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crypto/secp256k1: update to github.com/bitcoin-core/secp256k1 @ 9d560f9 (#3544)

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- Use defined constants instead of hard-coding their integer value.
- Allocate secp256k1 structs on the C stack instead of converting []byte
- Remove dead code
This commit is contained in:
Felix Lange
2017-01-12 21:29:11 +01:00
committed by GitHub
parent 93077c98e4
commit e0ceeab0d1
79 changed files with 8242 additions and 2011 deletions
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52
crypto/secp256k1/libsecp256k1/src/field_impl.h
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@@ -21,6 +21,13 @@
#error "Please select field implementation"
#endif
SECP256K1_INLINE static int secp256k1_fe_equal(const secp256k1_fe *a, const secp256k1_fe *b) {
secp256k1_fe na;
secp256k1_fe_negate(&na, a, 1);
secp256k1_fe_add(&na, b);
return secp256k1_fe_normalizes_to_zero(&na);
}
SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe *a, const secp256k1_fe *b) {
secp256k1_fe na;
secp256k1_fe_negate(&na, a, 1);
@@ -28,7 +35,16 @@ SECP256K1_INLINE static int secp256k1_fe_equal_var(const secp256k1_fe *a, const
return secp256k1_fe_normalizes_to_zero_var(&na);
}
static int secp256k1_fe_sqrt_var(secp256k1_fe *r, const secp256k1_fe *a) {
static int secp256k1_fe_sqrt(secp256k1_fe *r, const secp256k1_fe *a) {
/** Given that p is congruent to 3 mod 4, we can compute the square root of
* a mod p as the (p+1)/4'th power of a.
*
* As (p+1)/4 is an even number, it will have the same result for a and for
* (-a). Only one of these two numbers actually has a square root however,
* so we test at the end by squaring and comparing to the input.
* Also because (p+1)/4 is an even number, the computed square root is
* itself always a square (a ** ((p+1)/4) is the square of a ** ((p+1)/8)).
*/
secp256k1_fe x2, x3, x6, x9, x11, x22, x44, x88, x176, x220, x223, t1;
int j;
@@ -114,7 +130,7 @@ static int secp256k1_fe_sqrt_var(secp256k1_fe *r, const secp256k1_fe *a) {
/* Check that a square root was actually calculated */
secp256k1_fe_sqr(&t1, r);
return secp256k1_fe_equal_var(&t1, a);
return secp256k1_fe_equal(&t1, a);
}
static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *a) {
@@ -224,6 +240,7 @@ static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) {
0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F
};
unsigned char b[32];
int res;
secp256k1_fe c = *a;
secp256k1_fe_normalize_var(&c);
secp256k1_fe_get_b32(b, &c);
@@ -231,7 +248,9 @@ static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) {
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));
res = secp256k1_fe_set_b32(r, b);
(void)res;
VERIFY_CHECK(res);
/* Verify the result is the (unique) valid inverse using non-GMP code. */
secp256k1_fe_mul(&c, &c, r);
secp256k1_fe_add(&c, &negone);
@@ -241,7 +260,7 @@ static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) {
#endif
}
static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe *r, const secp256k1_fe *a) {
static void secp256k1_fe_inv_all_var(secp256k1_fe *r, const secp256k1_fe *a, size_t len) {
secp256k1_fe u;
size_t i;
if (len < 1) {
@@ -268,4 +287,29 @@ static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe *r, const secp256k
r[0] = u;
}
static int secp256k1_fe_is_quad_var(const secp256k1_fe *a) {
#ifndef USE_NUM_NONE
unsigned char b[32];
secp256k1_num n;
secp256k1_num 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
};
secp256k1_fe c = *a;
secp256k1_fe_normalize_var(&c);
secp256k1_fe_get_b32(b, &c);
secp256k1_num_set_bin(&n, b, 32);
secp256k1_num_set_bin(&m, prime, 32);
return secp256k1_num_jacobi(&n, &m) >= 0;
#else
secp256k1_fe r;
return secp256k1_fe_sqrt(&r, a);
#endif
}
#endif