1 /*
2 * Copyright 2004-2021 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2004, EdelKey Project. All Rights Reserved.
4 *
5 * Licensed under the Apache License 2.0 (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 *
10 * Originally written by Christophe Renou and Peter Sylvester,
11 * for the EdelKey project.
12 */
13
14 /* All the SRP APIs in this file are deprecated */
15 #define OPENSSL_SUPPRESS_DEPRECATED
16
17 #ifndef OPENSSL_NO_SRP
18 # include "internal/cryptlib.h"
19 # include <openssl/sha.h>
20 # include <openssl/srp.h>
21 # include <openssl/evp.h>
22 # include "crypto/bn_srp.h"
23
24 /* calculate = SHA1(PAD(x) || PAD(y)) */
25
srp_Calc_xy(const BIGNUM * x,const BIGNUM * y,const BIGNUM * N,OSSL_LIB_CTX * libctx,const char * propq)26 static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N,
27 OSSL_LIB_CTX *libctx, const char *propq)
28 {
29 unsigned char digest[SHA_DIGEST_LENGTH];
30 unsigned char *tmp = NULL;
31 int numN = BN_num_bytes(N);
32 BIGNUM *res = NULL;
33 EVP_MD *sha1 = EVP_MD_fetch(libctx, "SHA1", propq);
34
35 if (sha1 == NULL)
36 return NULL;
37
38 if (x != N && BN_ucmp(x, N) >= 0)
39 goto err;
40 if (y != N && BN_ucmp(y, N) >= 0)
41 goto err;
42 if ((tmp = OPENSSL_malloc(numN * 2)) == NULL)
43 goto err;
44 if (BN_bn2binpad(x, tmp, numN) < 0
45 || BN_bn2binpad(y, tmp + numN, numN) < 0
46 || !EVP_Digest(tmp, numN * 2, digest, NULL, sha1, NULL))
47 goto err;
48 res = BN_bin2bn(digest, sizeof(digest), NULL);
49 err:
50 EVP_MD_free(sha1);
51 OPENSSL_free(tmp);
52 return res;
53 }
54
srp_Calc_k(const BIGNUM * N,const BIGNUM * g,OSSL_LIB_CTX * libctx,const char * propq)55 static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g,
56 OSSL_LIB_CTX *libctx,
57 const char *propq)
58 {
59 /* k = SHA1(N | PAD(g)) -- tls-srp RFC 5054 */
60 return srp_Calc_xy(N, g, N, libctx, propq);
61 }
62
SRP_Calc_u_ex(const BIGNUM * A,const BIGNUM * B,const BIGNUM * N,OSSL_LIB_CTX * libctx,const char * propq)63 BIGNUM *SRP_Calc_u_ex(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N,
64 OSSL_LIB_CTX *libctx, const char *propq)
65 {
66 /* u = SHA1(PAD(A) || PAD(B) ) -- tls-srp RFC 5054 */
67 return srp_Calc_xy(A, B, N, libctx, propq);
68 }
69
SRP_Calc_u(const BIGNUM * A,const BIGNUM * B,const BIGNUM * N)70 BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N)
71 {
72 /* u = SHA1(PAD(A) || PAD(B) ) -- tls-srp RFC 5054 */
73 return srp_Calc_xy(A, B, N, NULL, NULL);
74 }
75
SRP_Calc_server_key(const BIGNUM * A,const BIGNUM * v,const BIGNUM * u,const BIGNUM * b,const BIGNUM * N)76 BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u,
77 const BIGNUM *b, const BIGNUM *N)
78 {
79 BIGNUM *tmp = NULL, *S = NULL;
80 BN_CTX *bn_ctx;
81
82 if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL)
83 return NULL;
84
85 if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL)
86 goto err;
87
88 /* S = (A*v**u) ** b */
89
90 if (!BN_mod_exp(tmp, v, u, N, bn_ctx))
91 goto err;
92 if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx))
93 goto err;
94
95 S = BN_new();
96 if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) {
97 BN_free(S);
98 S = NULL;
99 }
100 err:
101 BN_CTX_free(bn_ctx);
102 BN_clear_free(tmp);
103 return S;
104 }
105
SRP_Calc_B_ex(const BIGNUM * b,const BIGNUM * N,const BIGNUM * g,const BIGNUM * v,OSSL_LIB_CTX * libctx,const char * propq)106 BIGNUM *SRP_Calc_B_ex(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
