diff options
Diffstat (limited to 'crypto/secp256k1/libsecp256k1/src/num_gmp_impl.h')
-rw-r--r-- | crypto/secp256k1/libsecp256k1/src/num_gmp_impl.h | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/crypto/secp256k1/libsecp256k1/src/num_gmp_impl.h b/crypto/secp256k1/libsecp256k1/src/num_gmp_impl.h new file mode 100644 index 000000000..f43e7a56c --- /dev/null +++ b/crypto/secp256k1/libsecp256k1/src/num_gmp_impl.h @@ -0,0 +1,260 @@ +/********************************************************************** + * 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_NUM_REPR_IMPL_H_ +#define _SECP256K1_NUM_REPR_IMPL_H_ + +#include <string.h> +#include <stdlib.h> +#include <gmp.h> + +#include "util.h" +#include "num.h" + +#ifdef VERIFY +static void secp256k1_num_sanity(const secp256k1_num *a) { + VERIFY_CHECK(a->limbs == 1 || (a->limbs > 1 && a->data[a->limbs-1] != 0)); +} +#else +#define secp256k1_num_sanity(a) do { } while(0) +#endif + +static void secp256k1_num_copy(secp256k1_num *r, const secp256k1_num *a) { + *r = *a; +} + +static void secp256k1_num_get_bin(unsigned char *r, unsigned int rlen, const secp256k1_num *a) { + unsigned char tmp[65]; + int len = 0; + int shift = 0; + if (a->limbs>1 || a->data[0] != 0) { + len = mpn_get_str(tmp, 256, (mp_limb_t*)a->data, a->limbs); + } + while (shift < len && tmp[shift] == 0) shift++; + VERIFY_CHECK(len-shift <= (int)rlen); + memset(r, 0, rlen - len + shift); + if (len > shift) { + memcpy(r + rlen - len + shift, tmp + shift, len - shift); + } + memset(tmp, 0, sizeof(tmp)); +} + +static void secp256k1_num_set_bin(secp256k1_num *r, const unsigned char *a, unsigned int alen) { + int len; + VERIFY_CHECK(alen > 0); + VERIFY_CHECK(alen <= 64); + len = mpn_set_str(r->data, a, alen, 256); + if (len == 0) { + r->data[0] = 0; + len = 1; + } + VERIFY_CHECK(len <= NUM_LIMBS*2); + r->limbs = len; + r->neg = 0; + while (r->limbs > 1 && r->data[r->limbs-1]==0) { + r->limbs--; + } +} + +static void secp256k1_num_add_abs(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) { + mp_limb_t c = mpn_add(r->data, a->data, a->limbs, b->data, b->limbs); + r->limbs = a->limbs; + if (c != 0) { + VERIFY_CHECK(r->limbs < 2*NUM_LIMBS); + r->data[r->limbs++] = c; + } +} + +static void secp256k1_num_sub_abs(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) { + mp_limb_t c = mpn_sub(r->data, a->data, a->limbs, b->data, b->limbs); + VERIFY_CHECK(c == 0); + r->limbs = a->limbs; + while (r->limbs > 1 && r->data[r->limbs-1]==0) { + r->limbs--; + } +} + +static void secp256k1_num_mod(secp256k1_num *r, const secp256k1_num *m) { + secp256k1_num_sanity(r); + secp256k1_num_sanity(m); + + if (r->limbs >= m->limbs) { + mp_limb_t t[2*NUM_LIMBS]; + mpn_tdiv_qr(t, r->data, 0, r->data, r->limbs, m->data, m->limbs); + memset(t, 0, sizeof(t)); + r->limbs = m->limbs; + while (r->limbs > 1 && r->data[r->limbs-1]==0) { + r->limbs--; + } + } + + if (r->neg && (r->limbs > 1 || r->data[0] != 0)) { + secp256k1_num_sub_abs(r, m, r); + r->neg = 0; + } +} + +static void secp256k1_num_mod_inverse(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *m) { + int i; + mp_limb_t g[NUM_LIMBS+1]; + mp_limb_t u[NUM_LIMBS+1]; + mp_limb_t v[NUM_LIMBS+1]; + mp_size_t sn; + mp_size_t gn; + secp256k1_num_sanity(a); + secp256k1_num_sanity(m); + + /** mpn_gcdext computes: (G,S) = gcdext(U,V), where + * * G = gcd(U,V) + * * G = U*S + V*T + * * U has equal or more limbs than V, and V has no padding + * If we set U to be (a padded version of) a, and V = m: + * G = a*S + m*T + * G = a*S mod m + * Assuming G=1: + * S = 1/a mod m + */ + VERIFY_CHECK(m->limbs <= NUM_LIMBS); + VERIFY_CHECK(m->data[m->limbs-1] != 0); + for (i = 0; i < m->limbs; i++) { + u[i] = (i < a->limbs) ? a->data[i] : 0; + v[i] = m->data[i]; + } + sn = NUM_LIMBS+1; + gn = mpn_gcdext(g, r->data, &sn, u, m->limbs, v, m->limbs); + VERIFY_CHECK(gn == 1); + VERIFY_CHECK(g[0] == 1); + r->neg = a->neg ^ m->neg; + if (sn < 0) { + mpn_sub(r->data, m->data, m->limbs, r->data, -sn); + r->limbs = m->limbs; + while (r->limbs > 1 && r->data[r->limbs-1]==0) { + r->limbs--; + } + } else { + r->limbs = sn; + } + memset(g, 0, sizeof(g)); + memset(u, 0, sizeof(u)); + memset(v, 0, sizeof(v)); +} + +static int secp256k1_num_is_zero(const secp256k1_num *a) { + return (a->limbs == 1 && a->data[0] == 0); +} + +static int secp256k1_num_is_neg(const secp256k1_num *a) { + return (a->limbs > 1 || a->data[0] != 0) && a->neg; +} + +static int secp256k1_num_cmp(const secp256k1_num *a, const secp256k1_num *b) { + if (a->limbs > b->limbs) { + return 1; + } + if (a->limbs < b->limbs) { + return -1; + } + return mpn_cmp(a->data, b->data, a->limbs); +} + +static int secp256k1_num_eq(const secp256k1_num *a, const secp256k1_num *b) { + if (a->limbs > b->limbs) { + return 0; + } + if (a->limbs < b->limbs) { + return 0; + } + if ((a->neg && !secp256k1_num_is_zero(a)) != (b->neg && !secp256k1_num_is_zero(b))) { + return 0; + } + return mpn_cmp(a->data, b->data, a->limbs) == 0; +} + +static void secp256k1_num_subadd(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b, int bneg) { + if (!(b->neg ^ bneg ^ a->neg)) { /* a and b have the same sign */ + r->neg = a->neg; + if (a->limbs >= b->limbs) { + secp256k1_num_add_abs(r, a, b); + } else { + secp256k1_num_add_abs(r, b, a); + } + } else { + if (secp256k1_num_cmp(a, b) > 0) { + r->neg = a->neg; + secp256k1_num_sub_abs(r, a, b); + } else { + r->neg = b->neg ^ bneg; + secp256k1_num_sub_abs(r, b, a); + } + } +} + +static void secp256k1_num_add(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) { + secp256k1_num_sanity(a); + secp256k1_num_sanity(b); + secp256k1_num_subadd(r, a, b, 0); +} + +static void secp256k1_num_sub(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) { + secp256k1_num_sanity(a); + secp256k1_num_sanity(b); + secp256k1_num_subadd(r, a, b, 1); +} + +static void secp256k1_num_mul(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) { + mp_limb_t tmp[2*NUM_LIMBS+1]; + secp256k1_num_sanity(a); + secp256k1_num_sanity(b); + + VERIFY_CHECK(a->limbs + b->limbs <= 2*NUM_LIMBS+1); + if ((a->limbs==1 && a->data[0]==0) || (b->limbs==1 && b->data[0]==0)) { + r->limbs = 1; + r->neg = 0; + r->data[0] = 0; + return; + } + if (a->limbs >= b->limbs) { + mpn_mul(tmp, a->data, a->limbs, b->data, b->limbs); + } else { + mpn_mul(tmp, b->data, b->limbs, a->data, a->limbs); + } + r->limbs = a->limbs + b->limbs; + if (r->limbs > 1 && tmp[r->limbs - 1]==0) { + r->limbs--; + } + VERIFY_CHECK(r->limbs <= 2*NUM_LIMBS); + mpn_copyi(r->data, tmp, r->limbs); + r->neg = a->neg ^ b->neg; + memset(tmp, 0, sizeof(tmp)); +} + +static void secp256k1_num_shift(secp256k1_num *r, int bits) { + if (bits % GMP_NUMB_BITS) { + /* Shift within limbs. */ + mpn_rshift(r->data, r->data, r->limbs, bits % GMP_NUMB_BITS); + } + if (bits >= GMP_NUMB_BITS) { + int i; + /* Shift full limbs. */ + for (i = 0; i < r->limbs; i++) { + int index = i + (bits / GMP_NUMB_BITS); + if (index < r->limbs && index < 2*NUM_LIMBS) { + r->data[i] = r->data[index]; + } else { + r->data[i] = 0; + } + } + } + while (r->limbs>1 && r->data[r->limbs-1]==0) { + r->limbs--; + } +} + +static void secp256k1_num_negate(secp256k1_num *r) { + r->neg ^= 1; +} + +#endif |