1 /* $OpenBSD: rsa_blinding.c,v 1.3 2023/08/09 12:09:06 tb Exp $ */
2 /* ====================================================================
3 * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 * software must display the following acknowledgment:
19 * "This product includes software developed by the OpenSSL Project
20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 * endorse or promote products derived from this software without
24 * prior written permission. For written permission, please contact
25 * openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 * nor may "OpenSSL" appear in their names without prior written
29 * permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 * acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 * This product includes cryptographic software written by Eric Young
51 * (eay@cryptsoft.com). This product includes software written by Tim
52 * Hudson (tjh@cryptsoft.com).
53 *
54 */
55 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
56 * All rights reserved.
57 *
58 * This package is an SSL implementation written
59 * by Eric Young (eay@cryptsoft.com).
60 * The implementation was written so as to conform with Netscapes SSL.
61 *
62 * This library is free for commercial and non-commercial use as long as
63 * the following conditions are aheared to. The following conditions
64 * apply to all code found in this distribution, be it the RC4, RSA,
65 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
66 * included with this distribution is covered by the same copyright terms
67 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
68 *
69 * Copyright remains Eric Young's, and as such any Copyright notices in
70 * the code are not to be removed.
71 * If this package is used in a product, Eric Young should be given attribution
72 * as the author of the parts of the library used.
73 * This can be in the form of a textual message at program startup or
74 * in documentation (online or textual) provided with the package.
75 *
76 * Redistribution and use in source and binary forms, with or without
77 * modification, are permitted provided that the following conditions
78 * are met:
79 * 1. Redistributions of source code must retain the copyright
80 * notice, this list of conditions and the following disclaimer.
81 * 2. Redistributions in binary form must reproduce the above copyright
82 * notice, this list of conditions and the following disclaimer in the
83 * documentation and/or other materials provided with the distribution.
84 * 3. All advertising materials mentioning features or use of this software
85 * must display the following acknowledgement:
86 * "This product includes cryptographic software written by
87 * Eric Young (eay@cryptsoft.com)"
88 * The word 'cryptographic' can be left out if the rouines from the library
89 * being used are not cryptographic related :-).
90 * 4. If you include any Windows specific code (or a derivative thereof) from
91 * the apps directory (application code) you must include an acknowledgement:
92 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
93 *
94 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
95 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
96 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
97 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
98 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
99 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
100 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
101 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
102 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
103 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
104 * SUCH DAMAGE.
105 *
106 * The licence and distribution terms for any publically available version or
107 * derivative of this code cannot be changed. i.e. this code cannot simply be
108 * copied and put under another distribution licence
109 * [including the GNU Public Licence.]
110 */
111
112 #include <pthread.h>
113 #include <stdio.h>
114
115 #include <openssl/opensslconf.h>
116
117 #include <openssl/err.h>
118 #include <openssl/rsa.h>
119
120 #include "bn_local.h"
121 #include "rsa_local.h"
122
123 #define BN_BLINDING_COUNTER 32
124
125 struct bn_blinding_st {
126 BIGNUM *A;
127 BIGNUM *Ai;
128 BIGNUM *e;
129 BIGNUM *mod;
130 pthread_t tid;
131 int counter;
132 BN_MONT_CTX *m_ctx;
133 int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
134 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
135 };
136
137 BN_BLINDING *
BN_BLINDING_new(const BIGNUM * e,const BIGNUM * mod,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)138 BN_BLINDING_new(const BIGNUM *e, const BIGNUM *mod, BN_CTX *ctx,
139 int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
140 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx), BN_MONT_CTX *m_ctx)
141 {
142 BN_BLINDING *ret = NULL;
143
144 if ((ret = calloc(1, sizeof(BN_BLINDING))) == NULL) {
145 BNerror(ERR_R_MALLOC_FAILURE);
