diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/dh/dh_gen.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/dh/dh_gen.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/dh/dh_gen.c b/openssl-1.1.0h/crypto/dh/dh_gen.c new file mode 100644 index 0000000..27ecb98 --- /dev/null +++ b/openssl-1.1.0h/crypto/dh/dh_gen.c @@ -0,0 +1,130 @@ +/* + * 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 <stdio.h> +#include "internal/cryptlib.h" +#include <openssl/bn.h> +#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 <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. + */ +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; +} |