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 || (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
114 return NULL;
115
116 if ((kv = BN_new()) == NULL || (gb = BN_new()) == NULL || (B = BN_new()) == NULL)
117 goto err;
118
119 /* B = g**b + k*v */
120
121 if (!BN_mod_exp(gb, g, b, N, bn_ctx)
122 || (k = srp_Calc_k(N, g, libctx, propq)) == NULL
123 || !BN_mod_mul(kv, v, k, N, bn_ctx)
124 || !BN_mod_add(B, gb, kv, N, bn_ctx)) {
125 BN_free(B);
126 B = NULL;
127 }
128 err:
129 BN_CTX_free(bn_ctx);
130 BN_clear_free(kv);
131 BN_clear_free(gb);
132 BN_free(k);
133 return B;
134 }
135
SRP_Calc_B(const BIGNUM * b,const BIGNUM * N,const BIGNUM * g,const BIGNUM * v)136 BIGNUM *SRP_Calc_B(const BIGNUM *b, const BIGNUM *N, const BIGNUM *g,
137 const BIGNUM *v)
138 {
139 return SRP_Calc_B_ex(b, N, g, v, NULL, NULL);
140 }
141
SRP_Calc_x_ex(const BIGNUM * s,const char * user,const char * pass,OSSL_LIB_CTX * libctx,const char * propq)142 BIGNUM *SRP_Calc_x_ex(const BIGNUM *s, const char *user, const char *pass,
143 OSSL_LIB_CTX *libctx, const char *propq)
144 {
145 unsigned char dig[SHA_DIGEST_LENGTH];
146 EVP_MD_CTX *ctxt;
147 unsigned char *cs = NULL;
148 BIGNUM *res = NULL;
149 EVP_MD *sha1 = NULL;
150
151 if ((s == NULL) || (user == NULL) || (pass == NULL))
152 return NULL;
153
154 ctxt = EVP_MD_CTX_new();
155 if (ctxt == NULL)
156 return NULL;
157 if ((cs = OPENSSL_malloc(BN_num_bytes(s))) == NULL)
158 goto err;
159
160 sha1 = EVP_MD_fetch(libctx, "SHA1", propq);
161 if (sha1 == NULL)
162 goto err;
163
164 if (!EVP_DigestInit_ex(ctxt, sha1, NULL)
165 || !EVP_DigestUpdate(ctxt, user, strlen(user))
166 || !EVP_DigestUpdate(ctxt, ":", 1)
167 || !EVP_DigestUpdate(ctxt, pass, strlen(pass))
168 || !EVP_DigestFinal_ex(ctxt, dig, NULL)
169 || !EVP_DigestInit_ex(ctxt, sha1, NULL))
170 goto err;
171 if (BN_bn2bin(s, cs) < 0)
172 goto err;
173 if (!EVP_DigestUpdate(ctxt, cs, BN_num_bytes(s)))
174 goto err;
175
176 if (!EVP_DigestUpdate(ctxt, dig, sizeof(dig))
177 || !EVP_DigestFinal_ex(ctxt, dig, NULL))
178 goto err;
179
180 res = BN_bin2bn(dig, sizeof(dig), NULL);
181
182 err:
183 EVP_MD_free(sha1);
184 OPENSSL_free(cs);
185 EVP_MD_CTX_free(ctxt);
186 return res;
187 }
188
SRP_Calc_x(const BIGNUM * s,const char * user,const char * pass)189 BIGNUM *SRP_Calc_x(const BIGNUM *s, const char *user, const char *pass)
190 {
191 return SRP_Calc_x_ex(s, user, pass, NULL, NULL);
192 }
193
SRP_Calc_A(const BIGNUM * a,const BIGNUM * N,const BIGNUM * g)194 BIGNUM *SRP_Calc_A(const BIGNUM *a, const BIGNUM *N, const BIGNUM *g)
195 {
196 BN_CTX *bn_ctx;
197 BIGNUM *A = NULL;
198
199 if (a == NULL || N == NULL || g == NULL || (bn_ctx = BN_CTX_new()) == NULL)
200 return NULL;
201
202 if ((A = BN_new()) != NULL && !BN_mod_exp(A, g, a, N, bn_ctx)) {
203 BN_free(A);
204 A = NULL;
205 }
206 BN_CTX_free(bn_ctx);
207 return A;
208 }
209
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)210 BIGNUM *SRP_Calc_client_key_ex(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
211 const BIGNUM *x, const BIGNUM *a, const BIGNUM *u,
212 OSSL_LIB_CTX *libctx, const char *propq)
213 {
214 BIGNUM *tmp = NULL, *tmp2 = NULL, *tmp3 = NULL, *k = NULL, *K = NULL;
215 BIGNUM *xtmp = NULL;
216 BN_CTX *bn_ctx;
217
218 if (u == NULL || B == NULL || N == NULL || g == NULL || x == NULL
