Fix a SCA leak in BN_generate_dsa_nonce
@@ -264,8 +264,7 @@ int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range,
goto err;
/* We copy |priv| into a local buffer to avoid exposing its length. */
- todo = sizeof(priv->d[0]) * priv->top;
- if (todo > sizeof(private_bytes)) {
+ if (BN_bn2binpad(priv, private_bytes, sizeof(private_bytes)) < 0) {
/*
* No reasonable DSA or ECDSA key should have a private key this
* large and we don't handle this case in order to avoid leaking the
@@ -274,8 +273,6 @@ int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range,
BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE);
goto err;
}
- memcpy(private_bytes, priv->d, todo);
- memset(private_bytes + todo, 0, sizeof(private_bytes) - todo);
md = EVP_MD_fetch(libctx, "SHA512", NULL);
if (md == NULL) {
