A local copy of OpenSSL from GitHub
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

#### 130 lines 3.8 KiB Raw Blame History

 `/*` ` * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.` ` *` ` * Licensed under the OpenSSL license (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` ` */` ``` ``` `#include ` `#include "internal/cryptlib.h"` `#include ` `#include "dh_locl.h"` `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 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 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.` ` *` ` * 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.` ` */` `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 (t1 == NULL || 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;` ``` ``` ` 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;` ` } 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 (ctx != NULL) {` ` BN_CTX_end(ctx);` ` BN_CTX_free(ctx);` ` }` ` return ok;` ```} ```