,
+        0x50, 0xc5, 0xc4, 0x21, 0xaa, 0x77, 0x2b, 0xa5, 0xdb, 0xb4, 0x06, 0xa2, 0xea, 0x6b, 0xe3, 0x42,
+    };
+    unsigned char out[32];
+    secp256k1_sha256 hasher;
+    secp256k1_sha256_initialize(&hasher);
+    secp256k1_sha256_write(&hasher, (const unsigned char*)input63, 63);
+    secp256k1_sha256_finalize(&hasher, out);
+    return memcmp(out, output32, 32) == 0;
+}
+
+static int secp256k1_selftest(void) {
+    return secp256k1_selftest_sha256();
+}
+
+#endif /* SECP256K1_SELFTEST_H */
diff --git a/src/secp256k1/src/testrand.h b/src/secp256k1/src/testrand.h
index f1f9be077e..bcbe15a6f1 100644
--- a/src/secp256k1/src/testrand.h
+++ b/src/secp256k1/src/testrand.h
@@ -35,4 +35,7 @@ static void secp256k1_rand256_test(unsigned char *b32);
 /** Generate pseudorandom bytes with long sequences of zero and one bits. */
 static void secp256k1_rand_bytes_test(unsigned char *bytes, size_t len);
 
+/** Flip a single random bit in a byte array */
+static void secp256k1_rand_flip(unsigned char *b, size_t len);
+
 #endif /* SECP256K1_TESTRAND_H */
diff --git a/src/secp256k1/src/testrand_impl.h b/src/secp256k1/src/testrand_impl.h
index 30a91e5296..dfb658d9c6 100644
--- a/src/secp256k1/src/testrand_impl.h
+++ b/src/secp256k1/src/testrand_impl.h
@@ -107,4 +107,8 @@ static void secp256k1_rand256_test(unsigned char *b32) {
     secp256k1_rand_bytes_test(b32, 32);
 }
 
+static void secp256k1_rand_flip(unsigned char *b, size_t len) {
+    b[secp256k1_rand_int(len)] ^= (1 << secp256k1_rand_int(8));
+}
+
 #endif /* SECP256K1_TESTRAND_IMPL_H */
diff --git a/src/secp256k1/src/tests.c b/src/secp256k1/src/tests.c
index 374ed7dc12..4780e9319b 100644
--- a/src/secp256k1/src/tests.c
+++ b/src/secp256k1/src/tests.c
@@ -182,8 +182,10 @@ void run_context_tests(int use_prealloc) {
     ecount2 = 10;
     secp256k1_context_set_illegal_callback(vrfy, counting_illegal_callback_fn, &ecount);
     secp256k1_context_set_illegal_callback(sign, counting_illegal_callback_fn, &ecount2);
-    secp256k1_context_set_error_callback(sign, counting_illegal_callback_fn, NULL);
-    CHECK(vrfy->error_callback.fn != sign->error_callback.fn);
+    /* set error callback (to a function that still aborts in case malloc() fails in secp256k1_context_clone() below) */
+    secp256k1_context_set_error_callback(sign, secp256k1_default_illegal_callback_fn, NULL);
+    CHECK(sign->error_callback.fn != vrfy->error_callback.fn);
+    CHECK(sign->error_callback.fn == secp256k1_default_illegal_callback_fn);
 
     /* check if sizes for cloning are consistent */
     CHECK(secp256k1_context_preallocated_clone_size(none) == secp256k1_context_preallocated_size(SECP256K1_CONTEXT_NONE));
@@ -239,7 +241,8 @@ void run_context_tests(int use_prealloc) {
     }
 
     /* Verify that the error callback makes it across the clone. */
-    CHECK(vrfy->error_callback.fn != sign->error_callback.fn);
+    CHECK(sign->error_callback.fn != vrfy->error_callback.fn);
+    CHECK(sign->error_callback.fn == secp256k1_default_illegal_callback_fn);
     /* And that it resets back to default. */
     secp256k1_context_set_error_callback(sign, NULL, NULL);
     CHECK(vrfy->error_callback.fn == sign->error_callback.fn);
@@ -361,8 +364,8 @@ void run_scratch_tests(void) {
     CHECK(scratch->alloc_size != 0);
     CHECK(scratch->alloc_size % ALIGNMENT == 0);
 
