diff options
Diffstat (limited to 'crypto/dh/dh_gen.c')
| -rw-r--r-- | crypto/dh/dh_gen.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/crypto/dh/dh_gen.c b/crypto/dh/dh_gen.c new file mode 100644 index 0000000000..ff4f18e1e0 --- /dev/null +++ b/crypto/dh/dh_gen.c @@ -0,0 +1,149 @@ +/* crypto/dh/dh_gen.c */ +/* Copyright (C) 1995-1997 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.] + */ + +#include <stdio.h> +#include "cryptlib.h" +#include "bn.h" +#include "dh.h" + +/* 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 strong 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 strong prime (both p and q are prime), + * this generator function can take a very very long time to run. + */ + +DH *DH_generate_parameters(prime_len,generator,callback) +int prime_len; +int generator; +void (*callback)(P_I_I); + { + BIGNUM *p=NULL,*t1,*t2; + DH *ret=NULL; + int g,ok= -1; + BN_CTX *ctx=NULL; + + ret=DH_new(); + ctx=BN_CTX_new(); + if (ctx == NULL) goto err; + t1=ctx->bn[0]; + t2=ctx->bn[1]; + ctx->tos=2; + + if (generator == DH_GENERATOR_2) + { + BN_set_word(t1,24); + BN_set_word(t2,11); + g=2; + } +#ifdef undef /* does not work for strong primes */ + else if (generator == DH_GENERATOR_3) + { + BN_set_word(t1,12); + BN_set_word(t2,5); + g=3; + } +#endif + else if (generator == DH_GENERATOR_5) + { + BN_set_word(t1,10); + BN_set_word(t2,3); + /* BN_set_word(t3,7); just have to miss + * out on these ones :-( */ + g=5; + } + else + g=generator; + + p=BN_generate_prime(prime_len,1,t1,t2,callback); + if (p == NULL) goto err; + if (callback != NULL) callback(3,0); + ret->p=p; + ret->g=BN_new(); + if (!BN_set_word(ret->g,g)) goto err; + ok=1; +err: + if (ok == -1) + { + DHerr(DH_F_DH_GENERATE_PARAMETERS,ERR_R_BN_LIB); + ok=0; + } + + if (ctx != NULL) BN_CTX_free(ctx); + if (!ok && (ret != NULL)) + { + DH_free(ret); + ret=NULL; + } + return(ret); + } |