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>
15 # define DH_NUMBER_ITERATIONS_FOR_PRIME 64
18 * Check that p and g are suitable enough
23 int DH_check_params_ex(const DH
*dh
)
27 if (!DH_check_params(dh
, &errflags
))
30 if ((errflags
& DH_CHECK_P_NOT_PRIME
) != 0)
31 DHerr(DH_F_DH_CHECK_PARAMS_EX
, DH_R_CHECK_P_NOT_PRIME
);
32 if ((errflags
& DH_NOT_SUITABLE_GENERATOR
) != 0)
33 DHerr(DH_F_DH_CHECK_PARAMS_EX
, DH_R_NOT_SUITABLE_GENERATOR
);
34 if ((errflags
& DH_MODULUS_TOO_SMALL
) != 0)
35 DHerr(DH_F_DH_CHECK_PARAMS_EX
, DH_R_MODULUS_TOO_SMALL
);
36 if ((errflags
& DH_MODULUS_TOO_LARGE
) != 0)
37 DHerr(DH_F_DH_CHECK_PARAMS_EX
, DH_R_MODULUS_TOO_LARGE
);
42 int DH_check_params(const DH
*dh
, int *ret
)
53 tmp
= BN_CTX_get(ctx
);
57 if (!BN_is_odd(dh
->p
))
58 *ret
|= DH_CHECK_P_NOT_PRIME
;
59 if (BN_is_negative(dh
->g
) || BN_is_zero(dh
->g
) || BN_is_one(dh
->g
))
60 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
61 if (BN_copy(tmp
, dh
->p
) == NULL
|| !BN_sub_word(tmp
, 1))
63 if (BN_cmp(dh
->g
, tmp
) >= 0)
64 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
65 if (BN_num_bits(dh
->p
) < DH_MIN_MODULUS_BITS
)
66 *ret
|= DH_MODULUS_TOO_SMALL
;
67 if (BN_num_bits(dh
->p
) > OPENSSL_DH_MAX_MODULUS_BITS
)
68 *ret
|= DH_MODULUS_TOO_LARGE
;
78 * Check that p is a safe prime and
79 * g is a suitable generator.
81 int DH_check_ex(const DH
*dh
)
85 if (!DH_check(dh
, &errflags
))
88 if ((errflags
& DH_NOT_SUITABLE_GENERATOR
) != 0)
89 DHerr(DH_F_DH_CHECK_EX
, DH_R_NOT_SUITABLE_GENERATOR
);
90 if ((errflags
& DH_CHECK_Q_NOT_PRIME
) != 0)
91 DHerr(DH_F_DH_CHECK_EX
, DH_R_CHECK_Q_NOT_PRIME
);
92 if ((errflags
& DH_CHECK_INVALID_Q_VALUE
) != 0)
93 DHerr(DH_F_DH_CHECK_EX
, DH_R_CHECK_INVALID_Q_VALUE
);
94 if ((errflags
& DH_CHECK_INVALID_J_VALUE
) != 0)
95 DHerr(DH_F_DH_CHECK_EX
, DH_R_CHECK_INVALID_J_VALUE
);
96 if ((errflags
& DH_UNABLE_TO_CHECK_GENERATOR
) != 0)
97 DHerr(DH_F_DH_CHECK_EX
, DH_R_UNABLE_TO_CHECK_GENERATOR
);
98 if ((errflags
& DH_CHECK_P_NOT_PRIME
) != 0)
99 DHerr(DH_F_DH_CHECK_EX
, DH_R_CHECK_P_NOT_PRIME
);
100 if ((errflags
& DH_CHECK_P_NOT_SAFE_PRIME
) != 0)
101 DHerr(DH_F_DH_CHECK_EX
, DH_R_CHECK_P_NOT_SAFE_PRIME
);
102 if ((errflags
& DH_MODULUS_TOO_SMALL
) != 0)
103 DHerr(DH_F_DH_CHECK_EX
