Squashed 'src/secp256k1/' changes from 1897b8e..22f60a6

22f60a6 Merge pull request #245
61c1b1e Merge pull request #190
d227579 Add scalar blinding and a secp256k1_context_randomize() call.
c146b4a Add bench_internal to gitignore.
9c4fb23 Add a secp256k1_fe_cmov unit test.
426fa52 Merge pull request #243
d505a89 Merge pull request #244
2d2707a travis: test i686 builds with gmp
cf7f702 travis: update to new build infrastructure
bb0ea50 Replace set/add with cmov in secp256k1_gej_add_ge.
f3d3519 Merge pull request #241
5c2a4fa Fix memory leak in context unit test
14aacdc Merge pull request #239
93226a5 secp256k1.c: Add missing DEBUG_CHECKs for sufficiently capable contexts
6099220 Merge pull request #237
6066bb6 Fix typo: avg -> max
9688030 Merge pull request #236
d899b5b Expose ability to deep-copy a context
3608c7f Merge pull request #208
a9b6595 [API BREAK] Introduce explicit contexts
a0d3b89 Merge pull request #233
9e8d89b Merge pull request #234
65e70e7 Merge pull request #235
5098f62 Improve documentation formatting consistency
4450e24 Add a comment about the avoidance of secret data in array indexes.
6534ee1 initialize variable
d5b53aa Merge pull request #232
c01df1a Avoid some implicit type conversions to make C++ compilers happy.
bfe96ba Merge pull request #231
33270bf Add a couple comments pointing to particular sections of RFC6979.
41603aa Merge pull request #230
2632019 Brace all the if/for/while.

git-subtree-dir: src/secp256k1
git-subtree-split: 22f60a62801a8a49ecd049e7a563f69a41affd8d

1 files changed, 101 insertions, 49 deletions

diff --git a/include/secp256k1.h b/include/secp256k1.h
index a6e39d13db..06afd4c65b 100644
--- a/include/secp256k1.h
+++ b/include/secp256k1.h
@@ -40,42 +40,60 @@ extern "C" {
 #  define SECP256K1_ARG_NONNULL(_x)
 # endif
 
+/** Opaque data structure that holds context information (precomputed tables etc.).
+ *  Only functions that take a pointer to a non-const context require exclusive
+ *  access to it. Multiple functions that take a pointer to a const context may
+ *  run simultaneously.
+ */
+typedef struct secp256k1_context_struct secp256k1_context_t;
+
+/** Flags to pass to secp256k1_context_create. */
+# define SECP256K1_CONTEXT_VERIFY (1 << 0)
+# define SECP256K1_CONTEXT_SIGN   (1 << 1)
 
-/** Flags to pass to secp256k1_start. */
-# define SECP256K1_START_VERIFY (1 << 0)
-# define SECP256K1_START_SIGN   (1 << 1)
+/** Create a secp256k1 context object.
+ *  Returns: a newly created context object.
+ *  In:      flags: which parts of the context to initialize.
+ */
+secp256k1_context_t* secp256k1_context_create(
+  int flags
+) SECP256K1_WARN_UNUSED_RESULT;
 
-/** Initialize the library. This may take some time (10-100 ms).
- *  You need to call this before calling any other function.
- *  It cannot run in parallel with any other functions, but once
- *  secp256k1_start() returns, all other functions are thread-safe.
+/** Copies a secp256k1 context object.
+ *  Returns: a newly created context object.
+ *  In:      ctx: an existing context to copy
  */
-void secp256k1_start(unsigned int flags);
+secp256k1_context_t* secp256k1_context_clone(
+  const secp256k1_context_t* ctx
+) SECP256K1_WARN_UNUSED_RESULT;
 
-/** Free all memory associated with this library. After this, no
- *  functions can be called anymore, except secp256k1_start()
+/** Destroy a secp256k1 context object.
+ *  The context pointer may not be used afterwards.
  */
-void secp256k1_stop(void);
+void secp256k1_context_destroy(
+  secp256k1_context_t* ctx
+) SECP256K1_ARG_NONNULL(1);
 
 /** Verify an ECDSA signature.
  *  Returns: 1: correct signature
  *           0: incorrect signature
  *          -1: invalid public key
  *          -2: invalid signature
- * In:       msg32:     the 32-byte message hash being verified (cannot be NULL)
+ * In:       ctx:       a secp256k1 context object, initialized for verification.
+ *           msg32:     the 32-byte message hash being verified (cannot be NULL)
  *           sig:       the signature being verified (cannot be NULL)
  *           siglen:    the length of the signature
  *           pubkey:    the public key to verify with (cannot be NULL)
  *           pubkeylen: the length of pubkey
- * Requires starting using SECP256K1_START_VERIFY.
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
+  const secp256k1_context_t* ctx,
   const unsigned char *msg32,
   const unsigned char *sig,
   int siglen,
   const unsigned char *pubkey,
   int pubkeylen
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5);
 
