/* crypto/dsa/dsa_gen.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* 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 (tjh@cryptsoft.com).
*
* 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 (eay@cryptsoft.com)"
* 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 (tjh@cryptsoft.com)"
*
* 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.]
*/
#undef GENUINE_DSA
#ifdef GENUINE_DSA
/* Parameter generation follows the original release of FIPS PUB 186,
* Appendix 2.2 (i.e. use SHA as defined in FIPS PUB 180) */
#define HASH EVP_sha()
#else
/* Parameter generation follows the updated Appendix 2.2 for FIPS PUB 186,
* also Appendix 2.2 of FIPS PUB 186-1 (i.e. use SHA as defined in
* FIPS PUB 180-1) */
#define HASH EVP_sha1()
#endif
#include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
#ifndef OPENSSL_NO_SHA
#include <stdio.h>
#include <time.h>
#include "cryptlib.h"
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/rand.h>
#include <openssl/sha.h>
static int dsa_builtin_paramgen(DSA *ret, int bits,
unsigned char *seed_in, int seed_len,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
int DSA_generate_parameters_ex(DSA *ret, int bits,
unsigned char *seed_in, int seed_len,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
{
if(ret->meth->dsa_paramgen)
return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
counter_ret, h_ret, cb);
return dsa_builtin_paramgen(ret, bits, seed_in, seed_len,
counter_ret, h_ret, cb);
}
static int dsa_builtin_paramgen(DSA *ret, int bits,
unsigned char *seed_in, int seed_len,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
{
int ok=0;
unsigned char seed[SHA_DIGEST_LENGTH];
unsigned char md[SHA_DIGEST_LENGTH];
unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
BIGNUM *r0,*W,*X,*c,*test;
BIGNUM *g=NULL,*q=NULL,*p=NULL;
BN_MONT_CTX *mont=NULL;
int k,n=0,i,b,m=0;
int counter=0;
int r=0;
BN_CTX *ctx=NULL;
unsigned int h=2;
if (bits < 512) bits=512;
bits=(bits+63)/64*64;
/* NB: seed_len == 0 is special case: copy generated seed to
* seed_in if it is not NULL.
*/
if (seed_len && (seed_len < 20))
seed_in = NULL; /* seed buffer too small -- ignore */
if (seed_len > 20)
seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
* but our internal buffers are restricted to 160 bits*/
if ((seed_in != NULL) && (seed_len == 20))
{
memcpy(seed,seed_in,seed_len);
/* set seed_in to NULL to avoid it being copied back */
seed_in = NULL;
}
if ((ctx=BN_CTX_new()) == NULL) goto err;
if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
W = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
p = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (!BN_lshift(test,BN_value_one(),bits-1))
goto err;
for (;;)
{
for (;;) /* find q */
{
int seed_is_random;
/* step 1 */
if(!BN_GENCB_call(cb, 0, m++))
goto err;
if (!seed_len)
{
RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH);
seed_is_random = 1;
}
else
{
seed_is_random = 0;
seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
}
memcpy(buf,seed,SHA_DIGEST_LENGTH);
memcpy(buf2,seed,SHA_DIGEST_LENGTH);
/* precompute "SEED + 1" for step 7: */
for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
{
buf[i]++;
if (buf[i] != 0) break;
}
/* step 2 */
EVP_Digest(seed,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
EVP_Digest(buf,SHA_DIGEST_LENGTH,buf2,NULL,HASH, NULL);
for (i=0; i<SHA_DIGEST_LENGTH; i++)
md[i]^=buf2[i];
/* step 3 */
md[0]|=0x80;
md[SHA_DIGEST_LENGTH-1]|=0x01;
if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err;
/* step 4 */
r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
seed_is_random, cb);
if (r > 0)
break;
if (r != 0)
goto err;
/* do a callback call */
/* step 5 */
}
if(!BN_GENCB_call(cb, 2, 0)) goto err;
if(!BN_GENCB_call(cb, 3, 0)) goto err;
/* step 6 */
counter=0;
/* "offset = 2" */
n=(bits-1)/160;
b=(bits-1)-n*160;
for (;;)
{
if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
goto err;
/* step 7 */
BN_zero(W);
/* now 'buf' contains "SEED + offset - 1" */
for (k=0; k<=n; k++)
{
/* obtain "SEED + offset + k" by incrementing: */
for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
{
buf[i]++;
if (buf[i] != 0) break;
}
EVP_Digest(buf,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
/* step 8 */
if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0))
goto err;
if (!BN_lshift(r0,r0,160*k)) goto err;
if (!BN_add(W,W,r0)) goto err;
}
/* more of step 8 */
if (!BN_mask_bits(W,bits-1)) goto err;
if (!BN_copy(X,W)) goto err;
if (!BN_add(X,X,test)) goto err;
/* step 9 */
if (!BN_lshift1(r0,q)) goto err;
if (!BN_mod(c,X,r0,ctx)) goto err;
if (!BN_sub(r0,c,BN_value_one())) goto err;
if (!BN_sub(p,X,r0)) goto err;
/* step 10 */
if (BN_cmp(p,test) >= 0)
{
/* step 11 */
r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
ctx, 1, cb);
if (r > 0)
goto end; /* found it */
if (r != 0)
goto err;
}
/* step 13 */
counter++;
/* "offset = offset + n + 1" */
/* step 14 */
if (counter >= 4096) break;
}
}
end:
if(!BN_GENCB_call(cb, 2, 1))
goto err;
/* We now need to generate g */
/* Set r0=(p-1)/q */
if (!BN_sub(test,p,BN_value_one())) goto err;
if (!BN_div(r0,NULL,test,q,ctx)) goto err;
if (!BN_set_word(test,h)) goto err;
if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
for (;;)
{
/* g=test^r0%p */
if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
if (!BN_is_one(g)) break;
if (!BN_add(test,test,BN_value_one())) goto err;
h++;
}
if(!BN_GENCB_call(cb, 3, 1))
goto err;
ok=1;
err:
if (ok)
{
if(ret->p) BN_free(ret->p);
if(ret->q) BN_free(ret->q);
if(ret->g) BN_free(ret->g);
ret->p=BN_dup(p);
ret->q=BN_dup(q);
ret->g=BN_dup(g);
if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
{
ok=0;
goto err;
}
if (seed_in != NULL) memcpy(seed_in,seed,20);
if (counter_ret != NULL) *counter_ret=counter;
if (h_ret != NULL) *h_ret=h;
}
if(ctx)
{
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
if (mont != NULL) BN_MONT_CTX_free(mont);
return ok;
}
#endif