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| 1 /* crypto/dh/dh_gen.c */ | |
| 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) | |
| 3 * All rights reserved. | |
| 4 * | |
| 5 * This package is an SSL implementation written | |
| 6 * by Eric Young (eay@cryptsoft.com). | |
| 7 * The implementation was written so as to conform with Netscapes SSL. | |
| 8 * | |
| 9 * This library is free for commercial and non-commercial use as long as | |
| 10 * the following conditions are aheared to. The following conditions | |
| 11 * apply to all code found in this distribution, be it the RC4, RSA, | |
| 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
| 13 * included with this distribution is covered by the same copyright terms | |
| 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
| 15 * | |
| 16 * Copyright remains Eric Young's, and as such any Copyright notices in | |
| 17 * the code are not to be removed. | |
| 18 * If this package is used in a product, Eric Young should be given attribution | |
| 19 * as the author of the parts of the library used. | |
| 20 * This can be in the form of a textual message at program startup or | |
| 21 * in documentation (online or textual) provided with the package. | |
| 22 * | |
| 23 * Redistribution and use in source and binary forms, with or without | |
| 24 * modification, are permitted provided that the following conditions | |
| 25 * are met: | |
| 26 * 1. Redistributions of source code must retain the copyright | |
| 27 * notice, this list of conditions and the following disclaimer. | |
| 28 * 2. Redistributions in binary form must reproduce the above copyright | |
| 29 * notice, this list of conditions and the following disclaimer in the | |
| 30 * documentation and/or other materials provided with the distribution. | |
| 31 * 3. All advertising materials mentioning features or use of this software | |
| 32 * must display the following acknowledgement: | |
| 33 * "This product includes cryptographic software written by | |
| 34 * Eric Young (eay@cryptsoft.com)" | |
| 35 * The word 'cryptographic' can be left out if the rouines from the library | |
| 36 * being used are not cryptographic related :-). | |
| 37 * 4. If you include any Windows specific code (or a derivative thereof) from | |
| 38 * the apps directory (application code) you must include an acknowledgement: | |
| 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
| 40 * | |
| 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND | |
| 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
| 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 51 * SUCH DAMAGE. | |
| 52 * | |
| 53 * The licence and distribution terms for any publically available version or | |
| 54 * derivative of this code cannot be changed. i.e. this code cannot simply be | |
| 55 * copied and put under another distribution licence | |
| 56 * [including the GNU Public Licence.] | |
| 57 */ | |
| 58 | |
| 59 /* NB: These functions have been upgraded - the previous prototypes are in | |
| 60 * dh_depr.c as wrappers to these ones. | |
| 61 * - Geoff | |
| 62 */ | |
| 63 | |
| 64 #include <stdio.h> | |
| 65 #include <openssl/bn.h> | |
| 66 #include <openssl/dh.h> | |
| 67 #include <openssl/err.h> | |
| 68 #include <openssl/fips.h> | |
| 69 | |
| 70 #ifdef OPENSSL_FIPS | |
| 71 | |
| 72 static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB
*cb); | |
| 73 | |
| 74 int DH_generate_parameters_ex(DH *ret, int prime_len, int generator, BN_GENCB *c
b) | |
| 75 { | |
| 76 if(ret->meth->generate_params) | |
| 77 return ret->meth->generate_params(ret, prime_len, generator, cb)
; | |
| 78 return dh_builtin_genparams(ret, prime_len, generator, cb); | |
| 79 } | |
| 80 | |
| 81 /* We generate DH parameters as follows | |
| 82 * find a prime q which is prime_len/2 bits long. | |
| 83 * p=(2*q)+1 or (p-1)/2 = q | |
