1 | /* |
2 | * Copyright 1998-2018 The OpenSSL Project Authors. All Rights Reserved. |
3 | * |
4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at |
7 | * https://www.openssl.org/source/license.html |
8 | */ |
9 | |
10 | #include <openssl/opensslconf.h> |
11 | #include "internal/cryptlib.h" |
12 | #include "bn_local.h" |
13 | |
14 | #define BN_BLINDING_COUNTER 32 |
15 | |
16 | struct bn_blinding_st { |
17 | BIGNUM *A; |
18 | BIGNUM *Ai; |
19 | BIGNUM *e; |
20 | BIGNUM *mod; /* just a reference */ |
21 | CRYPTO_THREAD_ID tid; |
22 | int counter; |
23 | unsigned long flags; |
24 | BN_MONT_CTX *m_ctx; |
25 | int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p, |
26 | const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); |
27 | CRYPTO_RWLOCK *lock; |
28 | }; |
29 | |
30 | BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod) |
31 | { |
32 | BN_BLINDING *ret = NULL; |
33 | |
34 | bn_check_top(mod); |
35 | |
36 | if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) { |
37 | BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE); |
38 | return NULL; |
39 | } |
40 | |
41 | ret->lock = CRYPTO_THREAD_lock_new(); |
42 | if (ret->lock == NULL) { |
43 | BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE); |
44 | OPENSSL_free(ret); |
45 | return NULL; |
46 | } |
47 | |
48 | BN_BLINDING_set_current_thread(ret); |
49 | |
50 | if (A != NULL) { |
51 | if ((ret->A = BN_dup(A)) == NULL) |
52 | goto err; |
53 | } |
54 | |
55 | if (Ai != NULL) { |
56 | if ((ret->Ai = BN_dup(Ai)) == NULL) |
57 | goto err; |
58 | } |
59 | |
60 | /* save a copy of mod in the BN_BLINDING structure */ |
61 | if ((ret->mod = BN_dup(mod)) == NULL) |
62 | goto err; |
63 | |
64 | if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0) |
65 | BN_set_flags(ret->mod, BN_FLG_CONSTTIME); |
66 | |
67 | /* |
68 | * Set the counter to the special value -1 to indicate that this is |
69 | * never-used fresh blinding that does not need updating before first |
70 | * use. |
71 | */ |
72 | ret->counter = -1; |
73 | |
74 | return ret; |
75 | |
76 | err: |
77 | BN_BLINDING_free(ret); |
78 | return NULL; |
79 | } |
80 | |
81 | void BN_BLINDING_free(BN_BLINDING *r) |
82 | { |
83 | if (r == NULL) |
84 | return; |
85 | BN_free(r->A); |
86 | BN_free(r->Ai); |
87 | BN_free(r->e); |
88 | BN_free(r->mod); |
89 | CRYPTO_THREAD_lock_free(r->lock); |
90 | OPENSSL_free(r); |
91 | } |
92 | |
93 | int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx) |
94 | { |
95 | int ret = 0; |
96 | |
97 | if ((b->A == NULL) || (b->Ai == NULL)) { |
98 | BNerr(BN_F_BN_BLINDING_UPDATE, BN_R_NOT_INITIALIZED); |
99 | goto err; |
100 | } |
101 | |
102 | if (b->counter == -1) |
103 | b->counter = 0; |
104 | |
105 | if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL && |
106 | !(b->flags & BN_BLINDING_NO_RECREATE)) { |
107 | /* re-create blinding parameters */ |
108 | if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL)) |
109 | goto err; |
110 | } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) { |
111 | if (b->m_ctx != NULL) { |
112 | if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx) |
113 | || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx)) |
114 | goto err; |
115 | } else { |
116 | if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx) |
117 | || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx)) |
118 | goto err; |
119 | } |
120 | } |
121 | |
122 | ret = 1; |
123 | err: |
124 | if (b->counter == BN_BLINDING_COUNTER) |
125 | b->counter = 0; |
126 | return ret; |
127 | } |
128 | |
129 | int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx) |
130 | { |
131 | return BN_BLINDING_convert_ex(n, NULL, b, ctx); |
132 | } |
133 | |
134 | int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx) |
135 | { |
136 | int ret = 1; |
137 | |
138 | bn_check_top(n); |
139 | |
140 | if ((b->A == NULL) || (b->Ai == NULL)) { |
141 | BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED); |
142 | return 0; |
143 | } |
144 | |
145 | if (b->counter == -1) |
146 | /* Fresh blinding, doesn't need updating. */ |
147 | b->counter = 0; |
148 | else if (!BN_BLINDING_update(b, ctx)) |
149 | return 0; |
150 | |
151 | if (r != NULL && (BN_copy(r, b->Ai) == NULL)) |
152 | return 0; |
153 | |
154 | if (b->m_ctx != NULL) |
155 | ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx); |