, DH_R_MODULUS_TOO_SMALL
);
104 if ((errflags
& DH_MODULUS_TOO_LARGE
) != 0)
105 DHerr(DH_F_DH_CHECK_EX
, DH_R_MODULUS_TOO_LARGE
);
107 return errflags
== 0;
110 int DH_check(const DH
*dh
, int *ret
)
114 BIGNUM
*t1
= NULL
, *t2
= NULL
;
116 if (!DH_check_params(dh
, ret
))
123 t1
= BN_CTX_get(ctx
);
124 t2
= BN_CTX_get(ctx
);
129 if (BN_cmp(dh
->g
, BN_value_one()) <= 0)
130 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
131 else if (BN_cmp(dh
->g
, dh
->p
) >= 0)
132 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
134 /* Check g^q == 1 mod p */
135 if (!BN_mod_exp(t1
, dh
->g
, dh
->q
, dh
->p
, ctx
))
138 *ret
|= DH_NOT_SUITABLE_GENERATOR
;
140 r
= BN_is_prime_ex(dh
->q
, DH_NUMBER_ITERATIONS_FOR_PRIME
, ctx
, NULL
);
144 *ret
|= DH_CHECK_Q_NOT_PRIME
;
145 /* Check p == 1 mod q i.e. q divides p - 1 */
146 if (!BN_div(t1
, t2
, dh
->p
, dh
->q
, ctx
))
149 *ret
|= DH_CHECK_INVALID_Q_VALUE
;
150 if (dh
->j
&& BN_cmp(dh
->j
, t1
))
151 *ret
|= DH_CHECK_INVALID_J_VALUE
;
154 r
= BN_is_prime_ex(dh
->p
, DH_NUMBER_ITERATIONS_FOR_PRIME
, ctx
, NULL
);
158 *ret
|= DH_CHECK_P_NOT_PRIME
;
160 if (!BN_rshift1(t1
, dh
->p
))
162 r
= BN_is_prime_ex(t1
, DH_NUMBER_ITERATIONS_FOR_PRIME
, ctx
, NULL
);
166 *ret
|= DH_CHECK_P_NOT_SAFE_PRIME
;
175 int DH_check_pub_key_ex(const DH
*dh
, const BIGNUM
*pub_key
)
179 (void)DH_check(dh
, &errflags
);
181 if ((errflags
& DH_CHECK_PUBKEY_TOO_SMALL
) != 0)
182 DHerr(DH_F_DH_CHECK_PUB_KEY_EX
, DH_R_CHECK_PUBKEY_TOO_SMALL
);
183 if ((errflags
& DH_CHECK_PUBKEY_TOO_LARGE
) != 0)
184 DHerr(DH_F_DH_CHECK_PUB_KEY_EX
, DH_R_CHECK_PUBKEY_TOO_LARGE
);
185 if ((errflags
& DH_CHECK_PUBKEY_INVALID
) != 0)
186 DHerr(DH_F_DH_CHECK_PUB_KEY_EX
, DH_R_CHECK_PUBKEY_INVALID
);
188 return errflags
== 0;
191 int DH_check_pub_key(const DH
*dh
, const BIGNUM
*pub_key
, int *ret
)
202 tmp
= BN_CTX_get(ctx
);
203 if (tmp
== NULL
|| !BN_set_word(tmp
, 1))
205 if (BN_cmp(pub_key
, tmp
) <= 0)
206 *ret
|= DH_CHECK_PUBKEY_TOO_SMALL
;
207 if (BN_copy(tmp
, dh
->p
) == NULL
|| !BN_sub_word(tmp
, 1))
209 if (BN_cmp(pub_key
, tmp
) >= 0)
210 *ret
|= DH_CHECK_PUBKEY_TOO_LARGE
;
213 /* Check pub_key^q == 1 mod p */
214 if (!BN_mod_exp(tmp
, pub_key
, dh
->q
, dh
->p
, ctx
))
217 *ret
|= DH_CHECK_PUBKEY_INVALID
;