107 const BIGNUM *v, OSSL_LIB_CTX *libctx, const char *propq)
108 {
109 BIGNUM *kv = NULL, *gb = NULL;
110 BIGNUM *B = NULL, *k = NULL;
111 BN_CTX *bn_ctx;
112
113 if (b == NULL || N == NULL || g == NULL || v == NULL ||
114 (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
115 return NULL;
116
117 if ((kv = BN_new()) == NULL ||
118 (gb = BN_new()) == NULL || (B = BN_new()) == NULL)
119 goto err;
120
121 /* B = g**b + k*v */
122
123 if (!BN_mod_exp(gb, g, b, N, bn_ctx)
124 || (k = srp_Calc_k(N, g, libctx, propq)) == NULL
125 || !BN_mod_mul(kv, v, k, N, bn_ctx)
126 || !BN_mod_add(B, gb, kv, N, bn_ctx)) {
127 BN_free(B);
128 B = NULL;
129 }
130 err:
131 BN_CTX_free(bn_ctx);
132 BN_clear_free(kv);
133 BN_clear_free(gb);
134 BN_free(k);
135 return B;
136 }
137
SRP_Calc_B(const BIGNUM * b,const BIGNUM * N,const BIGNUM * g,const BIGNUM * v)138 BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
139 const BIGNUM *v)
140 {
141 return SRP_Calc_B_ex(b, N, g, v, NULL, NULL);
142 }
143
SRP_Calc_x_ex(const BIGNUM * s,const char * user,const char * pass,OSSL_LIB_CTX * libctx,const char * propq)144 BIGNUM *SRP_Calc_x_ex(const BIGNUM *s, const char *user, const char *pass,
145 OSSL_LIB_CTX *libctx, const char *propq)
146 {
147 unsigned char dig[SHA_DIGEST_LENGTH];
148 EVP_MD_CTX *ctxt;
149 unsigned char *cs = NULL;
150 BIGNUM *res = NULL;
151 EVP_MD *sha1 = NULL;
152
153 if ((s == NULL) || (user == NULL) || (pass == NULL))
154 return NULL;
155
156 ctxt = EVP_MD_CTX_new();
157 if (ctxt == NULL)
158 return NULL;
159 if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
160 goto err;
161
162 sha1 = EVP_MD_fetch(libctx, "SHA1", propq);
163 if (sha1 == NULL)
164 goto err;
165
166 if (!EVP_DigestInit_ex(ctxt, sha1, NULL)
167 || !EVP_DigestUpdate(ctxt, user, strlen(user))
168 || !EVP_DigestUpdate(ctxt, ":", 1)
169 || !EVP_DigestUpdate(ctxt, pass, strlen(pass))
170 || !EVP_DigestFinal_ex(ctxt, dig, NULL)
171 || !EVP_DigestInit_ex(ctxt, sha1, NULL))
172 goto err;
173 if (BN_bn2bin(s, cs) < 0)
174 goto err;
175 if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s)))
176 goto err;
177
178 if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig))
179 || !EVP_DigestFinal_ex(ctxt, dig, NULL))
180 goto err;
181
182 res = BN_bin2bn(dig, sizeof(dig), NULL);
183
184 err:
185 EVP_MD_free(sha1);
186 OPENSSL_free(cs);
187 EVP_MD_CTX_free(ctxt);
188 return res;
189 }
190
SRP_Calc_x(const BIGNUM * s,const char * user,const char * pass)191 BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass)
192 {
193 return SRP_Calc_x_ex(s, user, pass, NULL, NULL);
194 }
195
SRP_Calc_A(const BIGNUM * a,const BIGNUM * N,const BIGNUM * g)196 BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g)
197 {
198 BN_CTX *bn_ctx;
199 BIGNUM *A = NULL;
200
201 if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL)
202 return NULL;
203
204 if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
205 BN_free(A);
206 A = NULL;
207 }
208 BN_CTX_free(bn_ctx);
209 return A;
210 }
211
SRP_Calc_client_key_ex(const BIGNUM * N,const BIGNUM * B,const BIGNUM * g,const BIGNUM * x,const BIGNUM * a,const BIGNUM * u,OSSL_LIB_CTX * libctx,const char * propq)212 BIGNUM *SRP_Calc_client_key_ex(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
213 const BIGNUM *x, const BIGNUM *a, const BIGNUM *u,
214 OSSL_LIB_CTX *libctx, const char *propq)
215 {
216 BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
