diff options
| author | Nicola Tuveri <nic.tuv@gmail.com> | 2018-08-21 00:50:01 +0300 |
|---|---|---|
| committer | Nicola Tuveri <nic.tuv@gmail.com> | 2018-08-24 18:15:24 +0300 |
| commit | 5eee95a54de6854e60886c8e662a902184b12d04 (patch) | |
| tree | 8f4cb55f90f643d88c63b7d829bd50eac9163831 /crypto | |
| parent | 837017b4748d587912d9d218894644d6ca86721f (diff) | |
Backport #6648 to OpenSSL_1_1_0-stable
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7015)
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/ec/ec_mult.c | 46 |
1 files changed, 24 insertions, 22 deletions
diff --git a/crypto/ec/ec_mult.c b/crypto/ec/ec_mult.c index 56c7767772..71ec910c99 100644 --- a/crypto/ec/ec_mult.c +++ b/crypto/ec/ec_mult.c @@ -382,30 +382,32 @@ int ec_wNAF_mul(const EC_GROUP *group, EC_POINT *r, const BIGNUM *scalar, return EC_POINT_set_to_infinity(group, r); } - /*- - * Handle the common cases where the scalar is secret, enforcing a constant - * time scalar multiplication algorithm. - */ - if ((scalar != NULL) && (num == 0)) { - /*- - * In this case we want to compute scalar * GeneratorPoint: this - * codepath is reached most prominently by (ephemeral) key generation - * of EC cryptosystems (i.e. ECDSA keygen and sign setup, ECDH - * keygen/first half), where the scalar is always secret. This is why - * we ignore if BN_FLG_CONSTTIME is actually set and we always call the - * constant time version. - */ - return ec_mul_consttime(group, r, scalar, NULL, ctx); - } - if ((scalar == NULL) && (num == 1)) { + if (!BN_is_zero(group->order) && !BN_is_zero(group->cofactor)) { /*- - * In this case we want to compute scalar * GenericPoint: this codepath - * is reached most prominently by the second half of ECDH, where the - * secret scalar is multiplied by the peer's public point. To protect - * the secret scalar, we ignore if BN_FLG_CONSTTIME is actually set and - * we always call the constant time version. + * Handle the common cases where the scalar is secret, enforcing a constant + * time scalar multiplication algorithm. */ - return ec_mul_consttime(group, r, scalars[0], points[0], ctx); + if ((scalar != NULL) && (num == 0)) { + /*- + * In this case we want to compute scalar * GeneratorPoint: this + * codepath is reached most prominently by (ephemeral) key generation + * of EC cryptosystems (i.e. ECDSA keygen and sign setup, ECDH + * keygen/first half), where the scalar is always secret. This is why + * we ignore if BN_FLG_CONSTTIME is actually set and we always call the + * constant time version. + */ + return ec_mul_consttime(group, r, scalar, NULL, ctx); + } + if ((scalar == NULL) && (num == 1)) { + /*- + * In this case we want to compute scalar * GenericPoint: this codepath + * is reached most prominently by the second half of ECDH, where the + * secret scalar is multiplied by the peer's public point. To protect + * the secret scalar, we ignore if BN_FLG_CONSTTIME is actually set and + * we always call the constant time version. + */ + return ec_mul_consttime(group, r, scalars[0], points[0], ctx); + } } for (i = 0; i < num; i++) { |