diff options
Diffstat (limited to 'openssl/crypto/dh/dh_gen.c')
| -rw-r--r-- | openssl/crypto/dh/dh_gen.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/openssl/crypto/dh/dh_gen.c b/openssl/crypto/dh/dh_gen.c new file mode 100644 index 000000000..999e1deb4 --- /dev/null +++ b/openssl/crypto/dh/dh_gen.c @@ -0,0 +1,179 @@ +/* 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> + +#ifndef OPENSSL_FIPS + +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) + { + if(ret->meth->generate_params) + return ret->meth->generate_params(ret, prime_len, generator, cb); + 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; + } + +#endif |