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Add secure DSA nonce flag.

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This change adds the option to calculate (EC)DSA nonces by hashing the
message and private key along with entropy to avoid leaking the private
key if the PRNG fails.
This commit is contained in:
Adam Langley
2013-01-24 16:27:28 -05:00
committed by Ben Laurie
parent 64a786a292
commit 8a99cb29d1
15 changed files with 201 additions and 30 deletions
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9
crypto/dsa/dsa_sign.c
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@@ -72,5 +72,12 @@ DSA_SIG * DSA_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
int DSA_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
{
return dsa->meth->dsa_sign_setup(dsa, ctx_in, kinvp, rp);
if (dsa->flags & DSA_FLAG_NONCE_FROM_HASH)
{
/* One cannot precompute the DSA nonce if it is required to
* depend on the message. */
DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_NONCE_CANNOT_BE_PRECOMPUTED);
return 0;
}
return dsa->meth->dsa_sign_setup(dsa, ctx_in, kinvp, rp, NULL, 0);
}