X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fdh%2Fdh_gen.c;h=bbf774f1383f78c170620ff63200cd51114bc890;hp=a929a0f0648000ab0e80d7ad444b9842ce113260;hb=a38c878c2e5e05016bc9faa8d0828eb96efba1c2;hpb=e9224c717711eefb30038c9b37c69795dda93c9a diff --git a/crypto/dh/dh_gen.c b/crypto/dh/dh_gen.c index a929a0f064..bbf774f138 100644 --- a/crypto/dh/dh_gen.c +++ b/crypto/dh/dh_gen.c @@ -1,166 +1,124 @@ -/* crypto/dh/dh_gen.c */ -/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) - * All rights reserved. +/* + * Copyright 1995-2019 The OpenSSL Project Authors. 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.] + * Licensed under the Apache License 2.0 (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html */ -/* NB: These functions have been upgraded - the previous prototypes are in - * dh_depr.c as wrappers to these ones. - * - Geoff +/* + * NB: These functions have been upgraded - the previous prototypes are in + * dh_depr.c as wrappers to these ones. - Geoff */ #include -#include "cryptlib.h" +#include "internal/cryptlib.h" #include -#include +#include "dh_locl.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. +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 p which is prime_len bits long, + * where q=(p-1)/2 is also prime. + * In the following we assume that g is not 0, 1 or p-1, since it + * would generate only trivial subgroups. + * For this case, g is a generator of the order-q subgroup if + * g^q mod p == 1. + * Or in terms of the Legendre symbol: (g/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 for the pointers about the - * special generators and for answering some of my questions. + * Using the quadratic reciprocity law it is possible to solve + * (g/p) == 1 for the special values 2, 3, 5: + * (2/p) == 1 if p mod 8 == 1 or 7. + * (3/p) == 1 if p mod 12 == 1 or 11. + * (5/p) == 1 if p mod 5 == 1 or 4. + * See for instance: https://en.wikipedia.org/wiki/Legendre_symbol * - * 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. + * Since all safe primes > 7 must satisfy p mod 12 == 11 + * and all safe primes > 11 must satisfy p mod 5 != 1 + * we can further improve the condition for g = 2, 3 and 5: + * for 2, p mod 24 == 23 + * for 3, p mod 12 == 11 + * for 5, p mod 60 == 59 */ -/* 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. - */ -int DH_generate_parameters_ex(DH *ret, int prime_len, int generator, BN_GENCB *cb) - { - BIGNUM *t1,*t2; - int g,ok= -1; - BN_CTX *ctx=NULL; +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 (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; - 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; + 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, 23)) + goto err; + g = 2; + } else if (generator == DH_GENERATOR_5) { + if (!BN_set_word(t1, 60)) + goto err; + if (!BN_set_word(t2, 59)) + goto err; + 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, 12)) + goto err; + if (!BN_set_word(t2, 11)) + goto err; + g = generator; + } - /* 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_GENERATE_PARAMETERS, 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_GENERATE_PARAMETERS,ERR_R_BN_LIB); - ok=0; - } + 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; - } + BN_CTX_end(ctx); + BN_CTX_free(ctx); + return ok; +}