1 | /* |
2 | * Copyright 2004-2018 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 | #ifndef OPENSSL_NO_SRP |
15 | # include "internal/cryptlib.h" |
16 | # include <openssl/sha.h> |
17 | # include <openssl/srp.h> |
18 | # include <openssl/evp.h> |
19 | # include "crypto/bn_srp.h" |
20 | |
21 | /* calculate = SHA1(PAD(x) || PAD(y)) */ |
22 | |
23 | static BIGNUM *srp_Calc_xy(const BIGNUM *x, const BIGNUM *y, const BIGNUM *N) |
24 | { |
25 | unsigned char digest[SHA_DIGEST_LENGTH]; |
26 | unsigned char *tmp = NULL; |
27 | int numN = BN_num_bytes(N); |
28 | BIGNUM *res = NULL; |
29 | |
30 | if (x != N && BN_ucmp(x, N) >= 0) |
31 | return NULL; |
32 | if (y != N && BN_ucmp(y, N) >= 0) |
33 | return NULL; |
34 | if ((tmp = OPENSSL_malloc(numN * 2)) == NULL) |
35 | goto err; |
36 | if (BN_bn2binpad(x, tmp, numN) < 0 |
37 | || BN_bn2binpad(y, tmp + numN, numN) < 0 |
38 | || !EVP_Digest(tmp, numN * 2, digest, NULL, EVP_sha1(), NULL)) |
39 | goto err; |
40 | res = BN_bin2bn(digest, sizeof(digest), NULL); |
41 | err: |
42 | OPENSSL_free(tmp); |
43 | return res; |
44 | } |
45 | |
46 | static BIGNUM *srp_Calc_k(const BIGNUM *N, const BIGNUM *g) |
47 | { |
48 | /* k = SHA1(N | PAD(g)) -- tls-srp RFC 5054 */ |
49 | return srp_Calc_xy(N, g, N); |
50 | } |
51 | |
52 | BIGNUM *SRP_Calc_u(const BIGNUM *A, const BIGNUM *B, const BIGNUM *N) |
53 | { |
54 | /* u = SHA1(PAD(A) || PAD(B) ) -- tls-srp RFC 5054 */ |
55 | return srp_Calc_xy(A, B, N); |
56 | } |
57 | |
58 | BIGNUM *SRP_Calc_server_key(const BIGNUM *A, const BIGNUM *v, const BIGNUM *u, |
59 | const BIGNUM *b, const BIGNUM *N) |
60 | { |
61 | BIGNUM *tmp = NULL, *S = NULL; |
62 | BN_CTX *bn_ctx; |
63 | |
64 | if (u == NULL || A == NULL || v == NULL || b == NULL || N == NULL) |
65 | return NULL; |
66 | |
67 | if ((bn_ctx = BN_CTX_new()) == NULL || (tmp = BN_new()) == NULL) |
68 | goto err; |
69 | |
70 | /* S = (A*v**u) ** b */ |
71 | |
72 | if (!BN_mod_exp(tmp, v, u, N, bn_ctx)) |
73 | goto err; |
74 | if (!BN_mod_mul(tmp, A, tmp, N, bn_ctx)) |
75 | goto err; |
76 | |
77 | S = BN_new(); |
78 | if (S != NULL && !BN_mod_exp(S, tmp, b, N, bn_ctx)) { |
79 | BN_free(S); |
80 | S = NULL; |
81 | } |
82 | err: |
83 | BN_CTX_free(bn_ctx); |
84 | BN_clear_free(tmp); |
85 | return S; |
86 | } |
87 | |
88 | BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g, |
89 | const BIGNUM *v) |
90 | { |
91 | BIGNUM *kv = NULL, *gb = NULL; |
92 | BIGNUM *B = NULL, *k = NULL; |
93 | BN_CTX *bn_ctx; |
94 | |
95 | if (b == NULL || N == NULL || g == NULL || v == NULL || |
96 | (bn_ctx = BN_CTX_new()) == NULL) |
97 | return NULL; |
98 | |
99 | if ((kv = BN_new()) == NULL || |
100 | (gb = BN_new()) == NULL || (B = BN_new()) == NULL) |
101 | goto err; |
102 | |
103 | /* B = g**b + k*v */ |
104 | |
105 | if (!BN_mod_exp(gb, g, b, N, bn_ctx) |
106 | || (k = srp_Calc_k(N, g)) == NULL |
107 | || !BN_mod_mul(kv, v, k, N, bn_ctx) |
108 | || !BN_mod_add(B, gb, kv, N, bn_ctx)) { |
109 | BN_free(B); |
110 | B = NULL; |
111 | } |
112 | err: |
113 | BN_CTX_free(bn_ctx); |
114 | BN_clear_free(kv); |
115 | BN_clear_free(gb); |
116 | BN_free(k); |
117 | return B; |
118 | } |
119 | |
120 | BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass) |
121 | { |
122 | unsigned char dig[SHA_DIGEST_LENGTH]; |
123 | EVP_MD_CTX *ctxt; |
124 | unsigned char *cs = NULL; |
125 | BIGNUM *res = NULL; |
126 | |
127 | if ((s == NULL) || (user == NULL) || (pass == NULL)) |
128 | return NULL; |
129 | |
130 | ctxt = EVP_MD_CTX_new(); |
131 | if (ctxt == NULL) |
132 | return NULL; |
133 | if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL) |
134 | goto err; |
135 | |
136 | if (!EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL) |
137 | || !EVP_DigestUpdate(ctxt, user, strlen(user)) |
138 | || !EVP_DigestUpdate(ctxt, ":" , 1) |
139 | || !EVP_DigestUpdate(ctxt, pass, strlen(pass)) |
140 | || !EVP_DigestFinal_ex(ctxt, dig, NULL) |
141 | || !EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL)) |
142 | goto err; |
143 | if (BN_bn2bin(s, cs) < 0) |
144 | goto err; |