-    /* Allocating another 500 bytes fails */
-    CHECK(secp256k1_scratch_alloc(&none->error_callback, scratch, 500) == NULL);
+    /* Allocating another 501 bytes fails */
+    CHECK(secp256k1_scratch_alloc(&none->error_callback, scratch, 501) == NULL);
     CHECK(secp256k1_scratch_max_allocation(&none->error_callback, scratch, 0) == 1000 - adj_alloc);
     CHECK(secp256k1_scratch_max_allocation(&none->error_callback, scratch, 1) == 1000 - adj_alloc - (ALIGNMENT - 1));
     CHECK(scratch->alloc_size != 0);
@@ -395,6 +398,18 @@ void run_scratch_tests(void) {
     secp256k1_scratch_space_destroy(none, scratch);
     CHECK(ecount == 5);
 
+    /* Test that large integers do not wrap around in a bad way */
+    scratch = secp256k1_scratch_space_create(none, 1000);
+    /* Try max allocation with a large number of objects. Only makes sense if
+     * ALIGNMENT is greater than 1 because otherwise the objects take no extra
+     * space. */
+    CHECK(ALIGNMENT <= 1 || !secp256k1_scratch_max_allocation(&none->error_callback, scratch, (SIZE_MAX / (ALIGNMENT - 1)) + 1));
+    /* Try allocating SIZE_MAX to test wrap around which only happens if
+     * ALIGNMENT > 1, otherwise it returns NULL anyway because the scratch
+     * space is too small. */
+    CHECK(secp256k1_scratch_alloc(&none->error_callback, scratch, SIZE_MAX) == NULL);
+    secp256k1_scratch_space_destroy(none, scratch);
+
     /* cleanup */
     secp256k1_scratch_space_destroy(none, NULL); /* no-op */
     secp256k1_context_destroy(none);
@@ -2215,6 +2230,9 @@ void test_ge(void) {
                 /* Normal doubling. */
                 secp256k1_gej_double_var(&resj, &gej[i2], NULL);
                 ge_equals_gej(&ref, &resj);
+                /* Constant-time doubling. */
+                secp256k1_gej_double(&resj, &gej[i2]);
+                ge_equals_gej(&ref, &resj);
             }
 
             /* Test adding opposites. */
@@ -2300,6 +2318,39 @@ void test_ge(void) {
     free(zinv);
 }
 
+
+void test_intialized_inf(void) {
+    secp256k1_ge p;
+    secp256k1_gej pj, npj, infj1, infj2, infj3;
+    secp256k1_fe zinv;
+
+    /* Test that adding P+(-P) results in a fully initalized infinity*/
+    random_group_element_test(&p);
+    secp256k1_gej_set_ge(&pj, &p);
+    secp256k1_gej_neg(&npj, &pj);
+
+    secp256k1_gej_add_var(&infj1, &pj, &npj, NULL);
+    CHECK(secp256k1_gej_is_infinity(&infj1));
+    CHECK(secp256k1_fe_is_zero(&infj1.x));
+    CHECK(secp256k1_fe_is_zero(&infj1.y));
+    CHECK(secp256k1_fe_is_zero(&infj1.z));
+
+    secp256k1_gej_add_ge_var(&infj2, &npj, &p, NULL);
+    CHECK(secp256k1_gej_is_infinity(&infj2));
+    CHECK(secp256k1_fe_is_zero(&infj2.x));
+    CHECK(secp256k1_fe_is_zero(&infj2.y));
+    CHECK(secp256k1_fe_is_zero(&infj2.z));
+
+    secp256k1_fe_set_int(&zinv, 1);
+    secp256k1_gej_add_zinv_var(&infj3, &npj, &p, &zinv);
+    CHECK(secp256k1_gej_is_infinity(&infj3));
+    CHECK(secp256k1_fe_is_zero(&infj3.x));
+    CHECK(secp256k1_fe_is_zero(&infj3.y));
+    CHECK(secp256k1_fe_is_zero(&infj3.z));
+
+
+}
+
 void test_add_neg_y_diff_x(void) {
     /* The point of this test is to check that we can add two points
      * whose y-coordinates are negatives of each other but whose x
@@ -2373,6 +2424,7 @@ void run_ge(void) {
         test_ge();
     }
     test_add_neg_y_diff_x();
+    test_intialized_inf();
 }
 
 void test_ec_combine(void) {
@@ -2967,14 +3019,16 @@ void test_ecmult_multi(secp256k1_scratch *scratch, secp256k1_ecmult_multi_func e
 
 void test_ecmult_multi_batch_single(secp256k1_ecmult_multi_func ecmult_multi) {
     secp256k1_scalar szero;
-    secp256k1_scalar sc[32];
-    secp256k1_ge pt[32];
+    secp256k1_scalar sc;
+    secp256k1_ge pt;
     secp256k1_gej r;
     ecmult_multi_data data;
     secp256k1_scratch *scratch_empty;
 
