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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.
*/
static const secp256k1_scalar secp256k1_const_lambda = SECP256K1_SCALAR_CONST(
0x5363AD4CUL, 0xC05C30E0UL, 0xA5261C02UL, 0x8812645AUL,
0x122E22EAUL, 0x20816678UL, 0xDF02967CUL, 0x1B23BD72UL
);
#ifdef VERIFY
static void secp256k1_scalar_split_lambda_verify(const secp256k1_scalar *r1, const secp256k1_scalar *r2, const secp256k1_scalar *k) {
secp256k1_scalar s;
unsigned char buf1[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 */
static const unsigned char k1_bound[32] = {
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
};
secp256k1_scalar_mul(&s, &lambda, r2);
secp256k1_scalar_mul(&s, &secp256k1_const_lambda, r2);
secp256k1_scalar_add(&s, &s, r1);
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) {
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(
0x00000000UL, 0x00000000UL, 0x00000000UL, 0x00000000UL,
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(&c2, &c2, &minus_b2);
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);
#ifdef VERIFY