diff options
Diffstat (limited to '')
| -rw-r--r-- | freebsd/crypto/openssl/crypto/ecdsa/ecs_ossl.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/freebsd/crypto/openssl/crypto/ecdsa/ecs_ossl.c b/freebsd/crypto/openssl/crypto/ecdsa/ecs_ossl.c index 786ff794..ccc1d30a 100644 --- a/freebsd/crypto/openssl/crypto/ecdsa/ecs_ossl.c +++ b/freebsd/crypto/openssl/crypto/ecdsa/ecs_ossl.c @@ -97,6 +97,7 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, EC_POINT *tmp_point = NULL; const EC_GROUP *group; int ret = 0; + int order_bits; if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL) { ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER); @@ -128,6 +129,13 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, goto err; } + /* Preallocate space */ + order_bits = BN_num_bits(order); + if (!BN_set_bit(k, order_bits) + || !BN_set_bit(r, order_bits) + || !BN_set_bit(X, order_bits)) + goto err; + do { /* get random k */ do @@ -141,13 +149,19 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, /* * 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. + * + * We unconditionally perform both of these additions to prevent a + * small timing information leakage. We then choose the sum that is + * one bit longer than the order. This guarantees the code + * path used in the constant time implementations elsewhere. + * + * TODO: revisit the BN_copy aiming for a memory access agnostic + * conditional copy. */ - - if (!BN_add(k, k, order)) + if (!BN_add(r, k, order) + || !BN_add(X, r, order) + || !BN_copy(k, BN_num_bits(r) > order_bits ? r : X)) goto err; - if (BN_num_bits(k) <= BN_num_bits(order)) - if (!BN_add(k, k, order)) - goto err; /* compute r the x-coordinate of generator * k */ if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) { |