dsa_key.c

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/* crypto/dsa/dsa_key.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson ([email protected]).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young ([email protected])"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson ([email protected])"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <time.h>
#include "cryptlib.h"
#ifndef OPENSSL_NO_SHA
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>

#ifdef OPENSSL_FIPS
#include <openssl/fips.h>
#endif

static int dsa_builtin_keygen(DSA *dsa);

int DSA_generate_key(DSA *dsa)
    {
#ifdef OPENSSL_FIPS
    if (FIPS_mode() && !(dsa->meth->flags & DSA_FLAG_FIPS_METHOD)
            && !(dsa->flags & DSA_FLAG_NON_FIPS_ALLOW))
        {
        DSAerr(DSA_F_DSA_GENERATE_KEY, DSA_R_NON_FIPS_DSA_METHOD);
        return 0;
        }
#endif
    if(dsa->meth->dsa_keygen)
        return dsa->meth->dsa_keygen(dsa);
#ifdef OPENSSL_FIPS
    if (FIPS_mode())
        return FIPS_dsa_generate_key(dsa);
#endif
    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_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;
        BIGNUM *prk;

        if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
            {
            BN_init(&local_prk);
            prk = &local_prk;
            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)) goto err;
    }

    dsa->priv_key=priv_key;
    dsa->pub_key=pub_key;
    ok=1;

err:
    if ((pub_key != NULL) && (dsa->pub_key == NULL)) BN_free(pub_key);
    if ((priv_key != NULL) && (dsa->priv_key == NULL)) BN_free(priv_key);
    if (ctx != NULL) BN_CTX_free(ctx);
    return(ok);
    }
#endif