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