-/* 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 <stdio.h>
-#include "cryptlib.h"
+#include "internal/cryptlib.h"
#include <openssl/bn.h>
-#include <openssl/dh.h>
-#ifdef OPENSSL_FIPS
-#include <openssl/fips.h>
-#endif
+#include "dh_locl.h"
-static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB *cb);
+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);
- }
+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.
+/*-
+ * 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
+ * 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
*
- * 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.
+ * 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
*/
-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;
+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;
-#ifdef OPENSSL_FIPS
- if(FIPS_selftest_failed())
- {
- FIPSerr(FIPS_F_DH_BUILTIN_GENPARAMS,FIPS_R_FIPS_SELFTEST_FAILED);
- return 0;
- }
+ 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;
- if (FIPS_mode() && (prime_len < OPENSSL_DH_FIPS_MIN_MODULUS_BITS))
- {
- DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_KEY_SIZE_TOO_SMALL);
- goto err;
- }
-#endif
+ /* 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_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 (!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;
+}
projects / openssl.git / blobdiff