srp_lib.c revision 306195 
1/* crypto/srp/srp_lib.c */
2/*
3 * Written by Christophe Renou (christophe.renou@edelweb.fr) with the
4 * precious help of Peter Sylvester (peter.sylvester@edelweb.fr) for the
5 * EdelKey project and contributed to the OpenSSL project 2004.
6 */
7/* ====================================================================
8 * Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 *
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 *
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in
19 *    the documentation and/or other materials provided with the
20 *    distribution.
21 *
22 * 3. All advertising materials mentioning features or use of this
23 *    software must display the following acknowledgment:
24 *    "This product includes software developed by the OpenSSL Project
25 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
26 *
27 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
28 *    endorse or promote products derived from this software without
29 *    prior written permission. For written permission, please contact
30 *    licensing@OpenSSL.org.
31 *
32 * 5. Products derived from this software may not be called "OpenSSL"
33 *    nor may "OpenSSL" appear in their names without prior written
34 *    permission of the OpenSSL Project.
35 *
36 * 6. Redistributions of any form whatsoever must retain the following
37 *    acknowledgment:
38 *    "This product includes software developed by the OpenSSL Project
39 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
42 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
44 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
47 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
48 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
49 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
50 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
51 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
52 * OF THE POSSIBILITY OF SUCH DAMAGE.
53 * ====================================================================
54 *
55 * This product includes cryptographic software written by Eric Young
56 * (eay@cryptsoft.com).  This product includes software written by Tim
57 * Hudson (tjh@cryptsoft.com).
58 *
59 */
60#ifndef OPENSSL_NO_SRP
61# include "cryptlib.h"
62# include "srp_lcl.h"
63# include <openssl/srp.h>
64# include <openssl/evp.h>
65
66# if (BN_BYTES == 8)
67#  if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__)
68#   define bn_pack4(a1,a2,a3,a4) ((a1##UI64<<48)|(a2##UI64<<32)|(a3##UI64<<16)|a4##UI64)
69#  elif defined(__arch64__)
70#   define bn_pack4(a1,a2,a3,a4) ((a1##UL<<48)|(a2##UL<<32)|(a3##UL<<16)|a4##UL)
71#  else
72#   define bn_pack4(a1,a2,a3,a4) ((a1##ULL<<48)|(a2##ULL<<32)|(a3##ULL<<16)|a4##ULL)
73#  endif
74# elif (BN_BYTES == 4)
75#  define bn_pack4(a1,a2,a3,a4)  ((a3##UL<<16)|a4##UL), ((a1##UL<<16)|a2##UL)
76# else
77#  error "unsupported BN_BYTES"
78# endif
79
80# include "srp_grps.h"
81
82static BIGNUM *srp_Calc_k(BIGNUM *N, BIGNUM *g)
83{
84    /* k = SHA1(N | PAD(g)) -- tls-srp draft 8 */
85
86    unsigned char digest[SHA_DIGEST_LENGTH];
87    unsigned char *tmp;
88    EVP_MD_CTX ctxt;
89    int longg;
90    int longN = BN_num_bytes(N);
91
92    if (BN_ucmp(g, N) >= 0)
93        return NULL;
94
95    if ((tmp = OPENSSL_malloc(longN)) == NULL)
96        return NULL;
97    BN_bn2bin(N, tmp);
98
99    EVP_MD_CTX_init(&ctxt);
100    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
101    EVP_DigestUpdate(&ctxt, tmp, longN);
102
103    memset(tmp, 0, longN);
104    longg = BN_bn2bin(g, tmp);
