/*

 * 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_local.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_priv_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 *prk = BN_new();

        if (prk == NULL)

            goto err;

        BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);

        if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {

            BN_free(prk);

            goto err;

        }

        /* We MUST free prk before any further use of priv_key */

        BN_free(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;

}