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 # if (defined(_WIN32) || defined(_WIN64)) && !defined(__MINGW32__)
67 # define bn_pack4(a1,a2,a3,a4) ((a1##UI64<<48)|(a2##UI64<<32)|(a3##UI64<<16)|a4##UI64)
68 # elif defined(__arch64__)
69 # define bn_pack4(a1,a2,a3,a4) ((a1##UL<<48)|(a2##UL<<32)|(a3##UL<<16)|a4##UL)
70 # else
71 # define bn_pack4(a1,a2,a3,a4) ((a1##ULL<<48)|(a2##ULL<<32)|(a3##ULL<<16)|a4##ULL)
72 # endif
73 #elif (BN_BYTES == 4)
74 # define bn_pack4(a1,a2,a3,a4) ((a3##UL<<16)|a4##UL), ((a1##UL<<16)|a2##UL)
75 #else
76 # error "unsupported BN_BYTES"
77 #endif
78
79
80 #include "srp_grps.h"
81
srp_Calc_k(BIGNUM * N,BIGNUM * g)82 static 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 ((tmp = OPENSSL_malloc(longN)) == NULL)
93 return NULL;
94 BN_bn2bin(N,tmp) ;
95
96 EVP_MD_CTX_init(&ctxt);
97 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
98 EVP_DigestUpdate(&ctxt, tmp, longN);
99
100 memset(tmp, 0, longN);
101 longg = BN_bn2bin(g,tmp) ;
102 /* use the zeros behind to pad on left */
103 EVP_DigestUpdate(&ctxt, tmp + longg, longN-longg);
104 EVP_DigestUpdate(&ctxt, tmp, longg);
105 OPENSSL_free(tmp);
106
107 EVP_DigestFinal_ex(&ctxt, digest, NULL);
108 EVP_MD_CTX_cleanup(&ctxt);
109 return BN_bin2bn(digest, sizeof(digest), NULL);
110 }
111
SRP_Calc_u(BIGNUM * A,BIGNUM * B,BIGNUM * N)112 BIGNUM *SRP_Calc_u(BIGNUM *A, BIGNUM *B, BIGNUM *N)
113 {
114 /* k = SHA1(PAD(A) || PAD(B) ) -- tls-srp draft 8 */
115
116 BIGNUM *u;
117 unsigned char cu[SHA_DIGEST_LENGTH];
118 unsigned char *cAB;
119 EVP_MD_CTX ctxt;
120 int longN;
121 if ((A == NULL) ||(B == NULL) || (N == NULL))
122 return NULL;
123
124 longN= BN_num_bytes(N);
125
126 if ((cAB = OPENSSL_malloc(2*longN)) == NULL)
127 return NULL;
128
129 memset(cAB, 0, longN);
130
131 EVP_MD_CTX_init(&ctxt);
132 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
133 EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(A,cAB+longN), longN);
134 EVP_DigestUpdate(&ctxt, cAB + BN_bn2bin(B,cAB+longN), longN);
135 OPENSSL_free(cAB);
136 EVP_DigestFinal_ex(&ctxt, cu, NULL);
137 EVP_MD_CTX_cleanup(&ctxt);
138
139 if (!(u = BN_bin2bn(cu, sizeof(cu), NULL)))
140 return NULL;
141 if (!BN_is_zero(u))
142 return u;
143 BN_free(u);
144 return NULL;
145 }
146
SRP_Calc_server_key(BIGNUM * A,BIGNUM * v,BIGNUM * u,BIGNUM * b,BIGNUM * N)147 BIGNUM *SRP_Calc_server_key(BIGNUM *A, BIGNUM *v, BIGNUM *u, BIGNUM *b, BIGNUM *N)
148 {
149 BIGNUM *tmp = NULL, *S = NULL;
150 BN_CTX *bn_ctx;
151
152 if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
153 return NULL;
154
155 if ((bn_ctx = BN_CTX_new()) == NULL ||
156 (tmp = BN_new()) == NULL ||
157 (S = BN_new()) == NULL )
158 goto err;
159
160 /* S = (A*v**u) ** b */
161
162 if (!BN_mod_exp(tmp,v,u,N,bn_ctx))
163 goto err;
164 if (!BN_mod_mul(tmp,A,tmp,N,bn_ctx))
165 goto err;
166 if (!BN_mod_exp(S,tmp,b,N,bn_ctx))
167 goto err;
168 err:
169 BN_CTX_free(bn_ctx);
170 BN_clear_free(tmp);
171 return S;
172 }
173
SRP_Calc_B(BIGNUM * b,BIGNUM * N,BIGNUM * g,BIGNUM * v)174 BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, BIGNUM *v)
175 {
176 BIGNUM *kv = NULL, *gb = NULL;
177 BIGNUM *B = NULL, *k = NULL;
178 BN_CTX *bn_ctx;
179
180 if (b == NULL || N == NULL || g == NULL || v == NULL ||
181 (bn_ctx = BN_CTX_new()) == NULL)
182 return NULL;
183
184 if ( (kv = BN_new()) == NULL ||
185 (gb = BN_new()) == NULL ||
186 (B = BN_new())== NULL)
187 goto err;
188
189 /* B = g**b + k*v */
190
191 if (!BN_mod_exp(gb,g,b,N,bn_ctx) ||
192 !(k = srp_Calc_k(N,g)) ||
193 !BN_mod_mul(kv,v,k,N,bn_ctx) ||
194 !BN_mod_add(B,gb,kv,N,bn_ctx))
195 {
196 BN_free(B);
197 B = NULL;
198 }
199 err:
200 BN_CTX_free(bn_ctx);
201 BN_clear_free(kv);
202 BN_clear_free(gb);
203 BN_free(k);
204 return B;
205 }
206
SRP_Calc_x(BIGNUM * s,const char * user,const char * pass)207 BIGNUM *SRP_Calc_x(BIGNUM *s, const char *user, const char *pass)
208 {