 /** A pointer to a function to deterministically generate a nonce.
  * Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail.
@@ -111,15 +129,14 @@ extern const secp256k1_nonce_function_t secp256k1_nonce_function_default;
  *  Returns: 1: signature created
  *           0: the nonce generation function failed, the private key was invalid, or there is not
  *              enough space in the signature (as indicated by siglen).
- *  In:      msg32:  the 32-byte message hash being signed (cannot be NULL)
+ *  In:      ctx:    pointer to a context object, initialized for signing (cannot be NULL)
+ *           msg32:  the 32-byte message hash being signed (cannot be NULL)
  *           seckey: pointer to a 32-byte secret key (cannot be NULL)
  *           noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
  *           ndata:  pointer to arbitrary data used by the nonce generation function (can be NULL)
  *  Out:     sig:    pointer to an array where the signature will be placed (cannot be NULL)
  *  In/Out:  siglen: pointer to an int with the length of sig, which will be updated
- *                   to contain the actual signature length (<=72). If 0 is returned, this will be
- *                   set to zero.
- * Requires starting using SECP256K1_START_SIGN.
+ *                   to contain the actual signature length (<=72).
  *
  * The sig always has an s value in the lower half of the range (From 0x1
  * to 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
@@ -148,145 +165,180 @@ extern const secp256k1_nonce_function_t secp256k1_nonce_function_default;
  * be taken when this property is required for an application.
  */
 int secp256k1_ecdsa_sign(
+  const secp256k1_context_t* ctx,
   const unsigned char *msg32,
   unsigned char *sig,
   int *siglen,
   const unsigned char *seckey,
   secp256k1_nonce_function_t noncefp,
   const void *ndata
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
 
 /** Create a compact ECDSA signature (64 byte + recovery id).
  *  Returns: 1: signature created
  *           0: the nonce generation function failed, or the secret key was invalid.
- *  In:      msg32:  the 32-byte message hash being signed (cannot be NULL)
+ *  In:      ctx:    pointer to a context object, initialized for signing (cannot be NULL)
+ *           msg32:  the 32-byte message hash being signed (cannot be NULL)
  *           seckey: pointer to a 32-byte secret key (cannot be NULL)
  *           noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
  *           ndata:  pointer to arbitrary data used by the nonce generation function (can be NULL)
  *  Out:     sig:    pointer to a 64-byte array where the signature will be placed (cannot be NULL)
  *                   In case 0 is returned, the returned signature length will be zero.
  *           recid:  pointer to an int, which will be updated to contain the recovery id (can be NULL)
- * Requires starting using SECP256K1_START_SIGN.
  */
 int secp256k1_ecdsa_sign_compact(
+  const secp256k1_context_t* ctx,
   const unsigned char *msg32,
   unsigned char *sig64,
   const unsigned char *seckey,
   secp256k1_nonce_function_t noncefp,
   const void *ndata,
   int *recid
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Recover an ECDSA public key from a compact signature.
  *  Returns: 1: public key successfully recovered (which guarantees a correct signature).
  *           0: otherwise.
- *  In:      msg32:      the 32-byte message hash assumed to be signed (cannot be NULL)
+ *  In:      ctx:        pointer to a context object, initialized for verification (cannot be NULL)
+ *           msg32:      the 32-byte message hash assumed to be signed (cannot be NULL)
  *           sig64:      signature as 64 byte array (cannot be NULL)
  *           compressed: whether to recover a compressed or uncompressed pubkey
  *           recid:      the recovery id (0-3, as returned by ecdsa_sign_compact)
  *  Out:     pubkey:     pointer to a 33 or 65 byte array to put the pubkey (cannot be NULL)
  *           pubkeylen:  pointer to an int that will contain the pubkey length (cannot be NULL)
- * Requires starting using SECP256K1_START_VERIFY.
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover_compact(
+  const secp256k1_context_t* ctx,
   const unsigned char *msg32,
   const unsigned char *sig64,
   unsigned char *pubkey,
   int *pubkeylen,
   int compressed,
   int recid
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
 
 /** Verify an ECDSA secret key.
  *  Returns: 1: secret key is valid
  *           0: secret key is invalid
- *  In:      seckey: pointer to a 32-byte secret key (cannot be NULL)
+ *  In:      ctx: pointer to a context object (cannot be NULL)
+ *           seckey: pointer to a 32-byte secret key (cannot be NULL)
  */
-SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(const unsigned char *seckey) SECP256K1_ARG_NONNULL(1);
+SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(
+  const secp256k1_context_t* ctx,
+  const unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
 
