Coverage Report

Created: 2024-11-21 07:03

/src/openssl/crypto/dh/dh_check.c
Line
Count
Source (jump to first uncovered line)
1
/*
2
 * Copyright 1995-2024 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
 */
28
int DH_check_params_ex(const DH *dh)
29
0
{
30
0
    int errflags = 0;
31
32
0
    if (!DH_check_params(dh, &errflags))
33
0
        return 0;
34
35
0
    if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
36
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
37
0
    if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
38
0
        ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
39
0
    if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
40
0
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
41
0
    if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
42
0
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
43
44
0
    return errflags == 0;
45
0
}
46
47
#ifdef FIPS_MODULE
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
69
int DH_check_params(const DH *dh, int *ret)
70
0
{
71
0
    int ok = 0;
72
0
    BIGNUM *tmp = NULL;
73
0
    BN_CTX *ctx = NULL;
74
75
0
    *ret = 0;
76
0
    ctx = BN_CTX_new_ex(dh->libctx);
77
0
    if (ctx == NULL)
78
0
        goto err;
79
0
    BN_CTX_start(ctx);
80
0
    tmp = BN_CTX_get(ctx);
81
0
    if (tmp == NULL)
82
0
        goto err;
83
84
0
    if (!BN_is_odd(dh->params.p))
85
0
        *ret |= DH_CHECK_P_NOT_PRIME;
86
0
    if (BN_is_negative(dh->params.g)
87
0
        || BN_is_zero(dh->params.g)
88
0
        || BN_is_one(dh->params.g))
89
0
        *ret |= DH_NOT_SUITABLE_GENERATOR;
90
0
    if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1))
91
0
        goto err;
92
0
    if (BN_cmp(dh->params.g, tmp) >= 0)
93
0
        *ret |= DH_NOT_SUITABLE_GENERATOR;
94
0
    if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS)
95
0
        *ret |= DH_MODULUS_TOO_SMALL;
96
0
    if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS)
97
0
        *ret |= DH_MODULUS_TOO_LARGE;
98
99
0
    ok = 1;
100
0
 err:
101
0
    BN_CTX_end(ctx);
102
0
    BN_CTX_free(ctx);
103
0
    return ok;
104
0
}
105
#endif /* FIPS_MODULE */
106
107
/*-
108
 * Check that p is a safe prime and
109
 * g is a suitable generator.
110
 */
111
int DH_check_ex(const DH *dh)
112
0
{
113
0
    int errflags = 0;
114
115
0
    if (!DH_check(dh, &errflags))
116
0
        return 0;
117
118
0
    if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
119
0
        ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
120
0
    if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
121
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_Q_NOT_PRIME);
122
0
    if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
123
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_Q_VALUE);
124
0
    if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
125
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_J_VALUE);
126
0
    if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
127
0
        ERR_raise(ERR_LIB_DH, DH_R_UNABLE_TO_CHECK_GENERATOR);
128
0
    if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
129
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
130
0
    if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
131
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_SAFE_PRIME);
132
0
    if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
133
0
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
134
0
    if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
135
0
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
136
137
0
    return errflags == 0;
138
0
}
139
140
/* Note: according to documentation - this only checks the params */
141
int DH_check(const DH *dh, int *ret)
142
0
{
143
#ifdef FIPS_MODULE
144
    return DH_check_params(dh, ret);
145
#else
146
0
    int ok = 0, r, q_good = 0;
147
0
    BN_CTX *ctx = NULL;
148
0
    BIGNUM *t1 = NULL, *t2 = NULL;
149
0
    int nid = DH_get_nid((DH *)dh);
150
151
0
    *ret = 0;
152
0
    if (nid != NID_undef)
153
0
        return 1;
154
155
    /* Don't do any checks at all with an excessively large modulus */
156
0
    if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
157
0
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
158
0
        *ret = DH_MODULUS_TOO_LARGE | DH_CHECK_P_NOT_PRIME;
159
0
        return 0;
160
0
    }
161
162
0
    if (!DH_check_params(dh, ret))
163
0
        return 0;
164
165
0
    ctx = BN_CTX_new_ex(dh->libctx);
166
0
    if (ctx == NULL)
167
0
        goto err;
168
0
    BN_CTX_start(ctx);
169
0
    t1 = BN_CTX_get(ctx);
170
0
    t2 = BN_CTX_get(ctx);
171
0
    if (t2 == NULL)
172
0
        goto err;
173
174
0
    if (dh->params.q != NULL) {
175
0
        if (BN_ucmp(dh->params.p, dh->params.q) > 0)
176
0
            q_good = 1;
177
0
        else
178
0
            *ret |= DH_CHECK_INVALID_Q_VALUE;
179
0
    }
180
181
0
    if (q_good) {
182
0
        if (BN_cmp(dh->params.g, BN_value_one()) <= 0)
183
0
            *ret |= DH_NOT_SUITABLE_GENERATOR;
184
0
        else if (BN_cmp(dh->params.g, dh->params.p) >= 0)
185
0
            *ret |= DH_NOT_SUITABLE_GENERATOR;
186
0
        else {
187
            /* Check g^q == 1 mod p */
188
0
            if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx))
189
0
                goto err;
190
0
            if (!BN_is_one(t1))
191
0
                *ret |= DH_NOT_SUITABLE_GENERATOR;
192
0
        }
193
0
        r = BN_check_prime(dh->params.q, ctx, NULL);