105    /* use the zeros behind to pad on left */
106    EVP_DigestUpdate(&ctxt, tmp + longg, longN - longg);
107    EVP_DigestUpdate(&ctxt, tmp, longg);
108    OPENSSL_free(tmp);
109
110    EVP_DigestFinal_ex(&ctxt, digest, NULL);
111    EVP_MD_CTX_cleanup(&ctxt);
112    return BN_bin2bn(digest, sizeof(digest), NULL);
113}
114
115BIGNUM *SRP_Calc_u(BIGNUM *A, BIGNUM *B, BIGNUM *N)
116{
117    /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
118
119    BIGNUM *u;
120    unsigned char cu[SHA_DIGEST_LENGTH];
121    unsigned char *cAB;
122    EVP_MD_CTX ctxt;
123    int longN;
124    if ((A == NULL) || (B == NULL) || (N == NULL))
125        return NULL;
126
127    if (BN_ucmp(A, N) >= 0 || BN_ucmp(B, N) >= 0)
128        return NULL;
129
130    longN = BN_num_bytes(N);
131
132    if ((cAB = OPENSSL_malloc(2 * longN)) == NULL)
133        return NULL;
134
135    memset(cAB, 0, longN);
136
137    EVP_MD_CTX_init(&ctxt);
138    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
139    EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(A, cAB + longN), longN);
140    EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(B, cAB + longN), longN);
141    OPENSSL_free(cAB);
142    EVP_DigestFinal_ex(&ctxt, cu, NULL);
143    EVP_MD_CTX_cleanup(&ctxt);
144
145    if (!(u = BN_bin2bn(cu, sizeof(cu), NULL)))
146        return NULL;
147    if (!BN_is_zero(u))
148        return u;
149    BN_free(u);
150    return NULL;
151}
152
153BIGNUM *SRP_Calc_server_key(BIGNUM *A, BIGNUM *v, BIGNUM *u, BIGNUM *b,
154                            BIGNUM *N)
155{
156    BIGNUM *tmp = NULL, *S = NULL;
157    BN_CTX *bn_ctx;
158
159    if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
160        return NULL;
161
162    if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)
163        goto err;
164
165    /* S = (A*v**u) ** b */
166
167    if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
168        goto err;
169    if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))
170        goto err;
171
172    S = BN_new();
173    if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {
174        BN_free(S);
175        S = NULL;
176    }
177 err:
178    BN_CTX_free(bn_ctx);
179    BN_clear_free(tmp);
180    return S;
181}
182
183BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, BIGNUM *v)
184{
185    BIGNUM *kv = NULL, *gb = NULL;
186    BIGNUM *B = NULL, *k = NULL;
187    BN_CTX *bn_ctx;
188
189    if (b == NULL || N == NULL || g == NULL || v == NULL ||
190        (bn_ctx = BN_CTX_new()) == NULL)
191        return NULL;
192
193    if ((kv = BN_new()) == NULL ||
194        (gb = BN_new()) == NULL || (B = BN_new()) == NULL)
195        goto err;
196
197    /* B = g**b + k*v */
198
199    if (!BN_mod_exp(gb, g, b, N, bn_ctx) ||
200        !(k = srp_Calc_k(N, g)) ||
201        !BN_mod_mul(kv, v, k, N, bn_ctx) ||
202        !BN_mod_add(B, gb, kv, N, bn_ctx)) {
203        BN_free(B);
204        B = NULL;
205    }
206 err:
207    BN_CTX_free(bn_ctx);
208    BN_clear_free(kv);
209    BN_clear_free(gb);
210    BN_free(k);
211    return B;
212}
213
214BIGNUM *SRP_Calc_x(BIGNUM *s, const char *user, const char *pass)
215{
216    unsigned char dig[SHA_DIGEST_LENGTH];
217    EVP_MD_CTX ctxt;
218    unsigned char *cs;
219
220    if ((s == NULL) || (user == NULL) || (pass == NULL))
221        return NULL;
222
223    if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
224        return NULL;
225
226    EVP_MD_CTX_init(&ctxt);
227    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
228    EVP_DigestUpdate(&ctxt, user, strlen(user));
