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- /* 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
- #define OPENSSL_FIPSAPI
- #include <stdio.h>
- #include "cryptlib.h"
- #include <openssl/evp.h>
- #include <openssl/bn.h>
- #include <openssl/rand.h>
- #include <openssl/sha.h>
- #ifdef OPENSSL_FIPS
- #include <openssl/fips.h>
- #include <openssl/fips_rand.h>
- #endif
- #include "dsa_locl.h"
- int DSA_generate_parameters_ex(DSA *ret, int bits,
- const 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);
- else
- {
- const EVP_MD *evpmd;
- size_t qbits = bits >= 2048 ? 256 : 160;
- if (bits >= 2048)
- {
- qbits = 256;
- evpmd = EVP_sha256();
- }
- else
- {
- qbits = 160;
- evpmd = EVP_sha1();
- }
- return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
- seed_in, seed_len, NULL, counter_ret, h_ret, cb);
- }
- }
- int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
- const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
- unsigned char *seed_out,
- int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
- {
- int ok=0;
- unsigned char seed[SHA256_DIGEST_LENGTH];
- unsigned char md[SHA256_DIGEST_LENGTH];
- unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
- BIGNUM *r0,*W,*X,*c,*test;
- BIGNUM *g=NULL,*q=NULL,*p=NULL;
- BN_MONT_CTX *mont=NULL;
- int i, k, n=0, m=0, qsize = qbits >> 3;
- int counter=0;
- int r=0;
- BN_CTX *ctx=NULL;
- unsigned int h=2;
- #ifdef OPENSSL_FIPS
- if(FIPS_selftest_failed())
- {
- FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN, FIPS_R_FIPS_SELFTEST_FAILED);
- goto err;
- }
- if (FIPS_module_mode() && !(ret->flags & DSA_FLAG_NON_FIPS_ALLOW)
- && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
- {
- DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
- goto err;
- }
- #endif
- if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
- qsize != SHA256_DIGEST_LENGTH)
- /* invalid q size */
- return 0;
- if (evpmd == NULL)
- /* use SHA1 as default */
- evpmd = EVP_sha1();
- 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 < (size_t)qsize))
- seed_in = NULL; /* seed buffer too small -- ignore */
- if (seed_len > (size_t)qsize)
- seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
- * but our internal buffers are restricted to 160 bits*/
- if (seed_in != NULL)
- memcpy(seed, seed_in, seed_len);
- 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)
- {
- if (RAND_pseudo_bytes(seed, qsize) < 0)
- goto err;
- 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, qsize);
- memcpy(buf2, seed, qsize);
- /* precompute "SEED + 1" for step 7: */
- for (i = qsize-1; i >= 0; i--)
- {
- buf[i]++;
- if (buf[i] != 0)
- break;
- }
- /* step 2 */
- if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL))
- goto err;
- if (!EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL))
- goto err;
- for (i = 0; i < qsize; i++)
- md[i]^=buf2[i];
- /* step 3 */
- md[0] |= 0x80;
- md[qsize-1] |= 0x01;
- if (!BN_bin2bn(md, qsize, 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;
- 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 = qsize-1; i >= 0; i--)
- {
- buf[i]++;
- if (buf[i] != 0)
- break;
- }
- if (!EVP_Digest(buf, qsize, md ,NULL, evpmd,
- NULL))
- goto err;
- /* step 8 */
- if (!BN_bin2bn(md, qsize, r0))
- goto err;
- if (!BN_lshift(r0,r0,(qsize << 3)*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 (counter_ret != NULL) *counter_ret=counter;
- if (h_ret != NULL) *h_ret=h;
- if (seed_out)
- memcpy(seed_out, seed, qsize);
- }
- if(ctx)
- {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
- if (mont != NULL) BN_MONT_CTX_free(mont);
- return ok;
- }
- #ifdef OPENSSL_FIPS
- /* Security strength of parameter values for (L,N): see FIPS186-3 4.2
- * and SP800-131A
- */
- static int fips_ffc_strength(size_t L, size_t N)
- {
- if (L >= 15360 && N >= 512)
- return 256;
- if (L >= 7680 && N >= 384)
- return 192;
- if (L >= 3072 && N >= 256)
- return 128;
- if (L >= 2048 && N >= 224)
- return 112;
- if (L >= 1024 && N >= 160)
- return 80;
- return 0;
- }
- /* Valid DSA2 parameters from FIPS 186-3 */
- static int dsa2_valid_parameters(size_t L, size_t N)
- {
- if (L == 1024 && N == 160)
- return 80;
- if (L == 2048 && N == 224)
- return 112;
- if (L == 2048 && N == 256)
- return 112;
- if (L == 3072 && N == 256)
- return 128;
- return 0;
- }
- int fips_check_dsa_prng(DSA *dsa, size_t L, size_t N)
- {
- int strength;
- if (!FIPS_module_mode())
- return 1;
- if (dsa->flags & (DSA_FLAG_NON_FIPS_ALLOW|DSA_FLAG_FIPS_CHECKED))
- return 1;
- if (!L || !N)
- {
- L = BN_num_bits(dsa->p);
- N = BN_num_bits(dsa->q);
- }
- if (!dsa2_valid_parameters(L, N))
- {
- FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG, FIPS_R_INVALID_PARAMETERS);
- return 0;
- }
- strength = fips_ffc_strength(L, N);
- if (!strength)
- {
- FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_KEY_TOO_SHORT);
- return 0;
- }
- if (FIPS_rand_strength() >= strength)
- return 1;
- FIPSerr(FIPS_F_FIPS_CHECK_DSA_PRNG,FIPS_R_PRNG_STRENGTH_TOO_LOW);
- return 0;
- }
- #endif /* OPENSSL_FIPS */
- /* This is a parameter generation algorithm for the DSA2 algorithm as
- * described in FIPS 186-3.
