2 * Copyright 1995-2017 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"
12 #include <openssl/bn.h>
16 * Check that p and g are suitable enough
21 int DH_check_params_ex(const DH *dh)
25 (void)DH_check_params(dh, &errflags);
27 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
28 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_CHECK_P_NOT_PRIME);
29 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
30 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_NOT_SUITABLE_GENERATOR);
35 int DH_check_params(const DH *dh, int *ret)
46 tmp = BN_CTX_get(ctx);
50 if (!BN_is_odd(dh->p))
51 *ret |= DH_CHECK_P_NOT_PRIME;
52 if (BN_is_negative(dh->g) || BN_is_zero(dh->g) || BN_is_one(dh->g))
53 *ret |= DH_NOT_SUITABLE_GENERATOR;
54 if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
56 if (BN_cmp(dh->g, tmp) >= 0)
57 *ret |= DH_NOT_SUITABLE_GENERATOR;
69 * Check that p is a safe prime and
70 * if g is 2, 3 or 5, check that it is a suitable generator
72 * for 2, p mod 24 == 11
73 * for 3, p mod 12 == 5
74 * for 5, p mod 10 == 3 or 7
77 int DH_check_ex(const DH *dh)
81 (void)DH_check(dh, &errflags);
83 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
84 DHerr(DH_F_DH_CHECK_EX, DH_R_NOT_SUITABLE_GENERATOR);
85 if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
86 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_Q_NOT_PRIME);
87 if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
88 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_Q_VALUE);
89 if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
90 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_J_VALUE);
91 if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
92 DHerr(DH_F_DH_CHECK_EX, DH_R_UNABLE_TO_CHECK_GENERATOR);
93 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
94 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME);
95 if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
96 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
101 int DH_check(const DH *dh, int *ret)
106 BIGNUM *t1 = NULL, *t2 = NULL;
113 t1 = BN_CTX_get(ctx);
114 t2 = BN_CTX_get(ctx);
119 if (BN_cmp(dh->g, BN_value_one()) <= 0)
120 *ret |= DH_NOT_SUITABLE_GENERATOR;
121 else if (BN_cmp(dh->g, dh->p) >= 0)
122 *ret |= DH_NOT_SUITABLE_GENERATOR;
124 /* Check g^q == 1 mod p */
125 if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
128 *ret |= DH_NOT_SUITABLE_GENERATOR;
130 r = BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL);
134 *ret |= DH_CHECK_Q_NOT_PRIME;
135 /* Check p == 1 mod q i.e. q divides p - 1 */
136 if (!BN_div(t1, t2, dh->p, dh->q, ctx))
139 *ret |= DH_CHECK_INVALID_Q_VALUE;
140 if (dh->j && BN_cmp(dh->j, t1))
141 *ret |= DH_CHECK_INVALID_J_VALUE;
143 } else if (BN_is_word(dh->g, DH_GENERATOR_2)) {
144 l = BN_mod_word(dh->p, 24);
145 if (l == (BN_ULONG)-1)
148 *ret |= DH_NOT_SUITABLE_GENERATOR;
149 } else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
150 l = BN_mod_word(dh->p, 10);
151 if (l == (BN_ULONG)-1)
153 if ((l != 3) && (l != 7))
154 *ret |= DH_NOT_SUITABLE_GENERATOR;
156 *ret |= DH_UNABLE_TO_CHECK_GENERATOR;
158 r = BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL);
162 *ret |= DH_CHECK_P_NOT_PRIME;
164 if (!BN_rshift1(t1, dh->p))
166 r = BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL);
170 *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
181 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
185 (void)DH_check(dh, &errflags);
187 if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
188 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_SMALL);
189 if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
190 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_LARGE);
191 if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
192 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_INVALID);
194 return errflags == 0;
197 int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
208 tmp = BN_CTX_get(ctx);
209 if (tmp == NULL || !BN_set_word(tmp, 1))
211 if (BN_cmp(pub_key, tmp) <= 0)
212 *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
213 if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
215 if (BN_cmp(pub_key, tmp) >= 0)
216 *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
219 /* Check pub_key^q == 1 mod p */
220 if (!BN_mod_exp(tmp, pub_key, dh->q, dh->p, ctx))
223 *ret |= DH_CHECK_PUBKEY_INVALID;