 /** Just validate a public key.
- *  Returns: 1: valid public key
- *           0: invalid public key
- *  In:      pubkey:    pointer to a 33-byte or 65-byte public key (cannot be NULL).
+ *  Returns: 1: public key is valid
+ *           0: public key is invalid
+ *  In:      ctx:       pointer to a context object (cannot be NULL)
+ *           pubkey:    pointer to a 33-byte or 65-byte public key (cannot be NULL).
  *           pubkeylen: length of pubkey
  */
-SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_verify(const unsigned char *pubkey, int pubkeylen) SECP256K1_ARG_NONNULL(1);
+SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_verify(
+  const secp256k1_context_t* ctx,
+  const unsigned char *pubkey,
+  int pubkeylen
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
 
 /** Compute the public key for a secret key.
- *  In:     compressed: whether the computed public key should be compressed
+ *  In:     ctx:        pointer to a context object, initialized for signing (cannot be NULL)
+ *          compressed: whether the computed public key should be compressed
  *          seckey:     pointer to a 32-byte private key (cannot be NULL)
  *  Out:    pubkey:     pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
  *                      area to store the public key (cannot be NULL)
  *          pubkeylen:  pointer to int that will be updated to contains the pubkey's
  *                      length (cannot be NULL)
  *  Returns: 1: secret was valid, public key stores
- *           0: secret was invalid, try again.
- * Requires starting using SECP256K1_START_SIGN.
+ *           0: secret was invalid, try again
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
+  const secp256k1_context_t* ctx,
   unsigned char *pubkey,
   int *pubkeylen,
   const unsigned char *seckey,
   int compressed
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Decompress a public key.
+ * In:     ctx:       pointer to a context object (cannot be NULL)
  * In/Out: pubkey:    pointer to a 65-byte array to put the decompressed public key.
-                      It must contain a 33-byte or 65-byte public key already (cannot be NULL)
+ *                    It must contain a 33-byte or 65-byte public key already (cannot be NULL)
  *         pubkeylen: pointer to the size of the public key pointed to by pubkey (cannot be NULL)
-                      It will be updated to reflect the new size.
- * Returns: 0 if the passed public key was invalid, 1 otherwise. If 1 is returned, the
-            pubkey is replaced with its decompressed version.
+ *                    It will be updated to reflect the new size.
+ * Returns: 0: pubkey was invalid
+ *          1: pubkey was valid, and was replaced with its decompressed version
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_decompress(
+  const secp256k1_context_t* ctx,
   unsigned char *pubkey,
   int *pubkeylen
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
-/** Export a private key in DER format. */
+/** Export a private key in DER format.
+ * In: ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export(
+  const secp256k1_context_t* ctx,
   const unsigned char *seckey,
   unsigned char *privkey,
   int *privkeylen,
   int compressed
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Import a private key in DER format. */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import(
+  const secp256k1_context_t* ctx,
   unsigned char *seckey,
   const unsigned char *privkey,
   int privkeylen
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Tweak a private key by adding tweak to it. */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
+  const secp256k1_context_t* ctx,
   unsigned char *seckey,
   const unsigned char *tweak
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Tweak a public key by adding tweak times the generator to it.
- * Requires starting with SECP256K1_START_VERIFY.
+ * In: ctx: pointer to a context object, initialized for verification (cannot be NULL)
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
+  const secp256k1_context_t* ctx,
   unsigned char *pubkey,
   int pubkeylen,
   const unsigned char *tweak
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
 
 /** Tweak a private key by multiplying it with tweak. */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
+  const secp256k1_context_t* ctx,
   unsigned char *seckey,
   const unsigned char *tweak
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
 /** Tweak a public key by multiplying it with tweak.
- * Requires starting with SECP256K1_START_VERIFY.
+ * In: ctx: pointer to a context object, initialized for verification (cannot be NULL)
  */
 SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
+  const secp256k1_context_t* ctx,
   unsigned char *pubkey,
   int pubkeylen,
   const unsigned char *tweak
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
+
+/** Updates the context randomization.
+ *  Returns: 1: randomization successfully updated
+ *           0: error
+ *  In:      ctx:       pointer to a context object (cannot be NULL)
+ *           seed32:    pointer to a 32-byte random seed (NULL resets to initial state)
+ */
+SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
+  secp256k1_context_t* ctx,
+  const unsigned char *seed32
+) SECP256K1_ARG_NONNULL(1);
+
 
 # ifdef __cplusplus
 }