150 lines
5.2 KiB
C
150 lines
5.2 KiB
C
/* 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.]
|
|
*/
|
|
|
|
#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,cb_arg)
|
|
int prime_len;
|
|
int generator;
|
|
void (*callback)(P_I_I_P);
|
|
char *cb_arg;
|
|
{
|
|
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(NULL,prime_len,1,t1,t2,callback,cb_arg);
|
|
if (p == NULL) goto err;
|
|
if (callback != NULL) callback(3,0,cb_arg);
|
|
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);
|
|
}
|