- */
- int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
- const EVP_MD *evpmd, const unsigned char *seed_in, size_t seed_len,
- int idx, unsigned char *seed_out,
- int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
- {
- int ok=-1;
- unsigned char *seed = NULL, *seed_tmp = NULL;
- unsigned char md[EVP_MAX_MD_SIZE];
- int mdsize;
- BIGNUM *r0,*W,*X,*c,*test;
- BIGNUM *g=NULL,*q=NULL,*p=NULL;
- BN_MONT_CTX *mont=NULL;
- int i, k, n=0, m=0, qsize = N >> 3;
- int counter=0;
- int r=0;
- BN_CTX *ctx=NULL;
- EVP_MD_CTX mctx;
- unsigned int h=2;
- EVP_MD_CTX_init(&mctx);
- #ifdef OPENSSL_FIPS
- if(FIPS_selftest_failed())
- {
- FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN2,
- FIPS_R_FIPS_SELFTEST_FAILED);
- goto err;
- }
- if (!fips_check_dsa_prng(ret, L, N))
- goto err;
- #endif
- if (evpmd == NULL)
- {
- if (N == 160)
- evpmd = EVP_sha1();
- else if (N == 224)
- evpmd = EVP_sha224();
- else
- evpmd = EVP_sha256();
- }
- mdsize = M_EVP_MD_size(evpmd);
- /* If unverificable g generation only don't need seed */
- if (!ret->p || !ret->q || idx >= 0)
- {
- if (seed_len == 0)
- seed_len = mdsize;
- seed = OPENSSL_malloc(seed_len);
- if (seed_out)
- seed_tmp = seed_out;
- else
- seed_tmp = OPENSSL_malloc(seed_len);
- if (!seed || !seed_tmp)
- goto err;
- if (seed_in)
- memcpy(seed, seed_in, seed_len);
- }
- 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);
- X = BN_CTX_get(ctx);
- c = BN_CTX_get(ctx);
- test = BN_CTX_get(ctx);
- /* if p, q already supplied generate g only */
- if (ret->p && ret->q)
- {
- p = ret->p;
- q = ret->q;
- if (idx >= 0)
- memcpy(seed_tmp, seed, seed_len);
- goto g_only;
- }
- else
- {
- p = BN_CTX_get(ctx);
- q = BN_CTX_get(ctx);
- }
- if (!BN_lshift(test,BN_value_one(),L-1))
- goto err;
- for (;;)
- {
- for (;;) /* find q */
- {
- unsigned char *pmd;
- /* step 1 */
- if(!BN_GENCB_call(cb, 0, m++))
- goto err;
- if (!seed_in)
- {
- if (RAND_pseudo_bytes(seed, seed_len) < 0)
- goto err;
- }
- /* step 2 */
- if (!EVP_Digest(seed, seed_len, md, NULL, evpmd, NULL))
- goto err;
- /* Take least significant bits of md */
- if (mdsize > qsize)
- pmd = md + mdsize - qsize;
- else
- pmd = md;
- if (mdsize < qsize)
- memset(md + mdsize, 0, qsize - mdsize);
- /* step 3 */
- pmd[0] |= 0x80;
- pmd[qsize-1] |= 0x01;
- if (!BN_bin2bn(pmd, qsize, q))
- goto err;
- /* step 4 */
- r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
- seed_in ? 1 : 0, cb);
- if (r > 0)
- break;
- if (r != 0)
- goto err;
- /* Provided seed didn't produce a prime: error */
- if (seed_in)
- {
- ok = 0;
- DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_Q_NOT_PRIME);
- goto err;
- }
- /* do a callback call */
- /* step 5 */
- }
- /* Copy seed to seed_out before we mess with it */
- if (seed_out)
- memcpy(seed_out, seed, seed_len);
- if(!BN_GENCB_call(cb, 2, 0)) goto err;
- if(!BN_GENCB_call(cb, 3, 0)) goto err;
- /* step 6 */
- counter=0;
- /* "offset = 1" */
- n=(L-1)/(mdsize << 3);
- 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 = seed_len-1; i >= 0; i--)
