--- /dev/null
+/* crypto/dh/dh_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.]
+ */
+
+/* NB: These functions have been upgraded - the previous prototypes are in
+ * dh_depr.c as wrappers to these ones.
+ * - Geoff
+ */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include <openssl/bn.h>
+#include <openssl/dh.h>
+
+#ifdef OPENSSL_FIPS
+#include <openssl/fips.h>
+#endif
+
+static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB *cb);
+
+int DH_generate_parameters_ex(DH *ret, int prime_len, int generator, BN_GENCB *cb)
+ {
+#ifdef OPENSSL_FIPS
+ if (FIPS_mode() && !(ret->meth->flags & DH_FLAG_FIPS_METHOD)
+ && !(ret->flags & DH_FLAG_NON_FIPS_ALLOW))
+ {
+ DHerr(DH_F_DH_GENERATE_PARAMETERS_EX, DH_R_NON_FIPS_METHOD);
+ return 0;
+ }
+#endif
+ if(ret->meth->generate_params)
+ return ret->meth->generate_params(ret, prime_len, generator, cb);
+#ifdef OPENSSL_FIPS
+ if (FIPS_mode())
+ return FIPS_dh_generate_parameters_ex(ret, prime_len,
+ generator, cb);
+#endif
+ return dh_builtin_genparams(ret, prime_len, generator, cb);
+ }
+
+/* We generate DH parameters as follows
+ * find a prime q which is prime_len/2 bits long.
+ * p=(2*q)+1 or (p-1)/2 = q
+ * For this case, g is a generator if
+ * g^((p-1)/q) mod p != 1 for values of q which are the factors of p-1.
+ * Since the factors of p-1 are q and 2, we just need to check
+ * g^2 mod p != 1 and g^q mod p != 1.
+ *
+ * Having said all that,
+ * there is another special case method for the generators 2, 3 and 5.
+ * for 2, p mod 24 == 11
+ * for 3, p mod 12 == 5 <<<<< does not work for safe primes.
+ * for 5, p mod 10 == 3 or 7
+ *
+ * Thanks to Phil Karn <karn@qualcomm.com> for the pointers about the
+ * special generators and for answering some of my questions.
+ *
+ * I've implemented the second simple method :-).
+ * Since DH should be using a safe prime (both p and q are prime),
+ * this generator function can take a very very long time to run.
+ */
+/* Actually there is no reason to insist that 'generator' be a generator.
+ * It's just as OK (and in some sense better) to use a generator of the
+ * order-q subgroup.
+ */
+static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB *cb)
+ {
+ BIGNUM *t1,*t2;
+ int g,ok= -1;
+ BN_CTX *ctx=NULL;
+
+ ctx=BN_CTX_new();
+ if (ctx == NULL) goto err;
+ BN_CTX_start(ctx);
+ t1 = BN_CTX_get(ctx);
+ t2 = BN_CTX_get(ctx);
+ if (t1 == NULL || t2 == NULL) goto err;
+
+ /* Make sure 'ret' has the necessary elements */
+ if(!ret->p && ((ret->p = BN_new()) == NULL)) goto err;
+ if(!ret->g && ((ret->g = BN_new()) == NULL)) goto err;
+
+ if (generator <= 1)
+ {
+ DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_BAD_GENERATOR);
+ goto err;
+ }
+ if (generator == DH_GENERATOR_2)
+ {
+ if (!BN_set_word(t1,24)) goto err;
+ if (!BN_set_word(t2,11)) goto err;
+ g=2;
+ }
+#if 0 /* does not work for safe primes */
+ else if (generator == DH_GENERATOR_3)
+ {
+ if (!BN_set_word(t1,12)) goto err;
+ if (!BN_set_word(t2,5)) goto err;
+ g=3;
+ }
+#endif
+ else if (generator == DH_GENERATOR_5)
+ {
+ if (!BN_set_word(t1,10)) goto err;
+ if (!BN_set_word(t2,3)) goto err;
+ /* BN_set_word(t3,7); just have to miss
+ * out on these ones :-( */
+ g=5;
+ }
+ else
+ {
+ /* in the general case, don't worry if 'generator' is a
+ * generator or not: since we are using safe primes,
+ * it will generate either an order-q or an order-2q group,
+ * which both is OK */
+ if (!BN_set_word(t1,2)) goto err;
+ if (!BN_set_word(t2,1)) goto err;
+ g=generator;
+ }
+
+ if(!BN_generate_prime_ex(ret->p,prime_len,1,t1,t2,cb)) goto err;
+ if(!BN_GENCB_call(cb, 3, 0)) goto err;
+ if (!BN_set_word(ret->g,g)) goto err;
+ ok=1;
+err:
+ if (ok == -1)
+ {
+ DHerr(DH_F_DH_BUILTIN_GENPARAMS,ERR_R_BN_LIB);
+ ok=0;
+ }
+
+ if (ctx != NULL)
+ {
+ BN_CTX_end(ctx);
+ BN_CTX_free(ctx);
+ }
+ return ok;
+ }
projects / cassiopeia.git / blobdiff