219 || a == NULL || (bn_ctx = BN_CTX_new_ex(libctx)) == NULL)
220 return NULL;
221
222 if ((tmp = BN_new()) == NULL || (tmp2 = BN_new()) == NULL || (tmp3 = BN_new()) == NULL || (xtmp = BN_new()) == NULL)
223 goto err;
224
225 BN_with_flags(xtmp, x, BN_FLG_CONSTTIME);
226 BN_set_flags(tmp, BN_FLG_CONSTTIME);
227 if (!BN_mod_exp(tmp, g, xtmp, N, bn_ctx))
228 goto err;
229 if ((k = srp_Calc_k(N, g, libctx, propq)) == NULL)
230 goto err;
231 if (!BN_mod_mul(tmp2, tmp, k, N, bn_ctx))
232 goto err;
233 if (!BN_mod_sub(tmp, B, tmp2, N, bn_ctx))
234 goto err;
235 if (!BN_mul(tmp3, u, xtmp, bn_ctx))
236 goto err;
237 if (!BN_add(tmp2, a, tmp3))
238 goto err;
239 K = BN_new();
240 if (K != NULL && !BN_mod_exp(K, tmp, tmp2, N, bn_ctx)) {
241 BN_free(K);
242 K = NULL;
243 }
244
245 err:
246 BN_CTX_free(bn_ctx);
247 BN_free(xtmp);
248 BN_clear_free(tmp);
249 BN_clear_free(tmp2);
250 BN_clear_free(tmp3);
251 BN_free(k);
252 return K;
253 }
254
SRP_Calc_client_key(const BIGNUM * N,const BIGNUM * B,const BIGNUM * g,const BIGNUM * x,const BIGNUM * a,const BIGNUM * u)255 BIGNUM *SRP_Calc_client_key(const BIGNUM *N, const BIGNUM *B, const BIGNUM *g,
256 const BIGNUM *x, const BIGNUM *a, const BIGNUM *u)
257 {
258 return SRP_Calc_client_key_ex(N, B, g, x, a, u, NULL, NULL);
259 }
260
SRP_Verify_B_mod_N(const BIGNUM * B,const BIGNUM * N)261 int SRP_Verify_B_mod_N(const BIGNUM *B, const BIGNUM *N)
262 {
263 BIGNUM *r;
264 BN_CTX *bn_ctx;
265 int ret = 0;
266
267 if (B == NULL || N == NULL || (bn_ctx = BN_CTX_new()) == NULL)
268 return 0;
269
270 if ((r = BN_new()) == NULL)
271 goto err;
272 /* Checks if B % N == 0 */
273 if (!BN_nnmod(r, B, N, bn_ctx))
274 goto err;
275 ret = !BN_is_zero(r);
276 err:
277 BN_CTX_free(bn_ctx);
278 BN_free(r);
279 return ret;
280 }
281
SRP_Verify_A_mod_N(const BIGNUM * A,const BIGNUM * N)282 int SRP_Verify_A_mod_N(const BIGNUM *A, const BIGNUM *N)
283 {
284 /* Checks if A % N == 0 */
285 return SRP_Verify_B_mod_N(A, N);
286 }
287
288 static SRP_gN knowngN[] = {
289 { "8192", &ossl_bn_generator_19, &ossl_bn_group_8192 },
290 { "6144", &ossl_bn_generator_5, &ossl_bn_group_6144 },
291 { "4096", &ossl_bn_generator_5, &ossl_bn_group_4096 },
292 { "3072", &ossl_bn_generator_5, &ossl_bn_group_3072 },
293 { "2048", &ossl_bn_generator_2, &ossl_bn_group_2048 },
294 { "1536", &ossl_bn_generator_2, &ossl_bn_group_1536 },
295 { "1024", &ossl_bn_generator_2, &ossl_bn_group_1024 },
296 };
297
298 #define KNOWN_GN_NUMBER sizeof(knowngN) / sizeof(SRP_gN)
299
300 /*
301 * Check if G and N are known parameters. The values have been generated
302 * from the IETF RFC 5054
303 */
SRP_check_known_gN_param(const BIGNUM * g,const BIGNUM * N)304 char *SRP_check_known_gN_param(const BIGNUM *g, const BIGNUM *N)
305 {
306 size_t i;
307 if ((g == NULL) || (N == NULL))
308 return NULL;
309
310 for (i = 0; i < KNOWN_GN_NUMBER; i++) {
311 if (BN_cmp(knowngN[i].g, g) == 0 && BN_cmp(knowngN[i].N, N) == 0)
312 return knowngN[i].id;
313 }
314 return NULL;
315 }
316
SRP_get_default_gN(const char * id)317 SRP_gN *SRP_get_default_gN(const char *id)
318 {
319 size_t i;
320
321 if (id == NULL)
322 return knowngN;
323 for (i = 0; i < KNOWN_GN_NUMBER; i++) {
324 if (strcmp(knowngN[i].id, id) == 0)
325 return knowngN + i;
326 }
327 return NULL;
328 }
329 #endif
330