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