bn_blind.c revision 280304 
1/* crypto/bn/bn_blind.c */
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 <stdio.h>
113#include "cryptlib.h"
114#include "bn_lcl.h"
115
116#define BN_BLINDING_COUNTER     32
117
118struct bn_blinding_st {
119    BIGNUM *A;
120    BIGNUM *Ai;
121    BIGNUM *e;
122    BIGNUM *mod;                /* just a reference */
123#ifndef OPENSSL_NO_DEPRECATED
124    unsigned long thread_id;    /* added in OpenSSL 0.9.6j and 0.9.7b; used
125                                 * only by crypto/rsa/rsa_eay.c, rsa_lib.c */
126#endif
127    CRYPTO_THREADID tid;
128    int counter;
129    unsigned long flags;
130    BN_MONT_CTX *m_ctx;
131    int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
132                       const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
133};
134
135BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
136{
137    BN_BLINDING *ret = NULL;
138
139    bn_check_top(mod);
140
141    if ((ret = (BN_BLINDING *)OPENSSL_malloc(sizeof(BN_BLINDING))) == NULL) {
142        BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
143        return (NULL);
144    }
145    memset(ret, 0, sizeof(BN_BLINDING));
146    if (A != NULL) {
147        if ((ret->A = BN_dup(A)) == NULL)
148            goto err;
149    }
150    if (Ai != NULL) {
151        if ((ret->Ai = BN_dup(Ai)) == NULL)
152            goto err;
153    }
154
155    /* save a copy of mod in the BN_BLINDING structure */
156    if ((ret->mod = BN_dup(mod)) == NULL)
157        goto err;
158    if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
159        BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
160
161    /*
162     * Set the counter to the special value -1 to indicate that this is
163     * never-used fresh blinding that does not need updating before first
164     * use.
165     */
166    ret->counter = -1;
167    CRYPTO_THREADID_current(&ret->tid);
168    return (ret);
169 err:
170    if (ret != NULL)
171        BN_BLINDING_free(ret);
172    return (NULL);
173}
174
175void BN_BLINDING_free(BN_BLINDING *r)
176{
177    if (r == NULL)
178        return;
179
180    if (r->A != NULL)
181        BN_free(r->A);
182    if (r->Ai != NULL)
183        BN_free(r->Ai);
184    if (r->e != NULL)
185        BN_free(r->e);
186    if (r->mod != NULL)
187        BN_free(r->mod);
188    OPENSSL_free(r);
189}
190
191int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
192{
193    int ret = 0;
194
195    if ((b->A == NULL) || (b->Ai == NULL)) {
196        BNerr(BN_F_BN_BLINDING_UPDATE, BN_R_NOT_INITIALIZED);
197        goto err;
198    }
199
200    if (b->counter == -1)
201        b->counter = 0;
202
203    if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
204        !(b->flags & BN_BLINDING_NO_RECREATE)) {
205        /* re-create blinding parameters */
206        if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
207            goto err;
208    } else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
209        if (!BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
210            goto err;
211        if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx))
212            goto err;
213    }
214
215    ret = 1;
216 err:
217    if (b->counter == BN_BLINDING_COUNTER)
218        b->counter = 0;
219    return (ret);
220}
221
222int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
223{
224    return BN_BLINDING_convert_ex(n, NULL, b, ctx);
225}
226
227int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
228{
229    int ret = 1;
230
231    bn_check_top(n);
232
233    if ((b->A == NULL) || (b->Ai == NULL)) {
234        BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED);
235        return (0);
236    }
237
238    if (b->counter == -1)
239        /* Fresh blinding, doesn't need updating. */
240        b->counter = 0;
241    else if (!BN_BLINDING_update(b, ctx))
242        return (0);
243
244    if (r != NULL) {
245        if (!BN_copy(r, b->Ai))
246            ret = 0;
247    }
248
249    if (!BN_mod_mul(n, n, b->A, b->mod, ctx))
250        ret = 0;
251
252    return ret;
253}
254
255int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
256{
257    return BN_BLINDING_invert_ex(n, NULL, b, ctx);
258}
259
260int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
261                          BN_CTX *ctx)
262{
263    int ret;
264
265    bn_check_top(n);
266
267    if (r != NULL)
268        ret = BN_mod_mul(n, n, r, b->mod, ctx);
269    else {
270        if (b->Ai == NULL) {
271            BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
272            return (0);
273        }
274        ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
275    }
276
277    bn_check_top(n);
278    return (ret);
279}
280
281#ifndef OPENSSL_NO_DEPRECATED
282unsigned long BN_BLINDING_get_thread_id(const BN_BLINDING *b)
283{
284    return b->thread_id;
285}
286
287void BN_BLINDING_set_thread_id(BN_BLINDING *b, unsigned long n)
288{
289    b->thread_id = n;
290}
291#endif
292
293CRYPTO_THREADID *BN_BLINDING_thread_id(BN_BLINDING *b)
294{
295    return &b->tid;
296}
297
298unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
299{
300    return b->flags;
301}
302
303void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
304{
305    b->flags = flags;
306}
307
308BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
309                                      const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
310                                      int (*bn_mod_exp) (BIGNUM *r,
311                                                         const BIGNUM *a,
312                                                         const BIGNUM *p,
313                                                         const BIGNUM *m,
314                                                         BN_CTX *ctx,
315                                                         BN_MONT_CTX *m_ctx),
316                                      BN_MONT_CTX *m_ctx)
317{
318    int retry_counter = 32;
319    BN_BLINDING *ret = NULL;
320
321    if (b == NULL)
322        ret = BN_BLINDING_new(NULL, NULL, m);
323    else
324        ret = b;
325
326    if (ret == NULL)
327        goto err;
328
329    if (ret->A == NULL && (ret->A = BN_new()) == NULL)
330        goto err;
331    if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
332        goto err;
333
334    if (e != NULL) {
335        if (ret->e != NULL)
336            BN_free(ret->e);
337        ret->e = BN_dup(e);
338    }
339    if (ret->e == NULL)
340        goto err;
341
342    if (bn_mod_exp != NULL)
343        ret->bn_mod_exp = bn_mod_exp;
344    if (m_ctx != NULL)
345        ret->m_ctx = m_ctx;
346
347    do {
348        if (!BN_rand_range(ret->A, ret->mod))
349            goto err;
350        if (BN_mod_inverse(ret->Ai, ret->A, ret->mod, ctx) == NULL) {
351            /*
352             * this should almost never happen for good RSA keys
353             */
354            unsigned long error = ERR_peek_last_error();
355            if (ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
356                if (retry_counter-- == 0) {
357                    BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
358                          BN_R_TOO_MANY_ITERATIONS);
359                    goto err;
360                }
361                ERR_clear_error();
362            } else
363                goto err;
364        } else
365            break;
366    } while (1);
367
368    if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
369        if (!ret->bn_mod_exp
370            (ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
371            goto err;
372    } else {
373        if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
374            goto err;
375    }
376
377    return ret;
378 err:
379    if (b == NULL && ret != NULL) {
380        BN_BLINDING_free(ret);
381        ret = NULL;
382    }
383
384    return ret;
385}
386