Squashed 'src/secp256k1/' changes from 50cc6ab..1897b8e

1897b8e Merge pull request #229
efc571c Add simple testcases for signing with rfc6979 extra entropy.
1573a10 Add ability to pass extra entropy to rfc6979
3087bc4 Merge pull request #228
d9b9f11 Merge pull request #218
0065a8f Eliminate multiple-returns from secp256k1.c.
354ffa3 Make secp256k1_ec_pubkey_create reject oversized secrets.
27bc131 Silence some warnings from pedantic static analysis tools, improve compatibility with C++.
3b7ea63 Merge pull request #221
f789c5b Merge pull request #215
4bc273b Merge pull request #222
137a8ec Merge pull request #216
7c3771d Disable overlength-strings warnings.
8956111 use 128-bit hex seed
02efd06 Use RFC6979 for test PRNGs
ae55e85 Use faster byteswapping and avoid alignment-increasing casts.
443cd4b Get rid of hex format and some binary conversions
0bada0e Merge #214: Improve signing API documentation & specification
8030d7c Improve signing API documentation & specification
7b2fc1c Merge #213: Removed gotos, which are hard to trace and maintain.
11690d3 Removed gotos, which are hard to trace and maintain.
122a1ec Merge pull request #205
035406d Merge pull request #206
2d4cd53 Merge pull request #161
34b898d Additional comments for the testing PRNG and a seeding fix.
6efd6e7 Some comments explaining some of the constants in the code.
ffccfd2 x86_64 assembly optimization for scalar_4x64
67cbdf0 Merge pull request #207
039723d Benchmarks for all internal operations
6cc8425 Include a comment on secp256k1_ecdsa_sign explaining low-s.
f88343f Merge pull request #203
d61e899 Add group operation counts
2473f17 Merge pull request #202
b5bbce6 Some readme updates, e.g. removal of the GMP field.
f0d851e Merge pull request #201
a0ea884 Merge pull request #200
f735446 Convert the rest of the codebase to C89.
bf2e1ac Convert tests to C89. (also fixes a use of bare "inline" in field)
fc8285f Merge pull request #199
fff412e Merge pull request #197
4be8d6f Centralize the definition of uint128_t and use it uniformly.
d9543c9 Switch scalar code to C89.
fcc48c4 Remove the non-storage cmov
55422b6 Switch ecmult_gen to use storage types
41f8455 Use group element storage type in EC multiplications
e68d720 Add group element storage type
ff889f7 Field storage type
7137be8 Merge pull request #196
0768bd5 Get rid of variable-length hex string conversions
e84e761 Merge pull request #195
792bcdb Covert several more files to C89.
45cdf44 Merge pull request #193
17db09e Merge pull request #194
402878a fix ifdef/ifndef
25b35c7 Convert field code to strict C89 (+ long long, +__int128)
3627437 C89 nits and dead code removal.
a9f350d Merge pull request #191
4732d26 Convert the field/group/ecdsa constant initialization to static consts
19f3e76 Remove unused secp256k1_fe_inner_{start, stop} functions
f1ebfe3 Convert the scalar constant initialization to static consts

git-subtree-dir: src/secp256k1
git-subtree-split: 1897b8e90bbbdcd919427c9a8ae35b420e919d8f

1 files changed, 63 insertions, 124 deletions

diff --git a/src/field_impl.h b/src/field_impl.h
index 4e2c24aa15..047914cf28 100644
--- a/src/field_impl.h
+++ b/src/field_impl.h
@@ -21,49 +21,6 @@
 #error "Please select field implementation"
 #endif
 
-static void secp256k1_fe_get_hex(char *r, int *rlen, const secp256k1_fe_t *a) {
-    if (*rlen < 65) {
-        *rlen = 65;
-        return;
-    }
-    *rlen = 65;
-    unsigned char tmp[32];
-    secp256k1_fe_t b = *a;
-    secp256k1_fe_normalize(&b);
-    secp256k1_fe_get_b32(tmp, &b);
-    for (int i=0; i<32; i++) {
-        static const char *c = "0123456789ABCDEF";
-        r[2*i]   = c[(tmp[i] >> 4) & 0xF];
-        r[2*i+1] = c[(tmp[i]) & 0xF];
-    }
-    r[64] = 0x00;
-}
-
-static int secp256k1_fe_set_hex(secp256k1_fe_t *r, const char *a, int alen) {
-    unsigned char tmp[32] = {};
-    static const int cvt[256] = {0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 1, 2, 3, 4, 5, 6,7,8,9,0,0,0,0,0,0,
-                                 0,10,11,12,13,14,15,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0,10,11,12,13,14,15,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0,
-                                 0, 0, 0, 0, 0, 0, 0,0,0,0,0,0,0,0,0,0};
-    for (int i=0; i<32; i++) {
-        if (alen > i*2)
-            tmp[32 - alen/2 + i] = (cvt[(unsigned char)a[2*i]] << 4) + cvt[(unsigned char)a[2*i+1]];
-    }
-    return secp256k1_fe_set_b32(r, tmp);
-}
-
 SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe_t *a, const secp256k1_fe_t *b) {
     secp256k1_fe_t na;
     secp256k1_fe_negate(&na, a, 1);
@@ -72,62 +29,62 @@ SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe_t *a, cons
 }
 
 static int secp256k1_fe_sqrt_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
+    int j;
 
