diff options
| -rw-r--r-- | CHANGES | 7 | ||||
| -rw-r--r-- | crypto/ecdsa/ecs_ossl.c | 10 |
2 files changed, 17 insertions, 0 deletions
@@ -4,6 +4,13 @@ Changes between 1.0.0d and 1.0.1 [xx XXX xxxx] + *) Add protection against ECDSA timing attacks as mentioned in the paper + by Billy Bob Brumley and Nicola Tuveri, see: + + http://eprint.iacr.org/2011/232.pdf + + [Billy Bob Brumley and Nicola Tuveri] + *) Add TLS v1.2 server support for client authentication. [Steve Henson] diff --git a/crypto/ecdsa/ecs_ossl.c b/crypto/ecdsa/ecs_ossl.c index 551cf5068f..bbb5588cbe 100644 --- a/crypto/ecdsa/ecs_ossl.c +++ b/crypto/ecdsa/ecs_ossl.c @@ -144,6 +144,16 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, } while (BN_is_zero(k)); +#ifdef ECDSA_POINT_MUL_NO_CONSTTIME + /* We do not want timing information to leak the length of k, + * so we compute G*k using an equivalent scalar of fixed + * bit-length. */ + + if (!BN_add(k, k, order)) goto err; + if (BN_num_bits(k) <= BN_num_bits(order)) + if (!BN_add(k, k, order)) goto err; +#endif /* def(ECDSA_POINT_MUL_NO_CONSTTIME) */ + /* compute r the x-coordinate of generator * k */ if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) { |