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secp256k1
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Make lambda constant accessible

This commit is contained in:
Pieter Wuille 2020-10-11 10:49:54 -07:00
parent 9d2f2b44d8
commit fe7fc1fda8
1 changed files with 8 additions and 11 deletions
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19
src/scalar_impl.h
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@ -434,17 +434,17 @@ static void secp256k1_scalar_split_lambda(secp256k1_scalar *r1, secp256k1_scalar
* Q.E.D. * Q.E.D.
*/ */
static const secp256k1_scalar secp256k1_const_lambda = SECP256K1_SCALAR_CONST(
0x5363AD4CUL, 0xC05C30E0UL, 0xA5261C02UL, 0x8812645AUL,
0x122E22EAUL, 0x20816678UL, 0xDF02967CUL, 0x1B23BD72UL
);
#ifdef VERIFY #ifdef VERIFY
static void secp256k1_scalar_split_lambda_verify(const secp256k1_scalar *r1, const secp256k1_scalar *r2, const secp256k1_scalar *k) { static void secp256k1_scalar_split_lambda_verify(const secp256k1_scalar *r1, const secp256k1_scalar *r2, const secp256k1_scalar *k) {
secp256k1_scalar s; secp256k1_scalar s;
unsigned char buf1[32]; unsigned char buf1[32];
unsigned char buf2[32]; unsigned char buf2[32];
static const secp256k1_scalar lambda = SECP256K1_SCALAR_CONST(
0x5363AD4CUL, 0xC05C30E0UL, 0xA5261C02UL, 0x8812645AUL,
0x122E22EAUL, 0x20816678UL, 0xDF02967CUL, 0x1B23BD72UL
);
/* (a1 + a2 + 1)/2 is 0xa2a8918ca85bafe22016d0b917e4dd77 */ /* (a1 + a2 + 1)/2 is 0xa2a8918ca85bafe22016d0b917e4dd77 */
static const unsigned char k1_bound[32] = { static const unsigned char k1_bound[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,
@ -457,7 +457,7 @@ static void secp256k1_scalar_split_lambda_verify(const secp256k1_scalar *r1, con
0x8a, 0x65, 0x28, 0x7b, 0xd4, 0x71, 0x79, 0xfb, 0x2b, 0xe0, 0x88, 0x46, 0xce, 0xa2, 0x67, 0xed 0x8a, 0x65, 0x28, 0x7b, 0xd4, 0x71, 0x79, 0xfb, 0x2b, 0xe0, 0x88, 0x46, 0xce, 0xa2, 0x67, 0xed
}; };
secp256k1_scalar_mul(&s, &lambda, r2); secp256k1_scalar_mul(&s, &secp256k1_const_lambda, r2);
secp256k1_scalar_add(&s, &s, r1); secp256k1_scalar_add(&s, &s, r1);
VERIFY_CHECK(secp256k1_scalar_eq(&s, k)); VERIFY_CHECK(secp256k1_scalar_eq(&s, k));
@ -475,10 +475,6 @@ static void secp256k1_scalar_split_lambda_verify(const secp256k1_scalar *r1, con
static void secp256k1_scalar_split_lambda(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *k) { static void secp256k1_scalar_split_lambda(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *k) {
secp256k1_scalar c1, c2; secp256k1_scalar c1, c2;
static const secp256k1_scalar minus_lambda = SECP256K1_SCALAR_CONST(
0xAC9C52B3UL, 0x3FA3CF1FUL, 0x5AD9E3FDUL, 0x77ED9BA4UL,
0xA880B9FCUL, 0x8EC739C2UL, 0xE0CFC810UL, 0xB51283CFUL
);
static const secp256k1_scalar minus_b1 = SECP256K1_SCALAR_CONST( static const secp256k1_scalar minus_b1 = SECP256K1_SCALAR_CONST(
0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL,
0xE4437ED6UL, 0x010E8828UL, 0x6F547FA9UL, 0x0ABFE4C3UL 0xE4437ED6UL, 0x010E8828UL, 0x6F547FA9UL, 0x0ABFE4C3UL
@ -503,7 +499,8 @@ static void secp256k1_scalar_split_lambda(secp256k1_scalar *r1, secp256k1_scalar
secp256k1_scalar_mul(&c1, &c1, &minus_b1); secp256k1_scalar_mul(&c1, &c1, &minus_b1);
secp256k1_scalar_mul(&c2, &c2, &minus_b2); secp256k1_scalar_mul(&c2, &c2, &minus_b2);
secp256k1_scalar_add(r2, &c1, &c2); secp256k1_scalar_add(r2, &c1, &c2);
secp256k1_scalar_mul(r1, r2, &minus_lambda); secp256k1_scalar_mul(r1, r2, &secp256k1_const_lambda);
secp256k1_scalar_negate(r1, r1);
secp256k1_scalar_add(r1, r1, k); secp256k1_scalar_add(r1, r1, k);
#ifdef VERIFY #ifdef VERIFY