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ECC gen z: convert blinding value to Montgomery form before using

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This commit is contained in:
Sean Parkinson
2021-01-07 08:47:55 +10:00
parent 54f072fd8d
commit f955c92008
1 changed files with 29 additions and 2 deletions
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31
wolfcrypt/src/ecc.c
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@ -2626,9 +2626,27 @@ static int ecc_mulmod(mp_int* k, ecc_point* tG, ecc_point* R, ecc_point** M,
static int wc_ecc_gen_z(WC_RNG* rng, int size, ecc_point* p,
mp_int* modulus, mp_digit mp, mp_int* tx, mp_int* ty)
{
int err;
int err = MP_OKAY;
#ifdef WOLFSSL_SMALL_STACK
mp_int* mu = NULL;
#else
mp_int mu[1];
#endif
err = wc_ecc_gen_k(rng, size, ty, modulus);
#ifdef WOLFSSL_SMALL_STACK
mu = (mp_int*)XMALLOC(sizeof(mp_int), NULL, DYNAMIC_TYPE_ECC);
if (mu == NULL)
err = MEMORY_E;
#endif
if (err == MP_OKAY)
err = mp_init(mu);
if (err == MP_OKAY)
err = mp_montgomery_calc_normalization(mu, modulus);
if (err == MP_OKAY)
err = wc_ecc_gen_k(rng, size, ty, modulus);
if (err == MP_OKAY)
err = mp_mulmod(ty, mu, modulus, ty);
if (err == MP_OKAY)
err = mp_mul(p->z, ty, p->z);
if (err == MP_OKAY)
@ -2650,6 +2668,15 @@ static int wc_ecc_gen_z(WC_RNG* rng, int size, ecc_point* p,
if (err == MP_OKAY)
err = mp_montgomery_reduce(p->y, modulus, mp);
#ifdef WOLFSSL_SMALL_STACK
if (mu != NULL) {
mp_clear(mu);
XFREE(mu, NULL, DYNAMIC_TYPE_ECC);
}
#else
mp_clear(mu);
#endif
return err;
}