-    data.sc = sc;
-    data.pt = pt;
+    random_group_element_test(&pt);
+    random_scalar_order(&sc);
+    data.sc = &sc;
+    data.pt = &pt;
     secp256k1_scalar_set_int(&szero, 0);
 
     /* Try to multiply 1 point, but scratch space is empty.*/
@@ -3232,6 +3286,7 @@ void test_constant_wnaf(const secp256k1_scalar *number, int w) {
     int skew;
     int bits = 256;
     secp256k1_scalar num = *number;
+    secp256k1_scalar scalar_skew;
 
     secp256k1_scalar_set_int(&x, 0);
     secp256k1_scalar_set_int(&shift, 1 << w);
@@ -3262,7 +3317,8 @@ void test_constant_wnaf(const secp256k1_scalar *number, int w) {
         secp256k1_scalar_add(&x, &x, &t);
     }
     /* Skew num because when encoding numbers as odd we use an offset */
-    secp256k1_scalar_cadd_bit(&num, skew == 2, 1);
+    secp256k1_scalar_set_int(&scalar_skew, 1 << (skew == 2));
+    secp256k1_scalar_add(&num, &num, &scalar_skew);
     CHECK(secp256k1_scalar_eq(&x, &num));
 }
 
@@ -3374,13 +3430,32 @@ void run_wnaf(void) {
     int i;
     secp256k1_scalar n = {{0}};
 
+    test_constant_wnaf(&n, 4);
     /* Sanity check: 1 and 2 are the smallest odd and even numbers and should
      *               have easier-to-diagnose failure modes  */
     n.d[0] = 1;
     test_constant_wnaf(&n, 4);
     n.d[0] = 2;
     test_constant_wnaf(&n, 4);
-    /* Test 0 */
+    /* Test -1, because it's a special case in wnaf_const */
+    n = secp256k1_scalar_one;
+    secp256k1_scalar_negate(&n, &n);
+    test_constant_wnaf(&n, 4);
+
+    /* Test -2, which may not lead to overflows in wnaf_const */
+    secp256k1_scalar_add(&n, &secp256k1_scalar_one, &secp256k1_scalar_one);
+    secp256k1_scalar_negate(&n, &n);
+    test_constant_wnaf(&n, 4);
+
+    /* Test (1/2) - 1 = 1/-2 and 1/2 = (1/-2) + 1
+       as corner cases of negation handling in wnaf_const */
+    secp256k1_scalar_inverse(&n, &n);
+    test_constant_wnaf(&n, 4);
+
+    secp256k1_scalar_add(&n, &n, &secp256k1_scalar_one);
+    test_constant_wnaf(&n, 4);
+
+    /* Test 0 for fixed wnaf */
     test_fixed_wnaf_small();
     /* Random tests */
     for (i = 0; i < count; i++) {
@@ -5277,6 +5352,14 @@ void run_ecdsa_openssl(void) {
 # include "modules/recovery/tests_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_EXTRAKEYS
+# include "modules/extrakeys/tests_impl.h"
+#endif
+
+#ifdef ENABLE_MODULE_SCHNORRSIG
+# include "modules/schnorrsig/tests_impl.h"
+#endif
+
 void run_memczero_test(void) {
     unsigned char buf1[6] = {1, 2, 3, 4, 5, 6};
     unsigned char buf2[sizeof(buf1)];
@@ -5583,6 +5666,14 @@ int main(int argc, char **argv) {
     run_recovery_tests();
 #endif
 
+#ifdef ENABLE_MODULE_EXTRAKEYS
+    run_extrakeys_tests();
+#endif
+
+#ifdef ENABLE_MODULE_SCHNORRSIG
+    run_schnorrsig_tests();
+#endif
+
     /* util tests */
     run_memczero_test();
 
diff --git a/src/secp256k1/src/tests_exhaustive.c b/src/secp256k1/src/tests_exhaustive.c
index 8cca1cef21..681ed80bd0 100644
--- a/src/secp256k1/src/tests_exhaustive.c
+++ b/src/secp256k1/src/tests_exhaustive.c
@@ -22,6 +22,7 @@
 #endif
 