| 84 * For this case, g is a generator if | |
| 85 * g^((p-1)/q) mod p != 1 for values of q which are the factors of p-1. | |
| 86 * Since the factors of p-1 are q and 2, we just need to check | |
| 87 * g^2 mod p != 1 and g^q mod p != 1. | |
| 88 * | |
| 89 * Having said all that, | |
| 90 * there is another special case method for the generators 2, 3 and 5. | |
| 91 * for 2, p mod 24 == 11 | |
| 92 * for 3, p mod 12 == 5 <<<<< does not work for safe primes. | |
| 93 * for 5, p mod 10 == 3 or 7 | |
| 94 * | |
| 95 * Thanks to Phil Karn <karn@qualcomm.com> for the pointers about the | |
| 96 * special generators and for answering some of my questions. | |
| 97 * | |
| 98 * I've implemented the second simple method :-). | |
| 99 * Since DH should be using a safe prime (both p and q are prime), | |
| 100 * this generator function can take a very very long time to run. | |
| 101 */ | |
| 102 /* Actually there is no reason to insist that 'generator' be a generator. | |
| 103 * It's just as OK (and in some sense better) to use a generator of the | |
| 104 * order-q subgroup. | |
| 105 */ | |
| 106 static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB
*cb) | |
| 107 { | |
| 108 BIGNUM *t1,*t2; | |
| 109 int g,ok= -1; | |
| 110 BN_CTX *ctx=NULL; | |
| 111 | |
| 112 if(FIPS_selftest_failed()) | |
| 113 { | |
| 114 FIPSerr(FIPS_F_DH_BUILTIN_GENPARAMS,FIPS_R_FIPS_SELFTEST_FAILED)
; | |
| 115 return 0; | |
| 116 } | |
| 117 | |
| 118 if (FIPS_mode() && (prime_len < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) | |
| 119 { | |
| 120 DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_KEY_SIZE_TOO_SMALL); | |
| 121 goto err; | |
| 122 } | |
| 123 | |
| 124 ctx=BN_CTX_new(); | |
| 125 if (ctx == NULL) goto err; | |
| 126 BN_CTX_start(ctx); | |
| 127 t1 = BN_CTX_get(ctx); | |
| 128 t2 = BN_CTX_get(ctx); | |
| 129 if (t1 == NULL || t2 == NULL) goto err; | |
| 130 | |
| 131 /* Make sure 'ret' has the necessary elements */ | |
| 132 if(!ret->p && ((ret->p = BN_new()) == NULL)) goto err; | |
| 133 if(!ret->g && ((ret->g = BN_new()) == NULL)) goto err; | |
| 134 | |
| 135 if (generator <= 1) | |
| 136 { | |
| 137 DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_BAD_GENERATOR); | |
| 138 goto err; | |
| 139 } | |
| 140 if (generator == DH_GENERATOR_2) | |
| 141 { | |
| 142 if (!BN_set_word(t1,24)) goto err; | |
| 143 if (!BN_set_word(t2,11)) goto err; | |
| 144 g=2; | |
| 145 } | |
| 146 #if 0 /* does not work for safe primes */ | |
| 147 else if (generator == DH_GENERATOR_3) | |
| 148 { | |
| 149 if (!BN_set_word(t1,12)) goto err; | |
| 150 if (!BN_set_word(t2,5)) goto err; | |
| 151 g=3; | |
| 152 } | |
| 153 #endif | |
| 154 else if (generator == DH_GENERATOR_5) | |
| 155 { | |
| 156 if (!BN_set_word(t1,10)) goto err; | |
| 157 if (!BN_set_word(t2,3)) goto err; | |
| 158 /* BN_set_word(t3,7); just have to miss | |
| 159 * out on these ones :-( */ | |
| 160 g=5; | |
| 161 } | |
| 162 else | |
| 163 { | |
| 164 /* in the general case, don't worry if 'generator' is a | |
| 165 * generator or not: since we are using safe primes, | |
| 166 * it will generate either an order-q or an order-2q group, | |
| 167 * which both is OK */ | |
| 168 if (!BN_set_word(t1,2)) goto err; | |
| 169 if (!BN_set_word(t2,1)) goto err; | |
| 170 g=generator; | |
| 171 } | |
| 172 | |
| 173 if(!BN_generate_prime_ex(ret->p,prime_len,1,t1,t2,cb)) goto err; | |
| 174 if(!BN_GENCB_call(cb, 3, 0)) goto err; | |
| 175 if (!BN_set_word(ret->g,g)) goto err; | |
| 176 ok=1; | |
| 177 err: | |
| 178 if (ok == -1) | |
| 179 { | |
| 180 DHerr(DH_F_DH_BUILTIN_GENPARAMS,ERR_R_BN_LIB); | |
| 181 ok=0; | |
| 182 } | |
| 183 | |
| 184 if (ctx != NULL) | |
| 185 { | |
| 186 BN_CTX_end(ctx); | |
| 187 BN_CTX_free(ctx); | |
| 188 } | |
| 189 return ok; | |
| 190 } | |
| 191 | |
| 192 #endif | |
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