From 1d20b0247c35f440d3fdc3d21de19b2d5256c3cf Mon Sep 17 00:00:00 2001 From: Gustav Simonsson Date: Mon, 28 Sep 2015 17:46:17 +0200 Subject: Update libsecp256k1 --- crypto/secp256k1/libsecp256k1/src/field_impl.h | 271 +++++++++++++++++++++++++ 1 file changed, 271 insertions(+) create mode 100644 crypto/secp256k1/libsecp256k1/src/field_impl.h (limited to 'crypto/secp256k1/libsecp256k1/src/field_impl.h') diff --git a/crypto/secp256k1/libsecp256k1/src/field_impl.h b/crypto/secp256k1/libsecp256k1/src/field_impl.h new file mode 100644 index 000000000..551a6243e --- /dev/null +++ b/crypto/secp256k1/libsecp256k1/src/field_impl.h @@ -0,0 +1,271 @@ +/********************************************************************** + * Copyright (c) 2013, 2014 Pieter Wuille * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or http://www.opensource.org/licenses/mit-license.php.* + **********************************************************************/ + +#ifndef _SECP256K1_FIELD_IMPL_H_ +#define _SECP256K1_FIELD_IMPL_H_ + +#if defined HAVE_CONFIG_H +#include "libsecp256k1-config.h" +#endif + +#include "util.h" + +#if defined(USE_FIELD_10X26) +#include "field_10x26_impl.h" +#elif defined(USE_FIELD_5X52) +#include "field_5x52_impl.h" +#else +#error "Please select field implementation" +#endif + +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); + secp256k1_fe_add(&na, b); + return secp256k1_fe_normalizes_to_zero_var(&na); +} + +static int secp256k1_fe_sqrt_var(secp256k1_fe *r, const secp256k1_fe *a) { + secp256k1_fe 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_sqr(&x2, a); + secp256k1_fe_mul(&x2, &x2, a); + + secp256k1_fe_sqr(&x3, &x2); + secp256k1_fe_mul(&x3, &x3, a); + + x6 = x3; + for (j=0; j<3; j++) { + secp256k1_fe_sqr(&x6, &x6); + } + secp256k1_fe_mul(&x6, &x6, &x3); + + x9 = x6; + for (j=0; j<3; j++) { + secp256k1_fe_sqr(&x9, &x9); + } + secp256k1_fe_mul(&x9, &x9, &x3); + + x11 = x9; + for (j=0; j<2; j++) { + secp256k1_fe_sqr(&x11, &x11); + } + secp256k1_fe_mul(&x11, &x11, &x2); + + x22 = x11; + for (j=0; j<11; j++) { + secp256k1_fe_sqr(&x22, &x22); + } + secp256k1_fe_mul(&x22, &x22, &x11); + + x44 = x22; + for (j=0; j<22; j++) { + secp256k1_fe_sqr(&x44, &x44); + } + secp256k1_fe_mul(&x44, &x44, &x22); + + x88 = x44; + for (j=0; j<44; j++) { + secp256k1_fe_sqr(&x88, &x88); + } + secp256k1_fe_mul(&x88, &x88, &x44); + + x176 = x88; + for (j=0; j<88; j++) { + secp256k1_fe_sqr(&x176, &x176); + } + secp256k1_fe_mul(&x176, &x176, &x88); + + x220 = x176; + for (j=0; j<44; j++) { + secp256k1_fe_sqr(&x220, &x220); + } + secp256k1_fe_mul(&x220, &x220, &x44); + + 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. */ + + t1 = x223; + for (j=0; j<23; j++) { + secp256k1_fe_sqr(&t1, &t1); + } + secp256k1_fe_mul(&t1, &t1, &x22); + 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); + + /* Check that a square root was actually calculated */ + + secp256k1_fe_sqr(&t1, r); + return secp256k1_fe_equal_var(&t1, a); +} + +static