194
0
        if (r < 0)
195
0
            goto err;
196
0
        if (!r)
197
0
            *ret |= DH_CHECK_Q_NOT_PRIME;
198
        /* Check p == 1 mod q  i.e. q divides p - 1 */
199
0
        if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx))
200
0
            goto err;
201
0
        if (!BN_is_one(t2))
202
0
            *ret |= DH_CHECK_INVALID_Q_VALUE;
203
0
        if (dh->params.j != NULL
204
0
            && BN_cmp(dh->params.j, t1))
205
0
            *ret |= DH_CHECK_INVALID_J_VALUE;
206
0
    }
207
208
0
    r = BN_check_prime(dh->params.p, ctx, NULL);
209
0
    if (r < 0)
210
0
        goto err;
211
0
    if (!r)
212
0
        *ret |= DH_CHECK_P_NOT_PRIME;
213
0
    else if (dh->params.q == NULL) {
214
0
        if (!BN_rshift1(t1, dh->params.p))
215
0
            goto err;
216
0
        r = BN_check_prime(t1, ctx, NULL);
217
0
        if (r < 0)
218
0
            goto err;
219
0
        if (!r)
220
0
            *ret |= DH_CHECK_P_NOT_SAFE_PRIME;
221
0
    }
222
0
    ok = 1;
223
0
 err:
224
0
    BN_CTX_end(ctx);
225
0
    BN_CTX_free(ctx);
226
0
    return ok;
227
0
#endif /* FIPS_MODULE */
228
0
}
229
230
int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
231
0
{
232
0
    int errflags = 0;
233
234
0
    if (!DH_check_pub_key(dh, pub_key, &errflags))
235
0
        return 0;
236
237
0
    if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
238
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_SMALL);
239
0
    if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
240
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_LARGE);
241
0
    if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
242
0
        ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_INVALID);
243
244
0
    return errflags == 0;
245
0
}
246
247
/*
248
 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
249
 */
250
int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
251
{
252
    /* Don't do any checks at all with an excessively large modulus */
253
    if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
254
        ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
255
        *ret = DH_MODULUS_TOO_LARGE | DH_CHECK_PUBKEY_INVALID;
256
        return 0;
257
    }
258
259
    if (dh->params.q != NULL && BN_ucmp(dh->params.p, dh->params.q) < 0) {
260
        *ret |= DH_CHECK_INVALID_Q_VALUE | DH_CHECK_PUBKEY_INVALID;
261
        return 1;
262
    }
263
264
    return ossl_ffc_validate_public_key(&dh->params, pub_key, ret);
265
}
266
267
/*
268
 * See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
269
 * To only be used with ephemeral FFC public keys generated using the approved
270
 * safe-prime groups.
271
 */
272
int ossl_dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret)
273
0
{
274
0
    return ossl_ffc_validate_public_key_partial(&dh->params, pub_key, ret)
275
0
           && *ret == 0;
276
0
}
277
278
int ossl_dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret)
279
0
{
280
0
    int ok = 0;
281
0
    BIGNUM *two_powN = NULL, *upper;
282
283
0
    *ret = 0;
284
0
    two_powN = BN_new();
285
0
    if (two_powN == NULL)
286
0
        return 0;
287
288
0
    if (dh->params.q != NULL) {
289
0
        upper = dh->params.q;
290
0
#ifndef FIPS_MODULE
291
0
    } else if (dh->params.p != NULL) {
292
        /*
293
         * We do not have q so we just check the key is within some
294
         * reasonable range, or the number of bits is equal to dh->length.
295
         */
296
0
        int length = dh->length;
297
298
0
        if (length == 0) {
299
0
            length = BN_num_bits(dh->params.p) - 1;
300
0
            if (BN_num_bits(priv_key) <= length
301
0
                && BN_num_bits(priv_key) > 1)
302
0
                ok = 1;
303
0
        } else if (BN_num_bits(priv_key) == length) {
304
0
            ok = 1;
305
0
        }
306
0
        goto end;
307
0
#endif
308
0
    } else {
309
0
        goto end;
310
0
    }
311
312
    /* Is it from an approved Safe prime group ?*/
313
0
    if (DH_get_nid((DH *)dh) != NID_undef && dh->length != 0) {
314
0
        if (!BN_lshift(two_powN, BN_value_one(), dh->length))
315
0
            goto end;
316
0
        if (BN_cmp(two_powN, dh->params.q) < 0)
317
0
            upper = two_powN;
318
0
    }
319
0
    if (!ossl_ffc_validate_private_key(upper, priv_key, ret))
320
0
        goto end;
321
322
0
    ok = 1;
323
0
end:
324
0
    BN_free(two_powN);
325
0
    return ok;
326
0
}
327
328
/*
329
 * FFC pairwise check from SP800-56A R3.
330
 *    Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
331
 */
332
int ossl_dh_check_pairwise(const DH *dh)
333
0
{
334
0
    int ret = 0;
335
0
    BN_CTX *ctx = NULL;
336
0
    BIGNUM *pub_key = NULL;
337
338
0
    if (dh->params.p == NULL
339
0
        || dh->params.g == NULL
340
0
        || dh->priv_key == NULL
341
0
        || dh->pub_key == NULL)
342
0
        return 0;
343
344
0
    ctx = BN_CTX_new_ex(dh->libctx);
345
0
    if (ctx == NULL)
346
0
        goto err;
347
0
    pub_key = BN_new();
348
0
    if (pub_key == NULL)
349
0
        goto err;
350
351
    /* recalculate the public key = (g ^ priv) mod p */
352
0
    if (!ossl_dh_generate_public_key(ctx, dh, dh->priv_key, pub_key))
353
0
        goto err;
354
    /* check it matches the existing public_key */
355
0
    ret = BN_cmp(pub_key, dh->pub_key) == 0;
356
0
err:
357
0
    BN_free(pub_key);
358
0
    BN_CTX_free(ctx);
359
0
    return ret;
360
0
}