2 * Copyright 1995-2019 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 if (!DH_check_params(dh, &errflags))
28 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
29 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_CHECK_P_NOT_PRIME);
30 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
31 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_NOT_SUITABLE_GENERATOR);
32 if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
33 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_SMALL);
34 if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
35 DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_LARGE);
40 int DH_check_params(const DH *dh, int *ret)
51 tmp = BN_CTX_get(ctx);
55 if (!BN_is_odd(dh->p))
56 *ret |= DH_CHECK_P_NOT_PRIME;
57 if (BN_is_negative(dh->g) || BN_is_zero(dh->g) || BN_is_one(dh->g))
58 *ret |= DH_NOT_SUITABLE_GENERATOR;
59 if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
61 if (BN_cmp(dh->g, tmp) >= 0)
62 *ret |= DH_NOT_SUITABLE_GENERATOR;
63 if (BN_num_bits(dh->p) < DH_MIN_MODULUS_BITS)
64 *ret |= DH_MODULUS_TOO_SMALL;
65 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS)
66 *ret |= DH_MODULUS_TOO_LARGE;
76 * Check that p is a safe prime and
77 * g is a suitable generator.
79 int DH_check_ex(const DH *dh)
83 if (!DH_check(dh, &errflags))
86 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
87 DHerr(DH_F_DH_CHECK_EX, DH_R_NOT_SUITABLE_GENERATOR);
88 if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
89 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_Q_NOT_PRIME);
90 if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
91 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_Q_VALUE);
92 if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
93 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_J_VALUE);
94 if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
95 DHerr(DH_F_DH_CHECK_EX, DH_R_UNABLE_TO_CHECK_GENERATOR);
96 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
97 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME);
98 if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
99 DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
100 if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
101 DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_SMALL);
102 if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
103 DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_LARGE);
105 return errflags == 0;
108 int DH_check(const DH *dh, int *ret)
112 BIGNUM *t1 = NULL, *t2 = NULL;
114 if (!DH_check_params(dh, ret))
121 t1 = BN_CTX_get(ctx);
122 t2 = BN_CTX_get(ctx);
127 if (BN_cmp(dh->g, BN_value_one()) <= 0)
128 *ret |= DH_NOT_SUITABLE_GENERATOR;
129 else if (BN_cmp(dh->g, dh->p) >= 0)
130 *ret |= DH_NOT_SUITABLE_GENERATOR;
132 /* Check g^q == 1 mod p */
133 if (!BN_mod_exp(t1, dh->g, dh->q, dh->p, ctx))
136 *ret |= DH_NOT_SUITABLE_GENERATOR;
138 r = BN_check_prime(dh->q, ctx, NULL);
142 *ret |= DH_CHECK_Q_NOT_PRIME;
143 /* Check p == 1 mod q i.e. q divides p - 1 */
144 if (!BN_div(t1, t2, dh->p, dh->q, ctx))
147 *ret |= DH_CHECK_INVALID_Q_VALUE;
148 if (dh->j && BN_cmp(dh->j, t1))
149 *ret |= DH_CHECK_INVALID_J_VALUE;
152 r = BN_check_prime(dh->p, ctx, NULL);
156 *ret |= DH_CHECK_P_NOT_PRIME;
158 if (!BN_rshift1(t1, dh->p))
160 r = BN_check_prime(t1, ctx, NULL);
164 *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
173 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
177 if (!DH_check_pub_key(dh, pub_key, &errflags))
180 if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
181 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_SMALL);
182 if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
183 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_LARGE);
184 if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
185 DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_INVALID);
187 return errflags == 0;
190 int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
201 tmp = BN_CTX_get(ctx);
202 if (tmp == NULL || !BN_set_word(tmp, 1))
204 if (BN_cmp(pub_key, tmp) <= 0)
205 *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
206 if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
208 if (BN_cmp(pub_key, tmp) >= 0)
209 *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
212 /* Check pub_key^q == 1 mod p */
213 if (!BN_mod_exp(tmp, pub_key, dh->q, dh->p, ctx))
216 *ret |= DH_CHECK_PUBKEY_INVALID;