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Hardcode numwords in vli_modInv

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This commit is contained in:
Manuel Pégourié-Gonnard 2019-11-04 15:04:20 +01:00
parent 3e20adf533
commit 913534837a
3 changed files with 13 additions and 14 deletions
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8
tinycrypt/ecc_dsa.c
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@ -143,7 +143,7 @@ int uECC_sign_with_k(const uint8_t *private_key, const uint8_t *message_hash,
/* Prevent side channel analysis of uECC_vli_modInv() to determine
bits of k / the private key by premultiplying by a random number */
uECC_vli_modMult(k, k, tmp, curve->n); /* k' = rand * k */
uECC_vli_modInv(k, k, curve->n, num_n_words); /* k = 1 / k' */
uECC_vli_modInv(k, k, curve->n); /* k = 1 / k' */
uECC_vli_modMult(k, k, tmp, curve->n); /* k = 1 / k */
uECC_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
@ -242,7 +242,7 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
}
/* Calculate u1 and u2. */
uECC_vli_modInv(z, s, curve->n, num_n_words); /* z = 1/s */
uECC_vli_modInv(z, s, curve->n); /* z = 1/s */
u1[num_n_words - 1] = 0;
bits2int(u1, message_hash, hash_size, curve);
uECC_vli_modMult(u1, u1, z, curve->n); /* u1 = e/s */
@ -255,7 +255,7 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
uECC_vli_set(ty, curve->G + num_words);
uECC_vli_modSub(z, sum, tx, curve->p); /* z = x2 - x1 */
XYcZ_add(tx, ty, sum, sum + num_words, curve);
uECC_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
uECC_vli_modInv(z, z, curve->p); /* z = 1/z */
apply_z(sum, sum + num_words, z);
/* Use Shamir's trick to calculate u1*G + u2*Q */
@ -289,7 +289,7 @@ int uECC_verify(const uint8_t *public_key, const uint8_t *message_hash,
}
}
uECC_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
uECC_vli_modInv(z, z, curve->p); /* Z = 1/Z */
apply_z(rx, ry, z);
/* v = x1 (mod n) */