diff options
| author | Bodo Möller <bodo@openssl.org> | 2005-05-16 01:43:31 +0000 |
|---|---|---|
| committer | Bodo Möller <bodo@openssl.org> | 2005-05-16 01:43:31 +0000 |
| commit | 46a643763de6d8e39ecf6f76fa79b4d04885aa59 (patch) | |
| tree | e1f3cfc98bddba797b5300977dbf3223f008fc4a /crypto/dsa/dsa_key.c | |
| parent | 92c44685724c0d993ea8920577680f3c0a1d79c8 (diff) | |
| download | openssl-46a643763de6d8e39ecf6f76fa79b4d04885aa59.tar.gz | |
Implement fixed-window exponentiation to mitigate hyper-threading
timing attacks.
BN_FLG_EXP_CONSTTIME requests this algorithm, and this done by default for
RSA/DSA/DH private key computations unless
RSA_FLAG_NO_EXP_CONSTTIME/DSA_FLAG_NO_EXP_CONSTTIME/
DH_FLAG_NO_EXP_CONSTTIME is set.
Submitted by: Matthew D Wood
Reviewed by: Bodo Moeller
Diffstat (limited to 'crypto/dsa/dsa_key.c')
| -rw-r--r-- | crypto/dsa/dsa_key.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/crypto/dsa/dsa_key.c b/crypto/dsa/dsa_key.c index 8427b77970..5ba885e1e2 100644 --- a/crypto/dsa/dsa_key.c +++ b/crypto/dsa/dsa_key.c @@ -98,8 +98,21 @@ static int dsa_builtin_keygen(DSA *dsa) } else pub_key=dsa->pub_key; + + { + BIGNUM local_prk; + BIGNUM *prk; + + if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) + { + prk = &local_prk; + BN_with_flags(prk, priv_key, BN_FLG_EXP_CONSTTIME); + } + else + prk = priv_key; - if (!BN_mod_exp(pub_key,dsa->g,priv_key,dsa->p,ctx)) goto err; + if (!BN_mod_exp(pub_key,dsa->g,prk,dsa->p,ctx)) goto err; + } dsa->priv_key=priv_key; dsa->pub_key=pub_key; |