1 /*
2 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
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
8 */
9
10 /*
11 * DH low level APIs are deprecated for public use, but still ok for
12 * internal use.
13 */
14 #include "internal/deprecated.h"
15
16 #include <stdio.h>
17 #include "internal/cryptlib.h"
18 #include <openssl/bn.h>
19 #include "dh_local.h"
20 #include "crypto/dh.h"
21
22 /*-
23 * Check that p and g are suitable enough
24 *
25 * p is odd
26 * 1 < g < p - 1
27 */
DH_check_params_ex(const DH * dh)28 int DH_check_params_ex(const DH *dh)
29 {
30 int errflags = 0;
31
32 if (!DH_check_params(dh, &errflags))
33 return 0;
34
35 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
36 ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
37 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
38 ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
39 if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
40 ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
41 if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
42 ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
43
44 return errflags == 0;
45 }
46
47 #ifdef FIPS_MODULE
DH_check_params(const DH * dh,int * ret)48 int DH_check_params(const DH *dh, int *ret)
49 {
50 int nid;
51
52 *ret = 0;
53 /*
54 * SP800-56A R3 Section 5.5.2 Assurances of Domain Parameter Validity
55 * (1a) The domain parameters correspond to any approved safe prime group.
56 */
57 nid = DH_get_nid((DH *)dh);
58 if (nid != NID_undef)
59 return 1;
60 /*
61 * OR
62 * (2b) FFC domain params conform to FIPS-186-4 explicit domain param
63 * validity tests.
64 */
65 return ossl_ffc_params_FIPS186_4_validate(dh->libctx, &dh->params,
66 FFC_PARAM_TYPE_DH, ret, NULL);
67 }
68 #else
DH_check_params(const DH * dh,int * ret)69 int DH_check_params(const DH *dh, int *ret)
70 {
71 int ok = 0;
72 BIGNUM *tmp = NULL;
73 BN_CTX *ctx = NULL;
74
75 *ret = 0;
76 ctx = BN_CTX_new();
77 if (ctx == NULL)
78 goto err;
79 BN_CTX_start(ctx);
80 tmp = BN_CTX_get(ctx);
81 if (tmp == NULL)
82 goto err;
83
84 if (!BN_is_odd(dh->params.p))
85 *ret |= DH_CHECK_P_NOT_PRIME;
86 if (BN_is_negative(dh->params.g)
87 || BN_is_zero(dh->params.g)
88 || BN_is_one(dh->params.g))
89 *ret |= DH_NOT_SUITABLE_GENERATOR;
90 if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1))
91 goto err;
92 if (BN_cmp(dh->params.g, tmp) >= 0)
93 *ret |= DH_NOT_SUITABLE_GENERATOR;
94 if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS)
95 *ret |= DH_MODULUS_TOO_SMALL;
96 if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS)
97 *ret |= DH_MODULUS_TOO_LARGE;
98
99 ok = 1;
100 err:
101 BN_CTX_end(ctx);
102 BN_CTX_free(ctx);
103 return ok;
104 }
105 #endif /* FIPS_MODULE */
106
107 /*-
108 * Check that p is a safe prime and
109 * g is a suitable generator.
110 */
DH_check_ex(const DH * dh)111 int DH_check_ex(const DH *dh)
112 {
113 int errflags = 0;
114
115 if (!DH_check(dh, &errflags))
116 return 0;
117
118 if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
119 ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
120 if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
121 ERR_raise(ERR_LIB_DH, DH_R_CHECK_Q_NOT_PRIME);
122 if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
123 ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_Q_VALUE);
124 if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
125 ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_J_VALUE);
126 if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
127 ERR_raise(ERR_LIB_DH, DH_R_UNABLE_TO_CHECK_GENERATOR);
128 if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
129 ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
130 if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
131 ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_SAFE_PRIME);
132 if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
133 ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
134 if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
135 ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
136
137 return errflags == 0;
138 }
139
140 /* Note: according to documentation - this only checks the params */
DH_check(const DH * dh,int * ret)141 int DH_check(const DH *dh, int *ret)
142 {
143 #ifdef FIPS_MODULE
144 return DH_check_params(dh, ret);
145 #else
146 int ok = 0, r;
147 BN_CTX *ctx = NULL;
148 BIGNUM *t1 = NULL, *t2 = NULL;
149 int nid = DH_get_nid((DH *)dh);
150
151 *ret = 0;
152 if (nid != NID_undef)
153 return 1;
154
155 if (!DH_check_params(dh, ret))
156 return 0;
157
158 ctx = BN_CTX_new();
159 if (ctx == NULL)
160 goto err;
161 BN_CTX_start(ctx);
162 t1 = BN_CTX_get(ctx);
163 t2 = BN_CTX_get(ctx);
164 if (t2 == NULL)
165 goto err;
166
167 if (dh->params.q != NULL) {
