2 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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;
67 * Check that p is a safe prime and
68 * if g is 2, 3 or 5, check that it is a suitable generator
70 * for 2, p mod 24 == 11
71 * for 3, p mod 12 == 5
72 * for 5, p mod 10 == 3 or 7
75 int DH_check_ex(const DH *dh)
79 (void)DH_check(dh, &errflags);
81 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
82 DHerr(DH_F_DH_CHECK_EX, DH_R_NOT_SUITABLE_GENERATOR);
83 if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
84 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_Q_NOT_PRIME);
85 if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
86 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_Q_VALUE);
87 if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
88 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_J_VALUE);
89 if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
90 DHerr(DH_F_DH_CHECK_EX, DH_R_UNABLE_TO_CHECK_GENERATOR);
91 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
92 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME);
93 if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
94 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
99 int DH_check(const DH *dh, int *ret)
104 BIGNUM *t1 = NULL, *t2 = NULL;
111 t1 = BN_CTX_get(ctx);
112 t2 = BN_CTX_get(ctx);
117 if (BN_cmp(dh->g, BN_value_one()) <= 0)
118 *ret |= DH_NOT_SUITABLE_GENERATOR;
119 else if (BN_cmp(dh->g, dh->p) >= 0)
120 *ret |= DH_NOT_SUITABLE_GENERATOR;
122 /* Check g^q == 1 mod p */
123 if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
126 *ret |= DH_NOT_SUITABLE_GENERATOR;
128 r = BN_is_prime_ex(dh->q, BN_prime_checks, ctx, NULL);
132 *ret |= DH_CHECK_Q_NOT_PRIME;
133 /* Check p == 1 mod q i.e. q divides p - 1 */
134 if (!BN_div(t1, t2, dh->p, dh->q, ctx))
137 *ret |= DH_CHECK_INVALID_Q_VALUE;
138 if (dh->j && BN_cmp(dh->j, t1))
139 *ret |= DH_CHECK_INVALID_J_VALUE;
141 } else if (BN_is_word(dh->g, DH_GENERATOR_2)) {
142 l = BN_mod_word(dh->p, 24);
143 if (l == (BN_ULONG)-1)
146 *ret |= DH_NOT_SUITABLE_GENERATOR;
147 } else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
148 l = BN_mod_word(dh->p, 10);
149 if (l == (BN_ULONG)-1)
151 if ((l != 3) && (l != 7))
152 *ret |= DH_NOT_SUITABLE_GENERATOR;
154 *ret |= DH_UNABLE_TO_CHECK_GENERATOR;
156 r = BN_is_prime_ex(dh->p, BN_prime_checks, ctx, NULL);
160 *ret |= DH_CHECK_P_NOT_PRIME;
162 if (!BN_rshift1(t1, dh->p))
164 r = BN_is_prime_ex(t1, BN_prime_checks, ctx, NULL);
168 *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
177 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
181 (void)DH_check(dh, &errflags);
183 if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
184 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_SMALL);
185 if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
186 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_LARGE);
187 if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
188 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_INVALID);
190 return errflags == 0;
193 int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
204 tmp = BN_CTX_get(ctx);
205 if (tmp == NULL || !BN_set_word(tmp, 1))
207 if (BN_cmp(pub_key, tmp) <= 0)
208 *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
209 if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
211 if (BN_cmp(pub_key, tmp) >= 0)
212 *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
215 /* Check pub_key^q == 1 mod p */
216 if (!BN_mod_exp(tmp, pub_key, dh->q, dh->p, ctx))
219 *ret |= DH_CHECK_PUBKEY_INVALID;