146 goto err;
147 }
148 if ((ret->A = BN_new()) == NULL)
149 goto err;
150 if ((ret->Ai = BN_new()) == NULL)
151 goto err;
152 if ((ret->e = BN_dup(e)) == NULL)
153 goto err;
154 if ((ret->mod = BN_dup(mod)) == NULL)
155 goto err;
156 if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
157 BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
158
159 /* Update on first use. */
160 ret->counter = BN_BLINDING_COUNTER - 1;
161 ret->tid = pthread_self();
162
163 if (bn_mod_exp != NULL)
164 ret->bn_mod_exp = bn_mod_exp;
165 if (m_ctx != NULL)
166 ret->m_ctx = m_ctx;
167
168 return ret;
169
170 err:
171 BN_BLINDING_free(ret);
172
173 return NULL;
174 }
175
176 void
BN_BLINDING_free(BN_BLINDING * r)177 BN_BLINDING_free(BN_BLINDING *r)
178 {
179 if (r == NULL)
180 return;
181
182 BN_free(r->A);
183 BN_free(r->Ai);
184 BN_free(r->e);
185 BN_free(r->mod);
186 free(r);
187 }
188
189 static int
BN_BLINDING_setup(BN_BLINDING * b,BN_CTX * ctx)190 BN_BLINDING_setup(BN_BLINDING *b, BN_CTX *ctx)
191 {
192 if (!bn_rand_interval(b->A, 1, b->mod))
193 return 0;
194 if (BN_mod_inverse_ct(b->Ai, b->A, b->mod, ctx) == NULL)
195 return 0;
196
197 if (b->bn_mod_exp != NULL && b->m_ctx != NULL) {
198 if (!b->bn_mod_exp(b->A, b->A, b->e, b->mod, ctx, b->m_ctx))
199 return 0;
200 } else {
201 if (!BN_mod_exp_ct(b->A, b->A, b->e, b->mod, ctx))
202 return 0;
203 }
204
205 return 1;
206 }
207
208 static int
BN_BLINDING_update(BN_BLINDING * b,BN_CTX * ctx)209 BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
210 {
211 int ret = 0;
212
213 if (++b->counter >= BN_BLINDING_COUNTER) {
214 if (!BN_BLINDING_setup(b, ctx))
215 goto err;
216 b->counter = 0;
217 } else {
218 if (!BN_mod_sqr(b->A, b->A, b->mod, ctx))
219 goto err;
220 if (!BN_mod_sqr(b->Ai, b->Ai, b->mod, ctx))
221 goto err;
222 }
223
224 ret = 1;
225
226 err:
227 return ret;
228 }
229
230 int
BN_BLINDING_convert(BIGNUM * n,BIGNUM * inv,BN_BLINDING * b,BN_CTX * ctx)231 BN_BLINDING_convert(BIGNUM *n, BIGNUM *inv, BN_BLINDING *b, BN_CTX *ctx)
232 {
233 int ret = 0;
234
235 if (!BN_BLINDING_update(b, ctx))
236 goto err;
237
238 if (inv != NULL) {
239 if (!bn_copy(inv, b->Ai))
240 goto err;
241 }
242
243 ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
244
245 err:
246 return ret;
247 }
248
249 int
BN_BLINDING_invert(BIGNUM * n,const BIGNUM * inv,BN_BLINDING * b,BN_CTX * ctx)250 BN_BLINDING_invert(BIGNUM *n, const BIGNUM *inv, BN_BLINDING *b, BN_CTX *ctx)
251 {
252 if (inv == NULL)
253 inv = b->Ai;
254
255 return BN_mod_mul(n, n, inv, b->mod, ctx);
256 }
257
258 int
BN_BLINDING_is_local(BN_BLINDING * b)259 BN_BLINDING_is_local(BN_BLINDING *b)
260 {
261 return pthread_equal(pthread_self(), b->tid) != 0;
262 }
263
264 static BIGNUM *
rsa_get_public_exp(const BIGNUM * d,const BIGNUM * p,const BIGNUM * q,BN_CTX * ctx)265 rsa_get_public_exp(const BIGNUM *d, const BIGNUM *p, const BIGNUM *q,
266 BN_CTX *ctx)
267 {
268 BIGNUM *ret = NULL, *r0, *r1, *r2;
269
270 if (d == NULL || p == NULL || q == NULL)
271 return NULL;
272
273 BN_CTX_start(ctx);
274 if ((r0 = BN_CTX_get(ctx)) == NULL)
275 goto err;
276 if ((r1 = BN_CTX_get(ctx)) == NULL)
277 goto err;
278 if ((r2 = BN_CTX_get(ctx)) == NULL)
279 goto err;
280
281 if (!BN_sub(r1, p, BN_value_one()))
282 goto err;
283 if (!BN_sub(r2, q, BN_value_one()))
284 goto err;
285 if (!BN_mul(r0, r1, r2, ctx))
286 goto err;
287
288 ret = BN_mod_inverse_ct(NULL, d, r0, ctx);
289 err:
290 BN_CTX_end(ctx);
291 return ret;
292 }
293
294 BN_BLINDING *
RSA_setup_blinding(RSA * rsa,BN_CTX * in_ctx)295 RSA_setup_blinding(RSA *rsa, BN_CTX *in_ctx)
296 {
297 BIGNUM *e = NULL;
298 BIGNUM n;
299 BN_CTX *ctx = NULL;
300 BN_BLINDING *ret = NULL;
301
302 if ((ctx = in_ctx) == NULL)
303 ctx = BN_CTX_new();
304 if (ctx == NULL)
305 goto err;
306
307 BN_CTX_start(ctx);
308
309 if ((e = rsa->e) == NULL)
310 e = rsa_get_public_exp(rsa->d, rsa->p, rsa->q, ctx);
311 if (e == NULL) {
312 RSAerror(RSA_R_NO_PUBLIC_EXPONENT);
313 goto err;
314 }
315
316 BN_init(&n);
317 BN_with_flags(&n, rsa->n, BN_FLG_CONSTTIME);
318
319 if ((ret = BN_BLINDING_new(e, &n, ctx, rsa->meth->bn_mod_exp,
320 rsa->_method_mod_n)) == NULL) {
321 RSAerror(ERR_R_BN_LIB);
322 goto err;
323 }
324
325 err:
326 BN_CTX_end(ctx);
327 if (ctx != in_ctx)
328 BN_CTX_free(ctx);
329 if (e != rsa->e)
330 BN_free(e);
331
332 return ret;
333 }
334
335 void
RSA_blinding_off(RSA * rsa)336 RSA_blinding_off(RSA *rsa)
337 {
338 BN_BLINDING_free(rsa->blinding);
339 rsa->blinding = NULL;
340 rsa->flags |= RSA_FLAG_NO_BLINDING;
341 }
342 LCRYPTO_ALIAS(RSA_blinding_off);
343
344 int
RSA_blinding_on(RSA * rsa,BN_CTX * ctx)345 RSA_blinding_on(RSA *rsa, BN_CTX *ctx)
346 {
347 int ret = 0;
348
349 if (rsa->blinding != NULL)
350 RSA_blinding_off(rsa);
351
352 rsa->blinding = RSA_setup_blinding(rsa, ctx);
353 if (rsa->blinding == NULL)
354 goto err;
355
356 rsa->flags &= ~RSA_FLAG_NO_BLINDING;
357 ret = 1;
358 err:
359 return (ret);
360 }
361 LCRYPTO_ALIAS(RSA_blinding_on);
362