229    EVP_DigestUpdate(&ctxt, ":", 1);
230    EVP_DigestUpdate(&ctxt, pass, strlen(pass));
231    EVP_DigestFinal_ex(&ctxt, dig, NULL);
232
233    EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
234    BN_bn2bin(s, cs);
235    EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s));
236    OPENSSL_free(cs);
237    EVP_DigestUpdate(&ctxt, dig, sizeof(dig));
238    EVP_DigestFinal_ex(&ctxt, dig, NULL);
239    EVP_MD_CTX_cleanup(&ctxt);
240
241    return BN_bin2bn(dig, sizeof(dig), NULL);
242}
243
244BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, BIGNUM *g)
245{
246    BN_CTX *bn_ctx;
247    BIGNUM *A = NULL;
248
249    if (a == NULL || N == NULL || g == NULL ||
250        (bn_ctx = BN_CTX_new()) == NULL)
251        return NULL;
252
253    if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
254        BN_free(A);
255        A = NULL;
256    }
257    BN_CTX_free(bn_ctx);
258    return A;
259}
260
261BIGNUM *SRP_Calc_client_key(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x,
262                            BIGNUM *a, BIGNUM *u)
263{
264    BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
265    BN_CTX *bn_ctx;
266
267    if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
268        || a == NULL || (bn_ctx = BN_CTX_new()) == NULL)
269        return NULL;
270
271    if ((tmp = BN_new()) == NULL ||
272        (tmp2 = BN_new()) == NULL ||
273        (tmp3 = BN_new()) == NULL)
274        goto err;
275
276    if (!BN_mod_exp(tmp, g, x, N, bn_ctx))
277        goto err;
278    if (!(k = srp_Calc_k(N, g)))
279        goto err;
280    if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
281        goto err;
282    if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
283        goto err;
284
285    if (!BN_mul(tmp3, u, x, bn_ctx))
286        goto err;
287    if (!BN_add(tmp2, a, tmp3))
288        goto err;
289    K = BN_new();
290    if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
291        BN_free(K);
292        K = NULL;
293    }
294
295 err:
296    BN_CTX_free(bn_ctx);
297    BN_clear_free(tmp);
298    BN_clear_free(tmp2);
299    BN_clear_free(tmp3);
300    BN_free(k);
301    return K;
302}
303
304int SRP_Verify_B_mod_N(BIGNUM *B, BIGNUM *N)
305{
306    BIGNUM *r;
307    BN_CTX *bn_ctx;
308    int ret = 0;
309
310    if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
311        return 0;
312
313    if ((r = BN_new()) == NULL)
314        goto err;
315    /* Checks if B % N == 0 */
316    if (!BN_nnmod(r, B, N, bn_ctx))
317        goto err;
318    ret = !BN_is_zero(r);
319 err:
320    BN_CTX_free(bn_ctx);
321    BN_free(r);
322    return ret;
323}
324
325int SRP_Verify_A_mod_N(BIGNUM *A, BIGNUM *N)
326{
327    /* Checks if A % N == 0 */
328    return SRP_Verify_B_mod_N(A, N);
329}
330
331/*
332 * Check if G and N are kwown parameters. The values have been generated
333 * from the ietf-tls-srp draft version 8
334 */
335char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N)
336{
337    size_t i;
338    if ((g == NULL) || (N == NULL))
339        return 0;
340
341    srp_bn_print(g);
342    srp_bn_print(N);
343
344    for (i = 0; i < KNOWN_GN_NUMBER; i++) {
345        if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
346            return knowngN[i].id;
347    }
348    return NULL;
349}
350
351SRP_gN *SRP_get_default_gN(const char *id)
352{
353    size_t i;
354
355    if (id == NULL)
356        return knowngN;
357    for (i = 0; i < KNOWN_GN_NUMBER; i++) {
358        if (strcmp(knowngN[i].id, id) == 0)
359            return knowngN + i;
360    }
361    return NULL;
362}
363#endif
364