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Import code from previous AssetBuilder version
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163
thirdparty/libtomcrypt/pk/ecc/ltc_ecc_mulmod_timing.c
vendored
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163
thirdparty/libtomcrypt/pk/ecc/ltc_ecc_mulmod_timing.c
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
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*
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* All curves taken from NIST recommendation paper of July 1999
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* Available at http://csrc.nist.gov/cryptval/dss.htm
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*/
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#include "tomcrypt.h"
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/**
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@file ltc_ecc_mulmod_timing.c
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ECC Crypto, Tom St Denis
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*/
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#ifdef LTC_MECC
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#ifdef LTC_ECC_TIMING_RESISTANT
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/**
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Perform a point multiplication (timing resistant)
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@param k The scalar to multiply by
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@param G The base point
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@param R [out] Destination for kG
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@param modulus The modulus of the field the ECC curve is in
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@param map Boolean whether to map back to affine or not (1==map, 0 == leave in projective)
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@return CRYPT_OK on success
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*/
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int ltc_ecc_mulmod(void *k, ecc_point *G, ecc_point *R, void *modulus, int map)
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{
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ecc_point *tG, *M[3];
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int i, j, err;
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void *mu, *mp;
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ltc_mp_digit buf;
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int bitcnt, mode, digidx;
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LTC_ARGCHK(k != NULL);
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LTC_ARGCHK(G != NULL);
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LTC_ARGCHK(R != NULL);
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LTC_ARGCHK(modulus != NULL);
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/* init montgomery reduction */
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if ((err = mp_montgomery_setup(modulus, &mp)) != CRYPT_OK) {
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return err;
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}
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if ((err = mp_init(&mu)) != CRYPT_OK) {
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mp_montgomery_free(mp);
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return err;
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}
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if ((err = mp_montgomery_normalization(mu, modulus)) != CRYPT_OK) {
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mp_clear(mu);
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mp_montgomery_free(mp);
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return err;
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}
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/* alloc ram for window temps */
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for (i = 0; i < 3; i++) {
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M[i] = ltc_ecc_new_point();
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if (M[i] == NULL) {
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for (j = 0; j < i; j++) {
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ltc_ecc_del_point(M[j]);
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}
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mp_clear(mu);
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mp_montgomery_free(mp);
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return CRYPT_MEM;
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}
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}
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/* make a copy of G incase R==G */
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tG = ltc_ecc_new_point();
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if (tG == NULL) { err = CRYPT_MEM; goto done; }
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/* tG = G and convert to montgomery */
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if ((err = mp_mulmod(G->x, mu, modulus, tG->x)) != CRYPT_OK) { goto done; }
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if ((err = mp_mulmod(G->y, mu, modulus, tG->y)) != CRYPT_OK) { goto done; }
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if ((err = mp_mulmod(G->z, mu, modulus, tG->z)) != CRYPT_OK) { goto done; }
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mp_clear(mu);
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mu = NULL;
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/* calc the M tab */
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/* M[0] == G */
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if ((err = mp_copy(tG->x, M[0]->x)) != CRYPT_OK) { goto done; }
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if ((err = mp_copy(tG->y, M[0]->y)) != CRYPT_OK) { goto done; }
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if ((err = mp_copy(tG->z, M[0]->z)) != CRYPT_OK) { goto done; }
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/* M[1] == 2G */
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if ((err = ltc_mp.ecc_ptdbl(tG, M[1], modulus, mp)) != CRYPT_OK) { goto done; }
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/* setup sliding window */
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mode = 0;
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bitcnt = 1;
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buf = 0;
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digidx = mp_get_digit_count(k) - 1;
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/* perform ops */
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for (;;) {
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/* grab next digit as required */
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if (--bitcnt == 0) {
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if (digidx == -1) {
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break;
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}
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buf = mp_get_digit(k, digidx);
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bitcnt = (int) MP_DIGIT_BIT;
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--digidx;
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}
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/* grab the next msb from the ltiplicand */
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i = (buf >> (MP_DIGIT_BIT - 1)) & 1;
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buf <<= 1;
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if (mode == 0 && i == 0) {
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/* dummy operations */
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if ((err = ltc_mp.ecc_ptadd(M[0], M[1], M[2], modulus, mp)) != CRYPT_OK) { goto done; }
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if ((err = ltc_mp.ecc_ptdbl(M[1], M[2], modulus, mp)) != CRYPT_OK) { goto done; }
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continue;
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}
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if (mode == 0 && i == 1) {
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mode = 1;
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/* dummy operations */
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if ((err = ltc_mp.ecc_ptadd(M[0], M[1], M[2], modulus, mp)) != CRYPT_OK) { goto done; }
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if ((err = ltc_mp.ecc_ptdbl(M[1], M[2], modulus, mp)) != CRYPT_OK) { goto done; }
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continue;
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}
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if ((err = ltc_mp.ecc_ptadd(M[0], M[1], M[i^1], modulus, mp)) != CRYPT_OK) { goto done; }
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if ((err = ltc_mp.ecc_ptdbl(M[i], M[i], modulus, mp)) != CRYPT_OK) { goto done; }
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}
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/* copy result out */
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if ((err = mp_copy(M[0]->x, R->x)) != CRYPT_OK) { goto done; }
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if ((err = mp_copy(M[0]->y, R->y)) != CRYPT_OK) { goto done; }
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if ((err = mp_copy(M[0]->z, R->z)) != CRYPT_OK) { goto done; }
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/* map R back from projective space */
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if (map) {
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err = ltc_ecc_map(R, modulus, mp);
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} else {
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err = CRYPT_OK;
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}
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done:
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if (mu != NULL) {
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mp_clear(mu);
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}
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mp_montgomery_free(mp);
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ltc_ecc_del_point(tG);
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for (i = 0; i < 3; i++) {
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ltc_ecc_del_point(M[i]);
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}
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return err;
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}
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#endif
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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