 #include "include/secp256k1.h"
+#include "assumptions.h"
 #include "group.h"
 #include "secp256k1.c"
 #include "testrand_impl.h"
@@ -141,10 +142,8 @@ void test_exhaustive_addition(const secp256k1_ge *group, const secp256k1_gej *gr
     /* Check doubling */
     for (i = 0; i < order; i++) {
         secp256k1_gej tmp;
-        if (i > 0) {
-            secp256k1_gej_double_nonzero(&tmp, &groupj[i]);
-            ge_equals_gej(&group[(2 * i) % order], &tmp);
-        }
+        secp256k1_gej_double(&tmp, &groupj[i]);
+        ge_equals_gej(&group[(2 * i) % order], &tmp);
         secp256k1_gej_double_var(&tmp, &groupj[i], NULL);
         ge_equals_gej(&group[(2 * i) % order], &tmp);
     }
diff --git a/src/secp256k1/src/util.h b/src/secp256k1/src/util.h
index 8289e23e0c..a5cbe03ef5 100644
--- a/src/secp256k1/src/util.h
+++ b/src/secp256k1/src/util.h
@@ -170,13 +170,35 @@ static SECP256K1_INLINE void *manual_alloc(void** prealloc_ptr, size_t alloc_siz
 # define I64uFORMAT "llu"
 #endif
 
-#if defined(HAVE___INT128)
-# if defined(__GNUC__)
-#  define SECP256K1_GNUC_EXT __extension__
-# else
-#  define SECP256K1_GNUC_EXT
+#if defined(__GNUC__)
+# define SECP256K1_GNUC_EXT __extension__
+#else
+# define SECP256K1_GNUC_EXT
+#endif
+
+/* If SECP256K1_{LITTLE,BIG}_ENDIAN is not explicitly provided, infer from various other system macros. */
+#if !defined(SECP256K1_LITTLE_ENDIAN) && !defined(SECP256K1_BIG_ENDIAN)
+/* Inspired by https://github.com/rofl0r/endianness.h/blob/9853923246b065a3b52d2c43835f3819a62c7199/endianness.h#L52L73 */
+# if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) || \
+     defined(_X86_) || defined(__x86_64__) || defined(__i386__) || \
+     defined(__i486__) || defined(__i586__) || defined(__i686__) || \
+     defined(__MIPSEL) || defined(_MIPSEL) || defined(MIPSEL) || \
+     defined(__ARMEL__) || defined(__AARCH64EL__) || \
+     (defined(__LITTLE_ENDIAN__) && __LITTLE_ENDIAN__ == 1) || \
+     (defined(_LITTLE_ENDIAN) && _LITTLE_ENDIAN == 1) || \
+     defined(_M_IX86) || defined(_M_AMD64) || defined(_M_ARM) /* MSVC */
+#  define SECP256K1_LITTLE_ENDIAN
 # endif
-SECP256K1_GNUC_EXT typedef unsigned __int128 uint128_t;
+# if (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) || \
+     defined(__MIPSEB) || defined(_MIPSEB) || defined(MIPSEB) || \
+     defined(__MICROBLAZEEB__) || defined(__ARMEB__) || defined(__AARCH64EB__) || \
+     (defined(__BIG_ENDIAN__) && __BIG_ENDIAN__ == 1) || \
+     (defined(_BIG_ENDIAN) && _BIG_ENDIAN == 1)
+#  define SECP256K1_BIG_ENDIAN
+# endif
+#endif
+#if defined(SECP256K1_LITTLE_ENDIAN) == defined(SECP256K1_BIG_ENDIAN)
+# error Please make sure that either SECP256K1_LITTLE_ENDIAN or SECP256K1_BIG_ENDIAN is set, see src/util.h.
 #endif
 
 /* Zero memory if flag == 1. Flag must be 0 or 1. Constant time. */
@@ -197,10 +219,15 @@ static SECP256K1_INLINE void memczero(void *s, size_t len, int flag) {
 /** If flag is true, set *r equal to *a; otherwise leave it. Constant-time.  Both *r and *a must be initialized and non-negative.*/
 static SECP256K1_INLINE void secp256k1_int_cmov(int *r, const int *a, int flag) {
     unsigned int mask0, mask1, r_masked, a_masked;
+    /* Access flag with a volatile-qualified lvalue.
+       This prevents clang from figuring out (after inlining) that flag can
+       take only be 0 or 1, which leads to variable time code. */
+    volatile int vflag = flag;
+
     /* Casting a negative int to unsigned and back to int is implementation defined behavior */
     VERIFY_CHECK(*r >= 0 && *a >= 0);
 
