srp_lib.c revision c64f6fe2be99cb3fa8e491b5bede9a217de87a4c 
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
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, BIGNUM *N)
154	{
155	BIGNUM *tmp = NULL, *S = NULL;
156	BN_CTX *bn_ctx;
157
158	if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
159		return NULL;
160
161	if ((bn_ctx = BN_CTX_new()) == NULL ||
162		(tmp = BN_new()) == NULL ||
163		(S = BN_new()) == NULL )
164		goto err;
165
166	/* S = (A*v**u) ** b */
167
168	if (!BN_mod_exp(tmp,v,u,N,bn_ctx))
169		goto err;
170	if (!BN_mod_mul(tmp,A,tmp,N,bn_ctx))
171		goto err;
172	if (!BN_mod_exp(S,tmp,b,N,bn_ctx))
173		goto err;
174err:
175	BN_CTX_free(bn_ctx);
176	BN_clear_free(tmp);
177	return S;
178	}
179
180BIGNUM *SRP_Calc_B(BIGNUM *b, BIGNUM *N, BIGNUM *g, BIGNUM *v)
181	{
182	BIGNUM  *kv = NULL, *gb = NULL;
183	BIGNUM *B = NULL, *k = NULL;
184	BN_CTX *bn_ctx;
185
186	if (b == NULL || N == NULL || g == NULL || v == NULL ||
187		(bn_ctx = BN_CTX_new()) == NULL)
188		return NULL;
189
190	if ( (kv = BN_new()) == NULL ||
191		(gb = BN_new()) == NULL ||
192		(B = BN_new())== NULL)
193		goto err;
194
195	/* B = g**b + k*v */
196
197	if (!BN_mod_exp(gb,g,b,N,bn_ctx) ||
198	   !(k = srp_Calc_k(N,g)) ||
199	   !BN_mod_mul(kv,v,k,N,bn_ctx) ||
200	   !BN_mod_add(B,gb,kv,N,bn_ctx))
201		{
202		BN_free(B);
203		B = NULL;
204		}
205err:
206	BN_CTX_free(bn_ctx);
207	BN_clear_free(kv);
208	BN_clear_free(gb);
209	BN_free(k);
210	return B;
211	}
212
213BIGNUM *SRP_Calc_x(BIGNUM *s, const char *user, const char *pass)
214	{
215	unsigned char dig[SHA_DIGEST_LENGTH];
216	EVP_MD_CTX ctxt;
217	unsigned char *cs;
218
219	if ((s == NULL) ||
220		(user == NULL) ||
221		(pass == NULL))
222		return NULL;
223
224	if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
225		return NULL;
226
227	EVP_MD_CTX_init(&ctxt);
228	EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
229	EVP_DigestUpdate(&ctxt, user, strlen(user));
230	EVP_DigestUpdate(&ctxt, ":", 1);
231	EVP_DigestUpdate(&ctxt, pass, strlen(pass));
232	EVP_DigestFinal_ex(&ctxt, dig, NULL);
233
234	EVP_DigestInit_ex(&ctxt, EVP_sha1(), NULL);
235	BN_bn2bin(s,cs);
236	EVP_DigestUpdate(&ctxt, cs, BN_num_bytes(s));
237	OPENSSL_free(cs);
238	EVP_DigestUpdate(&ctxt, dig, sizeof(dig));
239	EVP_DigestFinal_ex(&ctxt, dig, NULL);
240	EVP_MD_CTX_cleanup(&ctxt);
241
242	return BN_bin2bn(dig, sizeof(dig), NULL);
243	}
244
245BIGNUM *SRP_Calc_A(BIGNUM *a, BIGNUM *N, BIGNUM *g)
246	{
247	BN_CTX *bn_ctx;
248	BIGNUM * A = NULL;
249
250	if (a == NULL || N == NULL || g == NULL ||
251		(bn_ctx = BN_CTX_new()) == NULL)
252		return NULL;
253
254	if ((A = BN_new()) != NULL &&
255	   !BN_mod_exp(A,g,a,N,bn_ctx))
256		{
257		BN_free(A);
258		A = NULL;
259		}
260	BN_CTX_free(bn_ctx);
261	return A;
262	}
263
264
265BIGNUM *SRP_Calc_client_key(BIGNUM *N, BIGNUM *B, BIGNUM *g, BIGNUM *x, BIGNUM *a, BIGNUM *u)
266	{
267	BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL , *k = NULL, *K = NULL;
268	BN_CTX *bn_ctx;
269
270	if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL || a == NULL ||
271		(bn_ctx = BN_CTX_new()) == NULL)
272		return NULL;
273
274	if ((tmp = BN_new()) == NULL ||
275		(tmp2 = BN_new())== NULL ||
276		(tmp3 = BN_new())== NULL ||
277		(K = BN_new()) == NULL)
278		goto err;
279
280	if (!BN_mod_exp(tmp,g,x,N,bn_ctx))
281		goto err;
282	if (!(k = srp_Calc_k(N,g)))
283		goto err;
284	if (!BN_mod_mul(tmp2,tmp,k,N,bn_ctx))
285		goto err;
286	if (!BN_mod_sub(tmp,B,tmp2,N,bn_ctx))
287		goto err;
288
289	if (!BN_mod_mul(tmp3,u,x,N,bn_ctx))
290		goto err;
291	if (!BN_mod_add(tmp2,a,tmp3,N,bn_ctx))
292		goto err;
293	if (!BN_mod_exp(K,tmp,tmp2,N,bn_ctx))
294		goto err;
295
296err :
297	BN_CTX_free(bn_ctx);
298	BN_clear_free(tmp);
299	BN_clear_free(tmp2);
300	BN_clear_free(tmp3);
301	BN_free(k);
302	return K;
303	}
304
305int SRP_Verify_B_mod_N(BIGNUM *B, BIGNUM *N)
306	{
307	BIGNUM *r;
308	BN_CTX *bn_ctx;
309	int ret = 0;
310
311	if (B == NULL || N == NULL ||
312		(bn_ctx = BN_CTX_new()) == NULL)
313		return 0;
314
315	if ((r = BN_new()) == NULL)
316		goto err;
317	/* Checks if B % N == 0 */
318	if (!BN_nnmod(r,B,N,bn_ctx))
319		goto err;
320	ret = !BN_is_zero(r);
321err:
322	BN_CTX_free(bn_ctx);
323	BN_free(r);
324	return ret;
325	}
326
327int SRP_Verify_A_mod_N(BIGNUM *A, BIGNUM *N)
328	{
329	/* Checks if A % N == 0 */
330	return SRP_Verify_B_mod_N(A,N) ;
331	}
332
333
334/* Check if G and N are kwown parameters.
335   The values have been generated from the ietf-tls-srp draft version 8
336*/
337char *SRP_check_known_gN_param(BIGNUM *g, BIGNUM *N)
338	{
339	size_t i;
340	if ((g == NULL) || (N == NULL))
341		return 0;
342
343	srp_bn_print(g);
344	srp_bn_print(N);
345
346	for(i = 0; i < KNOWN_GN_NUMBER; i++)
347		{
348		if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
349			return knowngN[i].id;
350		}
351	return NULL;
352	}
353
354SRP_gN *SRP_get_default_gN(const char *id)
355	{
356	size_t i;
357
358	if (id == NULL)
359		return knowngN;
360	for(i = 0; i < KNOWN_GN_NUMBER; i++)
361		{
362		if (strcmp(knowngN[i].id, id)==0)
363			return knowngN + i;
364		}
365	return NULL;
366	}
367#endif
368