156 | else |
157 | ret = BN_mod_mul(n, n, b->A, b->mod, ctx); |
158 | |
159 | return ret; |
160 | } |
161 | |
162 | int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx) |
163 | { |
164 | return BN_BLINDING_invert_ex(n, NULL, b, ctx); |
165 | } |
166 | |
167 | int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b, |
168 | BN_CTX *ctx) |
169 | { |
170 | int ret; |
171 | |
172 | bn_check_top(n); |
173 | |
174 | if (r == NULL && (r = b->Ai) == NULL) { |
175 | BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED); |
176 | return 0; |
177 | } |
178 | |
179 | if (b->m_ctx != NULL) { |
180 | /* ensure that BN_mod_mul_montgomery takes pre-defined path */ |
181 | if (n->dmax >= r->top) { |
182 | size_t i, rtop = r->top, ntop = n->top; |
183 | BN_ULONG mask; |
184 | |
185 | for (i = 0; i < rtop; i++) { |
186 | mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1)); |
187 | n->d[i] &= mask; |
188 | } |
189 | mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1)); |
190 | /* always true, if (rtop >= ntop) n->top = r->top; */ |
191 | n->top = (int)(rtop & ~mask) | (ntop & mask); |
192 | n->flags |= (BN_FLG_FIXED_TOP & ~mask); |
193 | } |
194 | ret = BN_mod_mul_montgomery(n, n, r, b->m_ctx, ctx); |
195 | } else { |
196 | ret = BN_mod_mul(n, n, r, b->mod, ctx); |
197 | } |
198 | |
199 | bn_check_top(n); |
200 | return ret; |
201 | } |
202 | |
203 | int BN_BLINDING_is_current_thread(BN_BLINDING *b) |
204 | { |
205 | return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid); |
206 | } |
207 | |
208 | void BN_BLINDING_set_current_thread(BN_BLINDING *b) |
209 | { |
210 | b->tid = CRYPTO_THREAD_get_current_id(); |
211 | } |
212 | |
213 | int BN_BLINDING_lock(BN_BLINDING *b) |
214 | { |
215 | return CRYPTO_THREAD_write_lock(b->lock); |
216 | } |
217 | |
218 | int BN_BLINDING_unlock(BN_BLINDING *b) |
219 | { |
220 | return CRYPTO_THREAD_unlock(b->lock); |
221 | } |
222 | |
223 | unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b) |
224 | { |
225 | return b->flags; |
226 | } |
227 | |
228 | void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags) |
229 | { |
230 | b->flags = flags; |
231 | } |
232 | |
233 | BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b, |
234 | const BIGNUM *e, BIGNUM *m, BN_CTX *ctx, |
235 | int (*bn_mod_exp) (BIGNUM *r, |
236 | const BIGNUM *a, |
237 | const BIGNUM *p, |
238 | const BIGNUM *m, |
239 | BN_CTX *ctx, |
240 | BN_MONT_CTX *m_ctx), |
241 | BN_MONT_CTX *m_ctx) |
242 | { |
243 | int retry_counter = 32; |
244 | BN_BLINDING *ret = NULL; |
245 | |
246 | if (b == NULL) |
247 | ret = BN_BLINDING_new(NULL, NULL, m); |
248 | else |
249 | ret = b; |
250 | |
251 | if (ret == NULL) |
252 | goto err; |
253 | |
254 | if (ret->A == NULL && (ret->A = BN_new()) == NULL) |
255 | goto err; |
256 | if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL) |
257 | goto err; |
258 | |
259 | if (e != NULL) { |
260 | BN_free(ret->e); |
261 | ret->e = BN_dup(e); |
262 | } |
263 | if (ret->e == NULL) |
264 | goto err; |
265 | |
266 | if (bn_mod_exp != NULL) |
267 | ret->bn_mod_exp = bn_mod_exp; |
268 | if (m_ctx != NULL) |
269 | ret->m_ctx = m_ctx; |
270 | |
271 | do { |
272 | int rv; |
273 | if (!BN_priv_rand_range_ex(ret->A, ret->mod, ctx)) |
274 | goto err; |
275 | if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv)) |
276 | break; |
277 | |
278 | /* |
279 | * this should almost never happen for good RSA keys |
280 | */ |
281 | if (!rv) |
282 | goto err; |
283 | |
284 | if (retry_counter-- == 0) { |
285 | BNerr(BN_F_BN_BLINDING_CREATE_PARAM, BN_R_TOO_MANY_ITERATIONS); |
286 | goto err; |
287 | } |
288 | } while (1); |
289 | |
290 | if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) { |
291 | if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx)) |
292 | goto err; |
293 | } else { |
294 | if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx)) |
295 | goto err; |
296 | } |
297 | |
298 | if (ret->m_ctx != NULL) { |
299 | if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx) |
300 | || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx)) |
301 | goto err; |
302 | } |
303 | |
304 | return ret; |
305 | err: |
306 | if (b == NULL) { |
307 | BN_BLINDING_free(ret); |
308 | ret = NULL; |
309 | } |
310 | |
311 | return ret; |
312 | } |
313 | |