168 if (BN_cmp(dh->params.g, BN_value_one()) <= 0)
169 *ret |= DH_NOT_SUITABLE_GENERATOR;
170 else if (BN_cmp(dh->params.g, dh->params.p) >= 0)
171 *ret |= DH_NOT_SUITABLE_GENERATOR;
172 else {
173 /* Check g^q == 1 mod p */
174 if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx))
175 goto err;
176 if (!BN_is_one(t1))
177 *ret |= DH_NOT_SUITABLE_GENERATOR;
178 }
179 r = BN_check_prime(dh->params.q, ctx, NULL);
180 if (r < 0)
181 goto err;
182 if (!r)
183 *ret |= DH_CHECK_Q_NOT_PRIME;
184 /* Check p == 1 mod q i.e. q divides p - 1 */
185 if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx))
186 goto err;
187 if (!BN_is_one(t2))
188 *ret |= DH_CHECK_INVALID_Q_VALUE;
189 if (dh->params.j != NULL
190 && BN_cmp(dh->params.j, t1))
191 *ret |= DH_CHECK_INVALID_J_VALUE;
192 }
193
194 r = BN_check_prime(dh->params.p, ctx, NULL);
195 if (r < 0)
196 goto err;
197 if (!r)
198 *ret |= DH_CHECK_P_NOT_PRIME;
199 else if (dh->params.q == NULL) {
200 if (!BN_rshift1(t1, dh->params.p))
201 goto err;
202 r = BN_check_prime(t1, ctx, NULL);
203 if (r < 0)
204 goto err;
205 if (!r)
206 *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
207 }
208 ok = 1;
209 err:
210 BN_CTX_end(ctx);
211 BN_CTX_free(ctx);
212 return ok;
213 #endif /* FIPS_MODULE */
214 }
215
DH_check_pub_key_ex(const DH * dh,const BIGNUM * pub_key)216 int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
217 {
218 int errflags = 0;
219
220 if (!DH_check_pub_key(dh, pub_key, &errflags))
221 return 0;
222
223 if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
224 ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_SMALL);
225 if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
226 ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_LARGE);
227 if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
228 ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_INVALID);
229
230 return errflags == 0;
231 }
232
233 /*
234 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
235 */
DH_check_pub_key(const DH * dh,const BIGNUM * pub_key,int * ret)236 int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
237 {
238 return ossl_ffc_validate_public_key(&dh->params, pub_key, ret);
239 }
240
241 /*
242 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
243 * To only be used with ephemeral FFC public keys generated using the approved
244 * safe-prime groups.
245 */
ossl_dh_check_pub_key_partial(const DH * dh,const BIGNUM * pub_key,int * ret)246 int ossl_dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret)
247 {
248 return ossl_ffc_validate_public_key_partial(&dh->params, pub_key, ret);
249 }
250
ossl_dh_check_priv_key(const DH * dh,const BIGNUM * priv_key,int * ret)251 int ossl_dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret)
252 {
253 int ok = 0;
254 BIGNUM *two_powN = NULL, *upper;
255
256 *ret = 0;
257 two_powN = BN_new();
258 if (two_powN == NULL)
259 return 0;
260
261 if (dh->params.q != NULL) {
262 upper = dh->params.q;
263 #ifndef FIPS_MODULE
264 } else if (dh->params.p != NULL) {
265 /*
266 * We do not have q so we just check the key is within some
267 * reasonable range, or the number of bits is equal to dh->length.
268 */
269 int length = dh->length;
270
271 if (length == 0) {
272 length = BN_num_bits(dh->params.p) - 1;
273 if (BN_num_bits(priv_key) <= length
274 && BN_num_bits(priv_key) > 1)
275 ok = 1;
276 } else if (BN_num_bits(priv_key) == length) {
277 ok = 1;
278 }
279 goto end;
280 #endif
281 } else {
282 goto end;
283 }
284
285 /* Is it from an approved Safe prime group ?*/
286 if (DH_get_nid((DH *)dh) != NID_undef && dh->length != 0) {
287 if (!BN_lshift(two_powN, BN_value_one(), dh->length))
288 goto end;
289 if (BN_cmp(two_powN, dh->params.q) < 0)
290 upper = two_powN;
291 }
292 if (!ossl_ffc_validate_private_key(upper, priv_key, ret))
293 goto end;
294
295 ok = 1;
296 end:
297 BN_free(two_powN);
298 return ok;
299 }
300
301 /*
302 * FFC pairwise check from SP800-56A R3.
303 * Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
304 */
ossl_dh_check_pairwise(const DH * dh)305 int ossl_dh_check_pairwise(const DH *dh)
306 {
307 int ret = 0;
308 BN_CTX *ctx = NULL;
309 BIGNUM *pub_key = NULL;
310
311 if (dh->params.p == NULL
312 || dh->params.g == NULL
313 || dh->priv_key == NULL
314 || dh->pub_key == NULL)
315 return 0;
316
317 ctx = BN_CTX_new_ex(dh->libctx);
318 if (ctx == NULL)
319 goto err;
320 pub_key = BN_new();
321 if (pub_key == NULL)
322 goto err;
323
324 /* recalculate the public key = (g ^ priv) mod p */
325 if (!ossl_dh_generate_public_key(ctx, dh, dh->priv_key, pub_key))
326 goto err;
327 /* check it matches the existing pubic_key */
328 ret = BN_cmp(pub_key, dh->pub_key) == 0;
329 err:
330 BN_free(pub_key);
331 BN_CTX_free(ctx);
332 return ret;
333 }
334
