Added const-time flag to DSA key decoding to avoid potential leak of privkey

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4440)

(cherry picked from commit 6364475a990449ef33fc270ac00472f7210220f2)

diff --git a/crypto/dsa/dsa_ameth.c b/crypto/dsa/dsa_ameth.c
index c4fa105747feb77d1280a363a4ae183b39b33a7a..aac253095141a3917a43cb0c9103ed5346b389d0 100644 (file)
--- a/crypto/dsa/dsa_ameth.c
+++ b/crypto/dsa/dsa_ameth.c
@@ -258,6 +258,7 @@ static int dsa_priv_decode(EVP_PKEY *pkey, PKCS8_PRIV_KEY_INFO *p8)
         goto dsaerr;
     }
 
+    BN_set_flags(dsa->priv_key, BN_FLG_CONSTTIME);
     if (!BN_mod_exp(dsa->pub_key, dsa->g, dsa->priv_key, dsa->p, ctx)) {
         DSAerr(DSA_F_DSA_PRIV_DECODE, DSA_R_BN_ERROR);
         goto dsaerr;