A local copy of OpenSSL from GitHub
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/*
* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include <time.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include "dsa_locl.h"
#include <openssl/rand.h>
static int dsa_builtin_keygen(DSA *dsa);
int DSA_generate_key(DSA *dsa)
{
if (dsa->meth->dsa_keygen)
return dsa->meth->dsa_keygen(dsa);
return dsa_builtin_keygen(dsa);
}
static int dsa_builtin_keygen(DSA *dsa)
{
int ok = 0;
BN_CTX *ctx = NULL;
BIGNUM *pub_key = NULL, *priv_key = NULL;
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if (dsa->priv_key == NULL) {
if ((priv_key = BN_secure_new()) == NULL)
goto err;
} else
priv_key = dsa->priv_key;
do
if (!BN_rand_range(priv_key, dsa->q))
goto err;
while (BN_is_zero(priv_key)) ;
if (dsa->pub_key == NULL) {
if ((pub_key = BN_new()) == NULL)
goto err;
} else
pub_key = dsa->pub_key;
{
BIGNUM *local_prk = NULL;
BIGNUM *prk;
if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
local_prk = prk = BN_new();
if (local_prk == NULL)
goto err;
BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
} else {
prk = priv_key;
}
if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {
BN_free(local_prk);
goto err;
}
/* We MUST free local_prk before any further use of priv_key */
BN_free(local_prk);
}
dsa->priv_key = priv_key;
dsa->pub_key = pub_key;
ok = 1;
err:
if (pub_key != dsa->pub_key)
BN_free(pub_key);
if (priv_key != dsa->priv_key)
BN_free(priv_key);
BN_CTX_free(ctx);
return (ok);
}