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
26static 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
55static 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
63BIGNUM *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
70BIGNUM *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
76BIGNUM *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
106BIGNUM *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
138BIGNUM *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
144BIGNUM *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
191BIGNUM *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
196BIGNUM *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
212BIGNUM *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
260BIGNUM *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
266int 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
287int 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
293static 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 */
309char *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
322SRP_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