-    mask0 = (unsigned int)flag + ~0u;
+    mask0 = (unsigned int)vflag + ~0u;
     mask1 = ~mask0;
     r_masked = ((unsigned int)*r & mask0);
     a_masked = ((unsigned int)*a & mask1);
@@ -208,4 +235,21 @@ static SECP256K1_INLINE void secp256k1_int_cmov(int *r, const int *a, int flag)
     *r = (int)(r_masked | a_masked);
 }
 
+/* If USE_FORCE_WIDEMUL_{INT128,INT64} is set, use that wide multiplication implementation.
+ * Otherwise use the presence of __SIZEOF_INT128__ to decide.
+ */
+#if defined(USE_FORCE_WIDEMUL_INT128)
+# define SECP256K1_WIDEMUL_INT128 1
+#elif defined(USE_FORCE_WIDEMUL_INT64)
+# define SECP256K1_WIDEMUL_INT64 1
+#elif defined(__SIZEOF_INT128__)
+# define SECP256K1_WIDEMUL_INT128 1
+#else
+# define SECP256K1_WIDEMUL_INT64 1
+#endif
+#if defined(SECP256K1_WIDEMUL_INT128)
+SECP256K1_GNUC_EXT typedef unsigned __int128 uint128_t;
+SECP256K1_GNUC_EXT typedef __int128 int128_t;
+#endif
+
 #endif /* SECP256K1_UTIL_H */
diff --git a/src/secp256k1/src/valgrind_ctime_test.c b/src/secp256k1/src/valgrind_ctime_test.c
index 60a82d599e..e676a8326c 100644
--- a/src/secp256k1/src/valgrind_ctime_test.c
+++ b/src/secp256k1/src/valgrind_ctime_test.c
@@ -6,6 +6,7 @@
 
 #include <valgrind/memcheck.h>
 #include "include/secp256k1.h"
+#include "assumptions.h"
 #include "util.h"
 
 #if ENABLE_MODULE_ECDH
@@ -16,6 +17,14 @@
 # include "include/secp256k1_recovery.h"
 #endif
 
+#if ENABLE_MODULE_EXTRAKEYS
+# include "include/secp256k1_extrakeys.h"
+#endif
+
+#if ENABLE_MODULE_SCHNORRSIG
+#include "include/secp256k1_schnorrsig.h"
+#endif
+
 int main(void) {
     secp256k1_context* ctx;
     secp256k1_ecdsa_signature signature;
@@ -32,6 +41,9 @@ int main(void) {
     secp256k1_ecdsa_recoverable_signature recoverable_signature;
     int recid;
 #endif
+#if ENABLE_MODULE_EXTRAKEYS
+    secp256k1_keypair keypair;
+#endif
 
     if (!RUNNING_ON_VALGRIND) {
         fprintf(stderr, "This test can only usefully be run inside valgrind.\n");
@@ -49,7 +61,9 @@ int main(void) {
         msg[i] = i + 1;
     }
 
-    ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_DECLASSIFY);
+    ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN
+                                   | SECP256K1_CONTEXT_VERIFY
+                                   | SECP256K1_CONTEXT_DECLASSIFY);
 
     /* Test keygen. */
     VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
@@ -114,6 +128,30 @@ int main(void) {
     VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
     CHECK(ret);
 
+    /* Test keypair_create and keypair_xonly_tweak_add. */
+#if ENABLE_MODULE_EXTRAKEYS
+    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    ret = secp256k1_keypair_create(ctx, &keypair, key);
+    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    CHECK(ret == 1);
+
+    /* The tweak is not treated as a secret in keypair_tweak_add */
+    VALGRIND_MAKE_MEM_DEFINED(msg, 32);
+    ret = secp256k1_keypair_xonly_tweak_add(ctx, &keypair, msg);
+    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    CHECK(ret == 1);
+#endif
+
+#if ENABLE_MODULE_SCHNORRSIG
+    VALGRIND_MAKE_MEM_UNDEFINED(key, 32);
+    ret = secp256k1_keypair_create(ctx, &keypair, key);
+    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    CHECK(ret == 1);
+    ret = secp256k1_schnorrsig_sign(ctx, sig, msg, &keypair, NULL, NULL);
+    VALGRIND_MAKE_MEM_DEFINED(&ret, sizeof(ret));
+    CHECK(ret == 1);
+#endif
+
     secp256k1_context_destroy(ctx);
     return 0;
 }