209 unsigned char dig[SHA_DIGEST_LENGTH];
210 EVP_MD_CTX ctxt;
211 unsigned char *cs;
212
213 if ((s == NULL) ||
214 (user == NULL) ||
215 (pass == NULL))
216 return NULL;
217
218 if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
219 return NULL;
220
221 EVP_MD_CTX_init(&ctxt);
222 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
223 EVP_DigestUpdate(&ctxt, user, strlen(user));
224 EVP_DigestUpdate(&ctxt, ":", 1);
225 EVP_DigestUpdate(&ctxt, pass, strlen(pass));
226 EVP_DigestFinal_ex(&ctxt, dig, NULL);
227
228 EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
229 BN_bn2bin(s,cs);
230 EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s));
231 OPENSSL_free(cs);
232 EVP_DigestUpdate(&ctxt, dig, sizeof(dig));
233 EVP_DigestFinal_ex(&ctxt, dig, NULL);
234 EVP_MD_CTX_cleanup(&ctxt);
235
236 return BN_bin2bn(dig, sizeof(dig), NULL);
237 }
238
SRP_Calc_A(BIGNUM * a,BIGNUM * N,BIGNUM * g)239 BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, BIGNUM *g)
240 {
241 BN_CTX *bn_ctx;
242 BIGNUM * A = NULL;
243
244 if (a == NULL || N == NULL || g == NULL ||
245 (bn_ctx = BN_CTX_new()) == NULL)
246 return NULL;
247
248 if ((A = BN_new()) != NULL &&
249 !BN_mod_exp(A,g,a,N,bn_ctx))
250 {
251 BN_free(A);
252 A = NULL;
253 }
254 BN_CTX_free(bn_ctx);
255 return A;
256 }
257
258
SRP_Calc_client_key(BIGNUM * N,BIGNUM * B,BIGNUM * g,BIGNUM * x,BIGNUM * a,BIGNUM * u)259 BIGNUM *SRP_Calc_client_key(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x, BIGNUM *a, BIGNUM *u)
260 {
261 BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL , *k = NULL, *K = NULL;
262 BN_CTX *bn_ctx;
263
264 if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL || a == NULL ||
265 (bn_ctx = BN_CTX_new()) == NULL)
266 return NULL;
267
268 if ((tmp = BN_new()) == NULL ||
269 (tmp2 = BN_new())== NULL ||
270 (tmp3 = BN_new())== NULL ||
271 (K = BN_new()) == NULL)
272 goto err;
273
274 if (!BN_mod_exp(tmp,g,x,N,bn_ctx))
275 goto err;
276 if (!(k = srp_Calc_k(N,g)))
277 goto err;
278 if (!BN_mod_mul(tmp2,tmp,k,N,bn_ctx))
279 goto err;
280 if (!BN_mod_sub(tmp,B,tmp2,N,bn_ctx))
281 goto err;
282
283 if (!BN_mod_mul(tmp3,u,x,N,bn_ctx))
284 goto err;
285 if (!BN_mod_add(tmp2,a,tmp3,N,bn_ctx))
286 goto err;
287 if (!BN_mod_exp(K,tmp,tmp2,N,bn_ctx))
288 goto err;
289
290 err :
291 BN_CTX_free(bn_ctx);
292 BN_clear_free(tmp);
293 BN_clear_free(tmp2);
294 BN_clear_free(tmp3);
295 BN_free(k);
296 return K;
297 }
298
SRP_Verify_B_mod_N(BIGNUM * B,BIGNUM * N)299 int SRP_Verify_B_mod_N(BIGNUM *B, BIGNUM *N)
300 {
301 BIGNUM *r;
302 BN_CTX *bn_ctx;
303 int ret = 0;
304
305 if (B == NULL || N == NULL ||
306 (bn_ctx = BN_CTX_new()) == NULL)
307 return 0;
308
309 if ((r = BN_new()) == NULL)
310 goto err;
311 /* Checks if B % N == 0 */
312 if (!BN_nnmod(r,B,N,bn_ctx))
313 goto err;
314 ret = !BN_is_zero(r);
315 err:
316 BN_CTX_free(bn_ctx);
317 BN_free(r);
318 return ret;
319 }
320
SRP_Verify_A_mod_N(BIGNUM * A,BIGNUM * N)321 int SRP_Verify_A_mod_N(BIGNUM *A, BIGNUM *N)
322 {
323 /* Checks if A % N == 0 */
324 return SRP_Verify_B_mod_N(A,N) ;
325 }
326
327
328 /* Check if G and N are kwown parameters.
329 The values have been generated from the ietf-tls-srp draft version 8
330 */
SRP_check_known_gN_param(BIGNUM * g,BIGNUM * N)331 char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N)
332 {
333 size_t i;
334 if ((g == NULL) || (N == NULL))
335 return 0;
336
337 srp_bn_print(g);
338 srp_bn_print(N);
339
340 for(i = 0; i < KNOWN_GN_NUMBER; i++)
341 {
342 if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
343 return knowngN[i].id;
344 }
345 return NULL;
346 }
347
SRP_get_default_gN(const char * id)348 SRP_gN *SRP_get_default_gN(const char *id)
349 {
350 size_t i;
351
352 if (id == NULL)
353 return knowngN;
354 for(i = 0; i < KNOWN_GN_NUMBER; i++)
355 {
356 if (strcmp(knowngN[i].id, id)==0)
357 return knowngN + i;
358 }
359 return NULL;
360 }
361 #endif
362