- {
- seed[i]++;
- if (seed[i] != 0)
- break;
- }
- if (!EVP_Digest(seed, seed_len, md ,NULL, evpmd,
- NULL))
- goto err;
- /* step 8 */
- if (!BN_bin2bn(md, mdsize, r0))
- goto err;
- if (!BN_lshift(r0,r0,(mdsize << 3)*k)) goto err;
- if (!BN_add(W,W,r0)) goto err;
- }
- /* more of step 8 */
- if (!BN_mask_bits(W,L-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 >= (int)(4 * L)) break;
- }
- if (seed_in)
- {
- ok = 0;
- DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN2, DSA_R_INVALID_PARAMETERS);
- goto err;
- }
- }
- end:
- if(!BN_GENCB_call(cb, 2, 1))
- goto err;
- g_only:
- /* 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 (idx < 0)
- {
- if (!BN_set_word(test,h))
- goto err;
- }
- else
- h = 1;
- if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
- for (;;)
- {
- __fips_constseg
- static const unsigned char ggen[4] = {0x67,0x67,0x65,0x6e};
- if (idx >= 0)
- {
- md[0] = idx & 0xff;
- md[1] = (h >> 8) & 0xff;
- md[2] = h & 0xff;
- if (!EVP_DigestInit_ex(&mctx, evpmd, NULL))
- goto err;
- if (!EVP_DigestUpdate(&mctx, seed_tmp, seed_len))
- goto err;
- if (!EVP_DigestUpdate(&mctx, ggen, sizeof(ggen)))
- goto err;
- if (!EVP_DigestUpdate(&mctx, md, 3))
- goto err;
- if (!EVP_DigestFinal_ex(&mctx, md, NULL))
- goto err;
- if (!BN_bin2bn(md, mdsize, test))
- goto err;
- }
- /* g=test^r0%p */
- if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
- if (!BN_is_one(g)) break;
- if (idx < 0 && !BN_add(test,test,BN_value_one())) goto err;
- h++;
- if ( idx >= 0 && h > 0xffff)
- goto err;
- }
- if(!BN_GENCB_call(cb, 3, 1))
- goto err;
- ok=1;
- err:
- if (ok == 1)
- {
- if (p != ret->p)
- {
- if(ret->p) BN_free(ret->p);
- ret->p=BN_dup(p);
- }
- if (q != ret->q)
- {
- if(ret->q) BN_free(ret->q);
- ret->q=BN_dup(q);
- }
- if(ret->g) BN_free(ret->g);
- ret->g=BN_dup(g);
- if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
- {
- ok=-1;
- goto err;
- }
- if (counter_ret != NULL) *counter_ret=counter;
- if (h_ret != NULL) *h_ret=h;
- }
- if (seed)
- OPENSSL_free(seed);
- if (seed_out != seed_tmp)
- OPENSSL_free(seed_tmp);
- if(ctx)
- {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
- if (mont != NULL) BN_MONT_CTX_free(mont);
- EVP_MD_CTX_cleanup(&mctx);
- return ok;
- }
- int dsa_paramgen_check_g(DSA *dsa)
- {
- BN_CTX *ctx;
- BIGNUM *tmp;
- BN_MONT_CTX *mont = NULL;
- int rv = -1;
- ctx = BN_CTX_new();
- if (!ctx)
- return -1;
- BN_CTX_start(ctx);
- if (BN_cmp(dsa->g, BN_value_one()) <= 0)
- return 0;
- if (BN_cmp(dsa->g, dsa->p) >= 0)
- return 0;
- tmp = BN_CTX_get(ctx);
- if (!tmp)
- goto err;
- if ((mont=BN_MONT_CTX_new()) == NULL)
- goto err;
- if (!BN_MONT_CTX_set(mont,dsa->p,ctx))
- goto err;
- /* Work out g^q mod p */
- if (!BN_mod_exp_mont(tmp,dsa->g,dsa->q, dsa->p, ctx, mont))
- goto err;
- if (!BN_cmp(tmp, BN_value_one()))
- rv = 1;
- else
- rv = 0;
- err:
- BN_CTX_end(ctx);
- if (mont)
- BN_MONT_CTX_free(mont);
- BN_CTX_free(ctx);
- return rv;
- }
- #endif
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