145 | if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s))) |
146 | goto err; |
147 | |
148 | if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig)) |
149 | || !EVP_DigestFinal_ex(ctxt, dig, NULL)) |
150 | goto err; |
151 | |
152 | res = BN_bin2bn(dig, sizeof(dig), NULL); |
153 | |
154 | err: |
155 | OPENSSL_free(cs); |
156 | EVP_MD_CTX_free(ctxt); |
157 | return res; |
158 | } |
159 | |
160 | BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g) |
161 | { |
162 | BN_CTX *bn_ctx; |
163 | BIGNUM *A = NULL; |
164 | |
165 | if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL) |
166 | return NULL; |
167 | |
168 | if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) { |
169 | BN_free(A); |
170 | A = NULL; |
171 | } |
172 | BN_CTX_free(bn_ctx); |
173 | return A; |
174 | } |
175 | |
176 | BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g, |
177 | const BIGNUM *x, const BIGNUM *a, const BIGNUM *u) |
178 | { |
179 | BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL; |
180 | BN_CTX *bn_ctx; |
181 | |
182 | if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL |
183 | || a == NULL || (bn_ctx = BN_CTX_new()) == NULL) |
184 | return NULL; |
185 | |
186 | if ((tmp = BN_new()) == NULL || |
187 | (tmp2 = BN_new()) == NULL || |
188 | (tmp3 = BN_new()) == NULL) |
189 | goto err; |
190 | |
191 | if (!BN_mod_exp(tmp, g, x, N, bn_ctx)) |
192 | goto err; |
193 | if ((k = srp_Calc_k(N, g)) == NULL) |
194 | goto err; |
195 | if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx)) |
196 | goto err; |
197 | if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx)) |
198 | goto err; |
199 | if (!BN_mul(tmp3, u, x, bn_ctx)) |
200 | goto err; |
201 | if (!BN_add(tmp2, a, tmp3)) |
202 | goto err; |
203 | K = BN_new(); |
204 | if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) { |
205 | BN_free(K); |
206 | K = NULL; |
207 | } |
208 | |
209 | err: |
210 | BN_CTX_free(bn_ctx); |
211 | BN_clear_free(tmp); |
212 | BN_clear_free(tmp2); |
213 | BN_clear_free(tmp3); |
214 | BN_free(k); |
215 | return K; |
216 | } |
217 | |
218 | int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N) |
219 | { |
220 | BIGNUM *r; |
221 | BN_CTX *bn_ctx; |
222 | int ret = 0; |
223 | |
224 | if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL) |
225 | return 0; |
226 | |
227 | if ((r = BN_new()) == NULL) |
228 | goto err; |
229 | /* Checks if B % N == 0 */ |
230 | if (!BN_nnmod(r, B, N, bn_ctx)) |
231 | goto err; |
232 | ret = !BN_is_zero(r); |
233 | err: |
234 | BN_CTX_free(bn_ctx); |
235 | BN_free(r); |
236 | return ret; |
237 | } |
238 | |
239 | int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N) |
240 | { |
241 | /* Checks if A % N == 0 */ |
242 | return SRP_Verify_B_mod_N(A, N); |
243 | } |
244 | |
245 | static SRP_gN knowngN[] = { |
246 | {"8192" , &bn_generator_19, &bn_group_8192}, |
247 | {"6144" , &bn_generator_5, &bn_group_6144}, |
248 | {"4096" , &bn_generator_5, &bn_group_4096}, |
249 | {"3072" , &bn_generator_5, &bn_group_3072}, |
250 | {"2048" , &bn_generator_2, &bn_group_2048}, |
251 | {"1536" , &bn_generator_2, &bn_group_1536}, |
252 | {"1024" , &bn_generator_2, &bn_group_1024}, |
253 | }; |
254 | |
255 | # define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN) |
256 | |
257 | /* |
258 | * Check if G and N are known parameters. The values have been generated |
259 | * from the IETF RFC 5054 |
260 | */ |
261 | char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N) |
262 | { |
263 | size_t i; |
264 | if ((g == NULL) || (N == NULL)) |
265 | return NULL; |
266 | |
267 | for (i = 0; i < KNOWN_GN_NUMBER; i++) { |
268 | if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0) |
269 | return knowngN[i].id; |
270 | } |
271 | return NULL; |
272 | } |
273 | |
274 | SRP_gN *SRP_get_default_gN(const char *id) |
275 | { |
276 | size_t i; |
277 | |
278 | if (id == NULL) |
279 | return knowngN; |
280 | for (i = 0; i < KNOWN_GN_NUMBER; i++) { |
281 | if (strcmp(knowngN[i].id, id) == 0) |
282 | return knowngN + i; |
283 | } |
284 | return NULL; |
285 | } |
286 | #endif |
287 | |