2 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
11 #include "internal/cryptlib.h"
13 #include "internal/bn_int.h"
15 static int generate_key(DH *dh);
16 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
17 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
18 const BIGNUM *a, const BIGNUM *p,
19 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
20 static int dh_init(DH *dh);
21 static int dh_finish(DH *dh);
23 int DH_generate_key(DH *dh)
25 return dh->meth->generate_key(dh);
28 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
30 return dh->meth->compute_key(key, pub_key, dh);
33 int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
36 rv = dh->meth->compute_key(key, pub_key, dh);
39 pad = BN_num_bytes(dh->p) - rv;
41 memmove(key + pad, key, rv);
47 static DH_METHOD dh_ossl = {
59 const DH_METHOD *DH_OpenSSL(void)
64 static int generate_key(DH *dh)
67 int generate_new_key = 0;
70 BN_MONT_CTX *mont = NULL;
71 BIGNUM *pub_key = NULL, *priv_key = NULL;
77 if (dh->priv_key == NULL) {
78 priv_key = BN_secure_new();
83 priv_key = dh->priv_key;
85 if (dh->pub_key == NULL) {
90 pub_key = dh->pub_key;
92 if (dh->flags & DH_FLAG_CACHE_MONT_P) {
93 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
94 dh->lock, dh->p, ctx);
99 if (generate_new_key) {
102 if (!BN_rand_range(priv_key, dh->q))
105 while (BN_is_zero(priv_key) || BN_is_one(priv_key));
107 /* secret exponent length */
108 l = dh->length ? dh->length : BN_num_bits(dh->p) - 1;
109 if (!BN_rand(priv_key, l, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY))
115 BIGNUM *prk = BN_new();
119 BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
121 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) {
125 /* We MUST free prk before any further use of priv_key */
129 dh->pub_key = pub_key;
130 dh->priv_key = priv_key;
134 DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB);
136 if (pub_key != dh->pub_key)
138 if (priv_key != dh->priv_key)
144 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
147 BN_MONT_CTX *mont = NULL;
152 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
153 DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
161 tmp = BN_CTX_get(ctx);
163 if (dh->priv_key == NULL) {
164 DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE);
168 if (dh->flags & DH_FLAG_CACHE_MONT_P) {
169 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
170 dh->lock, dh->p, ctx);
171 BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
176 if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
177 DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY);
182 meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) {
183 DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
187 ret = BN_bn2bin(tmp, key);
196 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
197 const BIGNUM *a, const BIGNUM *p,
198 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
200 return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
203 static int dh_init(DH *dh)
205 dh->flags |= DH_FLAG_CACHE_MONT_P;
209 static int dh_finish(DH *dh)
211 BN_MONT_CTX_free(dh->method_mont_p);