void secp256k1_fe_inv(secp256k1_fe *r, const secp256k1_fe *a) { + secp256k1_fe 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_sqr(&x2, a); + secp256k1_fe_mul(&x2, &x2, a); + + secp256k1_fe_sqr(&x3, &x2); + secp256k1_fe_mul(&x3, &x3, a); + + x6 = x3; + for (j=0; j<3; j++) { + secp256k1_fe_sqr(&x6, &x6); + } + secp256k1_fe_mul(&x6, &x6, &x3); + + x9 = x6; + for (j=0; j<3; j++) { + secp256k1_fe_sqr(&x9, &x9); + } + secp256k1_fe_mul(&x9, &x9, &x3); + + x11 = x9; + for (j=0; j<2; j++) { + secp256k1_fe_sqr(&x11, &x11); + } + secp256k1_fe_mul(&x11, &x11, &x2); + + x22 = x11; + for (j=0; j<11; j++) { + secp256k1_fe_sqr(&x22, &x22); + } + secp256k1_fe_mul(&x22, &x22, &x11); + + x44 = x22; + for (j=0; j<22; j++) { + secp256k1_fe_sqr(&x44, &x44); + } + secp256k1_fe_mul(&x44, &x44, &x22); + + x88 = x44; + for (j=0; j<44; j++) { + secp256k1_fe_sqr(&x88, &x88); + } + secp256k1_fe_mul(&x88, &x88, &x44); + + x176 = x88; + for (j=0; j<88; j++) { + secp256k1_fe_sqr(&x176, &x176); + } + secp256k1_fe_mul(&x176, &x176, &x88); + + x220 = x176; + for (j=0; j<44; j++) { + secp256k1_fe_sqr(&x220, &x220); + } + secp256k1_fe_mul(&x220, &x220, &x44); + + 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. */ + + t1 = x223; + for (j=0; j<23; j++) { + secp256k1_fe_sqr(&t1, &t1); + } + secp256k1_fe_mul(&t1, &t1, &x22); + for (j=0; j<5; j++) { + secp256k1_fe_sqr(&t1, &t1); + } + secp256k1_fe_mul(&t1, &t1, a); + for (j=0; j<3; j++) { + secp256k1_fe_sqr(&t1, &t1); + } + secp256k1_fe_mul(&t1, &t1, &x2); + for (j=0; j<2; j++) { + secp256k1_fe_sqr(&t1, &t1); + } + secp256k1_fe_mul(r, a, &t1); +} + +static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) { +#if defined(USE_FIELD_INV_BUILTIN) + secp256k1_fe_inv(r, a); +#elif defined(USE_FIELD_INV_NUM) + secp256k1_num n, m; + static const secp256k1_fe negone = SECP256K1_FE_CONST( + 0xFFFFFFFFUL, 0xFFFFFFFFUL, 0xFFFFFFFFUL, 0xFFFFFFFFUL, + 0xFFFFFFFFUL, 0xFFFFFFFFUL, 0xFFFFFFFEUL, 0xFFFFFC2EUL + ); + /* 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 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); + secp256k1_num_mod_inverse(&n, &n, &m); + secp256k1_num_get_bin(b, 32, &n); + VERIFY_CHECK(secp256k1_fe_set_b32(r, b)); + /* Verify the result is the (unique) valid inverse using non-GMP code. */ + secp256k1_fe_mul(&c, &c, r); + secp256k1_fe_add(&c, &negone); + CHECK(secp256k1_fe_normalizes_to_zero_var(&c)); +#else +#error "Please select field inverse implementation" +#endif +} + +static void secp256k1_fe_inv_all_var(size_t len, secp256k1_fe *r, const secp256k1_fe *a) { + secp256k1_fe u; + size_t i; + if (len < 1) { + return; + } + + VERIFY_CHECK((r + len <= a) || (a + len <= r)); + + r[0] = a[0]; + + i = 0; + while (++i < len) { + secp256k1_fe_mul(&r[i], &r[i - 1], &a[i]); + } + + secp256k1_fe_inv_var(&u, &r[--i]); + + while (i > 0) { + size_t j = i--; + secp256k1_fe_mul(&r[j], &r[i], &u); + secp256k1_fe_mul(&u, &u, &a[j]); + } + + r[0] = u; +} + +#endif -- cgit