217 BIGNUM *xtmp = NULL;
218 BN_CTX *bn_ctx;
219
220 if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
221 || a == NULL || (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
222 return NULL;
223
224 if ((tmp = BN_new()) == NULL ||
225 (tmp2 = BN_new()) == NULL ||
226 (tmp3 = BN_new()) == NULL ||
227 (xtmp = BN_new()) == NULL)
228 goto err;
229
230 BN_with_flags(xtmp, x, BN_FLG_CONSTTIME);
231 BN_set_flags(tmp, BN_FLG_CONSTTIME);
232 if (!BN_mod_exp(tmp, g, xtmp, N, bn_ctx))
233 goto err;
234 if ((k = srp_Calc_k(N, g, libctx, propq)) == NULL)
235 goto err;
236 if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
237 goto err;
238 if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
239 goto err;
240 if (!BN_mul(tmp3, u, xtmp, bn_ctx))
241 goto err;
242 if (!BN_add(tmp2, a, tmp3))
243 goto err;
244 K = BN_new();
245 if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
246 BN_free(K);
247 K = NULL;
248 }
249
250 err:
251 BN_CTX_free(bn_ctx);
252 BN_free(xtmp);
253 BN_clear_free(tmp);
254 BN_clear_free(tmp2);
255 BN_clear_free(tmp3);
256 BN_free(k);
257 return K;
258 }
259
SRP_Calc_client_key(const BIGNUM * N,const BIGNUM * B,const BIGNUM * g,const BIGNUM * x,const BIGNUM * a,const BIGNUM * u)260 BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
261 const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
262 {
263 return SRP_Calc_client_key_ex(N, B, g, x, a, u, NULL, NULL);
264 }
265
SRP_Verify_B_mod_N(const BIGNUM * B,const BIGNUM * N)266 int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
267 {
268 BIGNUM *r;
269 BN_CTX *bn_ctx;
270 int ret = 0;
271
272 if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
273 return 0;
274
275 if ((r = BN_new()) == NULL)
276 goto err;
277 /* Checks if B % N == 0 */
278 if (!BN_nnmod(r, B, N, bn_ctx))
279 goto err;
280 ret = !BN_is_zero(r);
281 err:
282 BN_CTX_free(bn_ctx);
283 BN_free(r);
284 return ret;
285 }
286
SRP_Verify_A_mod_N(const BIGNUM * A,const BIGNUM * N)287 int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
288 {
289 /* Checks if A % N == 0 */
290 return SRP_Verify_B_mod_N(A, N);
291 }
292
293 static SRP_gN knowngN[] = {
294 {"8192", &ossl_bn_generator_19, &ossl_bn_group_8192},
295 {"6144", &ossl_bn_generator_5, &ossl_bn_group_6144},
296 {"4096", &ossl_bn_generator_5, &ossl_bn_group_4096},
297 {"3072", &ossl_bn_generator_5, &ossl_bn_group_3072},
298 {"2048", &ossl_bn_generator_2, &ossl_bn_group_2048},
299 {"1536", &ossl_bn_generator_2, &ossl_bn_group_1536},
300 {"1024", &ossl_bn_generator_2, &ossl_bn_group_1024},
301 };
302
303 # define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN)
304
305 /*
306 * Check if G and N are known parameters. The values have been generated
307 * from the IETF RFC 5054
308 */
SRP_check_known_gN_param(const BIGNUM * g,const BIGNUM * N)309 char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N)
310 {
311 size_t i;
312 if ((g == NULL) || (N == NULL))
313 return NULL;
314
315 for (i = 0; i < KNOWN_GN_NUMBER; i++) {
316 if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
317 return knowngN[i].id;
318 }
319 return NULL;
320 }
321
SRP_get_default_gN(const char * id)322 SRP_gN *SRP_get_default_gN(const char *id)
323 {
324 size_t i;
325
326 if (id == NULL)
327 return knowngN;
328 for (i = 0; i < KNOWN_GN_NUMBER; i++) {
329 if (strcmp(knowngN[i].id, id) == 0)
330 return knowngN + i;
331 }
332 return NULL;
333 }
334 #endif
335