Add secure DSA nonce flag.

[openssl.git] / crypto / dsa / dsa_ossl.c

diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c
index 485cff0b1934ed70be916983dbaef90c64c5c200..d1f80609b1e578f5d8935dcac6846cae54f5b7b0 100644 (file)
--- a/crypto/dsa/dsa_ossl.c
+++ b/crypto/dsa/dsa_ossl.c
@@ -72,7 +72,9 @@
 #endif
 
 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+                         BIGNUM **kinvp, BIGNUM **rp,
+                         const unsigned char *dgst, int dlen);
 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
                         DSA *dsa);
 static int dsa_init(DSA *dsa);
@@ -176,7 +178,8 @@ static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
 redo:
        if ((dsa->kinv == NULL) || (dsa->r == NULL))
                {
-               if (!dsa->meth->dsa_sign_setup(dsa,ctx,&kinv,&r)) goto err;
+               if (!dsa->meth->dsa_sign_setup(dsa,ctx,&kinv,&r,dgst,dlen))
+                       goto err;
                }
        else
                {
@@ -235,7 +238,9 @@ err:
        return(ret);
        }
 
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+                         BIGNUM **kinvp, BIGNUM **rp,
+                         const unsigned char *dgst, int dlen)
        {
        BN_CTX *ctx;
        BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
@@ -261,8 +266,22 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 
        /* Get random k */
        do
-               if (!BN_rand_range(&k, dsa->q)) goto err;
-       while (BN_is_zero(&k));
+               {
+#ifndef OPENSSL_NO_SHA512
+               if (dsa->flags & DSA_FLAG_NONCE_FROM_HASH)
+                       {
+                       /* If DSA_FLAG_NONCE_FROM_HASH is set then we calculate k from
+                        * SHA512(private_key + H(message) + random). This protects the
+                        * private key from a weak PRNG. */
+                       if (!BN_generate_dsa_nonce(&k, dsa->q, dsa->priv_key, dgst,
+                                                  dlen, ctx))
+                               goto err;
+                       }
+               else
+#endif
+                       if (!BN_rand_range(&k, dsa->q)) goto err;
+               } while (BN_is_zero(&k));
+
        if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
                {
                BN_set_flags(&k, BN_FLG_CONSTTIME);