     /** The binary representation of (p + 1)/4 has 3 blocks of 1s, with lengths in
      *  { 2, 22, 223 }. Use an addition chain to calculate 2^n - 1 for each block:
      *  1, [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223]
      */
 
-    secp256k1_fe_t x2;
     secp256k1_fe_sqr(&x2, a);
     secp256k1_fe_mul(&x2, &x2, a);
 
-    secp256k1_fe_t x3;
     secp256k1_fe_sqr(&x3, &x2);
     secp256k1_fe_mul(&x3, &x3, a);
 
-    secp256k1_fe_t x6 = x3;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
+    x6 = x3;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
     secp256k1_fe_mul(&x6, &x6, &x3);
 
-    secp256k1_fe_t x9 = x6;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
+    x9 = x6;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
     secp256k1_fe_mul(&x9, &x9, &x3);
 
-    secp256k1_fe_t x11 = x9;
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
+    x11 = x9;
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
     secp256k1_fe_mul(&x11, &x11, &x2);
 
-    secp256k1_fe_t x22 = x11;
-    for (int j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
+    x22 = x11;
+    for (j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
     secp256k1_fe_mul(&x22, &x22, &x11);
 
-    secp256k1_fe_t x44 = x22;
-    for (int j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
+    x44 = x22;
+    for (j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
     secp256k1_fe_mul(&x44, &x44, &x22);
 
-    secp256k1_fe_t x88 = x44;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
+    x88 = x44;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
     secp256k1_fe_mul(&x88, &x88, &x44);
 
-    secp256k1_fe_t x176 = x88;
-    for (int j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
+    x176 = x88;
+    for (j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
     secp256k1_fe_mul(&x176, &x176, &x88);
 
-    secp256k1_fe_t x220 = x176;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
+    x220 = x176;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
     secp256k1_fe_mul(&x220, &x220, &x44);
 
-    secp256k1_fe_t x223 = x220;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
+    x223 = x220;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
     secp256k1_fe_mul(&x223, &x223, &x3);
 
     /* The final result is then assembled using a sliding window over the blocks. */
 
-    secp256k1_fe_t t1 = x223;
-    for (int j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
+    t1 = x223;
+    for (j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x22);
-    for (int j=0; j<6; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<6; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x2);
     secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_sqr(r, &t1);
@@ -139,66 +96,66 @@ static int secp256k1_fe_sqrt_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 }
 
 static void secp256k1_fe_inv(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
+    int j;
 
     /** The binary representation of (p - 2) has 5 blocks of 1s, with lengths in
      *  { 1, 2, 22, 223 }. Use an addition chain to calculate 2^n - 1 for each block:
      *  [1], [2], 3, 6, 9, 11, [22], 44, 88, 176, 220, [223]
      */
 
-    secp256k1_fe_t x2;
     secp256k1_fe_sqr(&x2, a);
     secp256k1_fe_mul(&x2, &x2, a);
 
-    secp256k1_fe_t x3;
     secp256k1_fe_sqr(&x3, &x2);
     secp256k1_fe_mul(&x3, &x3, a);
 
-    secp256k1_fe_t x6 = x3;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
+    x6 = x3;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x6, &x6);
     secp256k1_fe_mul(&x6, &x6, &x3);
 
-    secp256k1_fe_t x9 = x6;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
+    x9 = x6;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x9, &x9);
     secp256k1_fe_mul(&x9, &x9, &x3);
 
-    secp256k1_fe_t x11 = x9;
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
+    x11 = x9;
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&x11, &x11);
     secp256k1_fe_mul(&x11, &x11, &x2);
 
-    secp256k1_fe_t x22 = x11;
-    for (int j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
+    x22 = x11;
+    for (j=0; j<11; j++) secp256k1_fe_sqr(&x22, &x22);
     secp256k1_fe_mul(&x22, &x22, &x11);
 
-    secp256k1_fe_t x44 = x22;
-    for (int j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
+    x44 = x22;
+    for (j=0; j<22; j++) secp256k1_fe_sqr(&x44, &x44);
     secp256k1_fe_mul(&x44, &x44, &x22);
 
