mirror of https://github.com/wolfSSL/wolfssl
add ecc timing mulmod
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toddouska
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20e8e4e0a2
commit
9d4fb79009
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@ -1160,6 +1160,168 @@ static int ecc_mulmod(mp_int* k, ecc_point *G, ecc_point *R, mp_int* modulus,
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}
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#undef WINSIZE
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#else /* ECC_TIMING_RESISTANT */
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/**
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Perform a point multiplication (timing resistant)
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k The scalar to multiply by
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G The base point
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R [out] Destination for kG
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modulus The modulus of the field the ECC curve is in
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map Boolean whether to map back to affine or not
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(1==map, 0 == leave in projective)
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return MP_OKAY on success
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*/
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#ifdef FP_ECC
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static int normal_ecc_mulmod(mp_int* k, ecc_point *G, ecc_point *R,
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mp_int* modulus, int map)
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#else
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static int ecc_mulmod(mp_int* k, ecc_point *G, ecc_point *R, mp_int* modulus,
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int map)
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#endif
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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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mp_int mu;
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mp_digit mp;
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unsigned long buf;
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int first = 1, bitbuf = 0, bitcpy = 0, bitcnt = 0, mode = 0,
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digidx = 0;
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if (k == NULL || G == NULL || R == NULL || modulus == NULL)
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return ECC_BAD_ARG_E;
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/* init montgomery reduction */
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if ((err = mp_montgomery_setup(modulus, &mp)) != MP_OKAY) {
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return err;
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}
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if ((err = mp_init(&mu)) != MP_OKAY) {
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return err;
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}
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if ((err = mp_montgomery_calc_normalization(&mu, modulus)) != MP_OKAY) {
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mp_clear(&mu);
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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] = 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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ecc_del_point(M[j]);
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}
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mp_clear(&mu);
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return MEMORY_E;
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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 = ecc_new_point();
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if (tG == NULL)
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err = MEMORY_E;
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/* tG = G and convert to montgomery */
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if (err == MP_OKAY) {
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err = mp_mulmod(&G->x, &mu, modulus, &tG->x);
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if (err == MP_OKAY)
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err = mp_mulmod(&G->y, &mu, modulus, &tG->y);
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if (err == MP_OKAY)
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err = mp_mulmod(&G->z, &mu, modulus, &tG->z);
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}
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mp_clear(&mu);
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/* calc the M tab */
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/* M[0] == G */
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if (err == MP_OKAY)
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err = mp_copy(&tG->x, &M[0]->x);
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if (err == MP_OKAY)
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err = mp_copy(&tG->y, &M[0]->y);
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if (err == MP_OKAY)
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err = mp_copy(&tG->z, &M[0]->z);
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/* M[1] == 2G */
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if (err == MP_OKAY)
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err = ecc_projective_dbl_point(tG, M[1], modulus, &mp);
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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 = get_digit_count(k) - 1;
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bitcpy = bitbuf = 0;
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first = 1;
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/* perform ops */
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if (err == MP_OKAY) {
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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 = get_digit(k, digidx);
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bitcnt = (int) 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 >> (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 == MP_OKAY)
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err = ecc_projective_add_point(M[0], M[1], M[2], modulus,
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&mp);
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if (err == MP_OKAY)
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err = ecc_projective_dbl_point(M[1], M[2], modulus, &mp);
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if (err == MP_OKAY)
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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 == MP_OKAY)
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err = ecc_projective_add_point(M[0], M[1], M[2], modulus,
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&mp);
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if (err == MP_OKAY)
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err = ecc_projective_dbl_point(M[1], M[2], modulus, &mp);
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if (err == MP_OKAY)
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continue;
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}
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if (err == MP_OKAY)
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err = ecc_projective_add_point(M[0], M[1], M[i^1], modulus, &mp);
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if (err == MP_OKAY)
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err = ecc_projective_dbl_point(M[i], M[i], modulus, &mp);
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if (err != MP_OKAY)
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break;
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} /* end for */
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}
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/* copy result out */
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if (err == MP_OKAY)
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err = mp_copy(&M[0]->x, &R->x);
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if (err == MP_OKAY)
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err = mp_copy(&M[0]->y, &R->y);
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if (err == MP_OKAY)
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err = mp_copy(&M[0]->z, &R->z);
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/* map R back from projective space */
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if (err == MP_OKAY && map)
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err = ecc_map(R, modulus, &mp);
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/* done */
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mp_clear(&mu);
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ecc_del_point(tG);
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for (i = 0; i < 3; i++) {
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ecc_del_point(M[i]);
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}
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return err;
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}
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#endif /* ECC_TIMING_RESISTANT */
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