359 lines
9.2 KiB
C
359 lines
9.2 KiB
C
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/* $OpenBSD: dsa_gen.c,v 1.24 2017/01/21 10:38:29 beck Exp $ */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include <openssl/opensslconf.h> /* To see if OPENSSL_NO_SHA is defined */
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#ifndef OPENSSL_NO_SHA
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <openssl/bn.h>
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#include <openssl/evp.h>
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#include <openssl/sha.h>
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#include "bn_lcl.h"
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#include "dsa_locl.h"
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int
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DSA_generate_parameters_ex(DSA *ret, int bits, const unsigned char *seed_in,
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int seed_len, int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
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{
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if (ret->meth->dsa_paramgen)
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return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
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counter_ret, h_ret, cb);
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else {
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const EVP_MD *evpmd;
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size_t qbits;
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if (bits >= 2048) {
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qbits = 256;
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evpmd = EVP_sha256();
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} else {
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qbits = 160;
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evpmd = EVP_sha1();
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}
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return dsa_builtin_paramgen(ret, bits, qbits, evpmd, seed_in,
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seed_len, NULL, counter_ret, h_ret, cb);
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}
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}
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int
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dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
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const unsigned char *seed_in, size_t seed_len, unsigned char *seed_out,
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int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
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{
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int ok = 0;
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unsigned char seed[SHA256_DIGEST_LENGTH];
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unsigned char md[SHA256_DIGEST_LENGTH];
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unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
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BIGNUM *r0, *W, *X, *c, *test;
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BIGNUM *g = NULL, *q = NULL, *p = NULL;
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BN_MONT_CTX *mont = NULL;
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int i, k, n = 0, m = 0, qsize = qbits >> 3;
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int counter = 0;
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int r = 0;
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BN_CTX *ctx = NULL;
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unsigned int h = 2;
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if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
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qsize != SHA256_DIGEST_LENGTH)
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/* invalid q size */
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return 0;
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if (evpmd == NULL)
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/* use SHA1 as default */
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evpmd = EVP_sha1();
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if (bits < 512)
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bits = 512;
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bits = (bits + 63) / 64 * 64;
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if (seed_len < (size_t)qsize) {
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seed_in = NULL; /* seed buffer too small -- ignore */
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seed_len = 0;
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}
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/*
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* App. 2.2 of FIPS PUB 186 allows larger SEED,
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* but our internal buffers are restricted to 160 bits
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*/
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if (seed_len > (size_t)qsize)
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seed_len = qsize;
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if (seed_in != NULL)
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memcpy(seed, seed_in, seed_len);
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else if (seed_len != 0)
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goto err;
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if ((mont=BN_MONT_CTX_new()) == NULL)
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goto err;
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if ((ctx=BN_CTX_new()) == NULL)
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goto err;
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BN_CTX_start(ctx);
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if ((r0 = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((g = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((W = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((q = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((X = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((c = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((p = BN_CTX_get(ctx)) == NULL)
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goto err;
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if ((test = BN_CTX_get(ctx)) == NULL)
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goto err;
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if (!BN_lshift(test, BN_value_one(), bits - 1))
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goto err;
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for (;;) {
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for (;;) { /* find q */
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int seed_is_random;
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/* step 1 */
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if (!BN_GENCB_call(cb, 0, m++))
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goto err;
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if (seed_len == 0) {
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arc4random_buf(seed, qsize);
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seed_is_random = 1;
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} else {
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seed_is_random = 0;
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/* use random seed if 'seed_in' turns out
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to be bad */
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seed_len = 0;
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}
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memcpy(buf, seed, qsize);
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memcpy(buf2, seed, qsize);
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/* precompute "SEED + 1" for step 7: */
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for (i = qsize - 1; i >= 0; i--) {
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buf[i]++;
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if (buf[i] != 0)
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break;
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}
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/* step 2 */
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if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
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goto err;
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if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
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goto err;
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for (i = 0; i < qsize; i++)
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md[i] ^= buf2[i];
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/* step 3 */
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md[0] |= 0x80;
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md[qsize - 1] |= 0x01;
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if (!BN_bin2bn(md, qsize, q))
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goto err;
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/* step 4 */
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r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
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seed_is_random, cb);
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if (r > 0)
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break;
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if (r != 0)
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goto err;
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/* do a callback call */
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/* step 5 */
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}
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if (!BN_GENCB_call(cb, 2, 0))
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goto err;
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if (!BN_GENCB_call(cb, 3, 0))
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goto err;
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/* step 6 */
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counter = 0;
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/* "offset = 2" */
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n = (bits - 1) / 160;
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for (;;) {
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if (counter != 0 && !BN_GENCB_call(cb, 0, counter))
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goto err;
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/* step 7 */
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BN_zero(W);
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/* now 'buf' contains "SEED + offset - 1" */
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for (k = 0; k <= n; k++) {
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/* obtain "SEED + offset + k" by incrementing: */
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for (i = qsize - 1; i >= 0; i--) {
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buf[i]++;
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if (buf[i] != 0)
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break;
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}
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if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
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NULL))
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goto err;
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/* step 8 */
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if (!BN_bin2bn(md, qsize, r0))
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goto err;
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if (!BN_lshift(r0, r0, (qsize << 3) * k))
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goto err;
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if (!BN_add(W, W, r0))
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goto err;
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}
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/* more of step 8 */
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if (!BN_mask_bits(W, bits - 1))
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goto err;
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if (!BN_copy(X, W))
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goto err;
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if (!BN_add(X, X, test))
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goto err;
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/* step 9 */
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if (!BN_lshift1(r0, q))
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goto err;
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if (!BN_mod_ct(c, X, r0, ctx))
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goto err;
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if (!BN_sub(r0, c, BN_value_one()))
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goto err;
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if (!BN_sub(p, X, r0))
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goto err;
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/* step 10 */
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if (BN_cmp(p, test) >= 0) {
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/* step 11 */
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r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
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ctx, 1, cb);
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if (r > 0)
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goto end; /* found it */
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if (r != 0)
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goto err;
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}
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/* step 13 */
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counter++;
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/* "offset = offset + n + 1" */
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/* step 14 */
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if (counter >= 4096)
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break;
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}
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}
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end:
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if (!BN_GENCB_call(cb, 2, 1))
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goto err;
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/* We now need to generate g */
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/* Set r0=(p-1)/q */
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if (!BN_sub(test, p, BN_value_one()))
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goto err;
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if (!BN_div_ct(r0, NULL, test, q, ctx))
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goto err;
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if (!BN_set_word(test, h))
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goto err;
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if (!BN_MONT_CTX_set(mont, p, ctx))
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goto err;
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for (;;) {
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/* g=test^r0%p */
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if (!BN_mod_exp_mont_ct(g, test, r0, p, ctx, mont))
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goto err;
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if (!BN_is_one(g))
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break;
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if (!BN_add(test, test, BN_value_one()))
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goto err;
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h++;
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}
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if (!BN_GENCB_call(cb, 3, 1))
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goto err;
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ok = 1;
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err:
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if (ok) {
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BN_free(ret->p);
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BN_free(ret->q);
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BN_free(ret->g);
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ret->p = BN_dup(p);
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ret->q = BN_dup(q);
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ret->g = BN_dup(g);
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if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
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ok = 0;
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goto err;
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}
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if (counter_ret != NULL)
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*counter_ret = counter;
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if (h_ret != NULL)
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*h_ret = h;
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if (seed_out != NULL)
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memcpy(seed_out, seed, qsize);
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}
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if (ctx) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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BN_MONT_CTX_free(mont);
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return ok;
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}
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#endif
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