diff options
| author | Emilia Kasper <emilia@openssl.org> | 2015-04-24 15:19:15 +0200 |
|---|---|---|
| committer | Emilia Kasper <emilia@openssl.org> | 2015-04-24 17:35:56 +0200 |
| commit | 7238a82c8ae4dbf9043cb7c253f796615b3277a6 (patch) | |
| tree | 7019b93d6cb0cc5b4adce5d71627dcc5e57adbeb /crypto/ec | |
| parent | 6e5d13076503e9ec7f1c2c690339f99284b7d283 (diff) | |
Correctly set Z_is_one on the return value in the NISTZ256 implementation.
Also add a few comments about constant-timeness.
Thanks to Brian Smith for reporting this issue.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Diffstat (limited to 'crypto/ec')
| -rw-r--r-- | crypto/ec/ecp_nistz256.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/crypto/ec/ecp_nistz256.c b/crypto/ec/ecp_nistz256.c index 2cd6599d85..911c2a6a6a 100644 --- a/crypto/ec/ecp_nistz256.c +++ b/crypto/ec/ecp_nistz256.c @@ -589,6 +589,7 @@ static void ecp_nistz256_windowed_mul(const EC_GROUP *group, for (i = 0; i < num; i++) { P256_POINT *row = table[i]; + /* This is an unusual input, we don't guarantee constant-timeness. */ if ((BN_num_bits(scalar[i]) > 256) || BN_is_negative(scalar[i])) { BIGNUM *mod; @@ -1300,9 +1301,11 @@ static int ecp_nistz256_points_mul(const EC_GROUP *group, memcpy(r->X.d, p.p.X, sizeof(p.p.X)); memcpy(r->Y.d, p.p.Y, sizeof(p.p.Y)); memcpy(r->Z.d, p.p.Z, sizeof(p.p.Z)); + /* Not constant-time, but we're only operating on the public output. */ bn_correct_top(&r->X); bn_correct_top(&r->Y); bn_correct_top(&r->Z); + r->Z_is_one = is_one(p.p.Z); ret = 1; |