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Move computation of synthetic nonces to a dedicated function

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for clarity
This commit is contained in:
Frank Denis
2017-10-06 22:01:06 +02:00
parent 067cd6749d
commit 90f5b55a0a
1 changed files with 34 additions and 24 deletions
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src/libsodium/crypto_sign/ed25519/ref10/sign.c
+34 -24
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@@ -32,6 +32,38 @@ _crypto_sign_ed25519_clamp(unsigned char k[32])
k[31] |= 64;
}
#ifdef ED25519_NONDETERMINISTIC
/* r = hash(B || empty_labelset || Z || pad1 || k || pad2 || empty_labelset || K || extra || M) (mod q) */
static void
_crypto_sign_ed25519_synthetic_r_hv(crypto_hash_sha512_state *hs,
unsigned char nonce[64],
unsigned char sk_copy[64],
const unsigned char sk[64])
{
static const unsigned char B[32] = {
0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
};
static const unsigned char zeros[16] = { 0x00 };
static const unsigned char empty_labelset[3] = { 0x02, 0x00, 0x00 };
memcpy(sk_copy, sk, 32);
_crypto_sign_ed25519_clamp(sk_copy);
crypto_hash_sha512_update(hs, B, 32);
crypto_hash_sha512_update(hs, empty_labelset, 3);
randombytes_buf(nonce, 32);
crypto_hash_sha512_update(hs, nonce, 32);
crypto_hash_sha512_update(hs, zeros, 16 - (32 + 3 + 32) % 16);
crypto_hash_sha512_update(hs, sk_copy, 32);
/* empty pad2 */
crypto_hash_sha512_update(hs, empty_labelset, 3);
crypto_hash_sha512_update(hs, sk + 32, 32);
/* empty extra */
}
#endif
int
_crypto_sign_ed25519_detached(unsigned char *sig, unsigned long long *siglen_p,
const unsigned char *m, unsigned long long mlen,
@@ -44,30 +76,8 @@ _crypto_sign_ed25519_detached(unsigned char *sig, unsigned long long *siglen_p,
ge_p3 R;
#ifdef ED25519_NONDETERMINISTIC
{
static const unsigned char B[32] = {
0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
};
static const unsigned char zeros[16] = { 0x00 };
static const unsigned char empty_labelset[3] = { 0x02, 0x00, 0x00 };
memcpy(az, sk, 32);
_crypto_sign_ed25519_clamp(az);
_crypto_sign_ed25519_ref10_hinit(&hs, prehashed);
crypto_hash_sha512_update(&hs, B, 32);
crypto_hash_sha512_update(&hs, empty_labelset, 3);
randombytes_buf(nonce, 32);
crypto_hash_sha512_update(&hs, nonce, 32);
crypto_hash_sha512_update(&hs, zeros, 16 - (32 + 3 + 32) % 16);
crypto_hash_sha512_update(&hs, az, 32);
/* empty pad2 */
crypto_hash_sha512_update(&hs, empty_labelset, 3);
crypto_hash_sha512_update(&hs, sk + 32, 32);
/* empty extra */
}
_crypto_sign_ed25519_ref10_hinit(&hs, prehashed);
_crypto_sign_ed25519_synthetic_r_hv(&hs, nonce, az, sk);
#else
crypto_hash_sha512(az, sk, 32);
_crypto_sign_ed25519_clamp(az);