-    secp256k1_fe_t x88 = x44;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
+    x88 = x44;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x88, &x88);
     secp256k1_fe_mul(&x88, &x88, &x44);
 
-    secp256k1_fe_t x176 = x88;
-    for (int j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
+    x176 = x88;
+    for (j=0; j<88; j++) secp256k1_fe_sqr(&x176, &x176);
     secp256k1_fe_mul(&x176, &x176, &x88);
 
-    secp256k1_fe_t x220 = x176;
-    for (int j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
+    x220 = x176;
+    for (j=0; j<44; j++) secp256k1_fe_sqr(&x220, &x220);
     secp256k1_fe_mul(&x220, &x220, &x44);
 
-    secp256k1_fe_t x223 = x220;
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
+    x223 = x220;
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&x223, &x223);
     secp256k1_fe_mul(&x223, &x223, &x3);
 
     /* The final result is then assembled using a sliding window over the blocks. */
 
-    secp256k1_fe_t t1 = x223;
-    for (int j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
+    t1 = x223;
+    for (j=0; j<23; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x22);
-    for (int j=0; j<5; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<5; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, a);
-    for (int j=0; j<3; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<3; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(&t1, &t1, &x2);
-    for (int j=0; j<2; j++) secp256k1_fe_sqr(&t1, &t1);
+    for (j=0; j<2; j++) secp256k1_fe_sqr(&t1, &t1);
     secp256k1_fe_mul(r, a, &t1);
 }
 
@@ -206,13 +163,21 @@ static void secp256k1_fe_inv_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 #if defined(USE_FIELD_INV_BUILTIN)
     secp256k1_fe_inv(r, a);
 #elif defined(USE_FIELD_INV_NUM)
+    secp256k1_num_t n, m;
+    /* secp256k1 field prime, value p defined in "Standards for Efficient Cryptography" (SEC2) 2.7.1. */
+    static const unsigned char prime[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,0x2F
+    };
     unsigned char b[32];
     secp256k1_fe_t c = *a;
     secp256k1_fe_normalize_var(&c);
     secp256k1_fe_get_b32(b, &c);
-    secp256k1_num_t n;
     secp256k1_num_set_bin(&n, b, 32);
-    secp256k1_num_mod_inverse(&n, &n, &secp256k1_fe_consts->p);
+    secp256k1_num_set_bin(&m, prime, 32);
+    secp256k1_num_mod_inverse(&n, &n, &m);
     secp256k1_num_get_bin(b, 32, &n);
     VERIFY_CHECK(secp256k1_fe_set_b32(r, b));
 #else
@@ -220,7 +185,9 @@ static void secp256k1_fe_inv_var(secp256k1_fe_t *r, const secp256k1_fe_t *a) {
 #endif
 }
 
-static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t r[len], const secp256k1_fe_t a[len]) {
+static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t *r, const secp256k1_fe_t *a) {
+    secp256k1_fe_t u;
+    size_t i;
     if (len < 1)
         return;
 
@@ -228,12 +195,12 @@ static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t r[len], const se
 
     r[0] = a[0];
 
-    size_t i = 0;
+    i = 0;
     while (++i < len) {
         secp256k1_fe_mul(&r[i], &r[i - 1], &a[i]);
     }
 
-    secp256k1_fe_t u; secp256k1_fe_inv_var(&u, &r[--i]);
+    secp256k1_fe_inv_var(&u, &r[--i]);
 
     while (i > 0) {
         int j = i--;
@@ -244,32 +211,4 @@ static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe_t r[len], const se
     r[0] = u;
 }
 
-static void secp256k1_fe_start(void) {
-#ifndef USE_NUM_NONE
-    static const unsigned char secp256k1_fe_consts_p[] = {
-        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
-    };
-#endif
-    if (secp256k1_fe_consts == NULL) {
-        secp256k1_fe_inner_start();
-        secp256k1_fe_consts_t *ret = (secp256k1_fe_consts_t*)checked_malloc(sizeof(secp256k1_fe_consts_t));
-#ifndef USE_NUM_NONE
-        secp256k1_num_set_bin(&ret->p, secp256k1_fe_consts_p, sizeof(secp256k1_fe_consts_p));
-#endif
-        secp256k1_fe_consts = ret;
-    }
-}
-
-static void secp256k1_fe_stop(void) {
-    if (secp256k1_fe_consts != NULL) {
-        secp256k1_fe_consts_t *c = (secp256k1_fe_consts_t*)secp256k1_fe_consts;
-        free((void*)c);
-        secp256k1_fe_consts = NULL;
-        secp256k1_fe_inner_stop();
-    }
-}
-
 #endif