bn_blind.c revision 340704 
1/* crypto/bn/bn_blind.c */
2/* ====================================================================
3 * Copyright (c) 1998-2018 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 (b->m_ctx != NULL) {
210            if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
211                || !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
212                goto err;
213        } else {
214            if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
215                || !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
216                goto err;
217        }
218    }
219
220    ret = 1;
221 err:
222    if (b->counter == BN_BLINDING_COUNTER)
223        b->counter = 0;
224    return (ret);
225}
226
227int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
228{
229    return BN_BLINDING_convert_ex(n, NULL, b, ctx);
230}
231
232int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
233{
234    int ret = 1;
235
236    bn_check_top(n);
237
238    if ((b->A == NULL) || (b->Ai == NULL)) {
239        BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED);
240        return (0);
241    }
242
243    if (b->counter == -1)
244        /* Fresh blinding, doesn't need updating. */
245        b->counter = 0;
246    else if (!BN_BLINDING_update(b, ctx))
247        return (0);
248
249    if (r != NULL && (BN_copy(r, b->Ai) == NULL))
250        return 0;
251
252    if (b->m_ctx != NULL)
253        ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
254    else
255        ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
256
257    return ret;
258}
259
260int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
261{
262    return BN_BLINDING_invert_ex(n, NULL, b, ctx);
263}
264
265int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
266                          BN_CTX *ctx)
267{
268    int ret;
269
270    bn_check_top(n);
271
272    if (r == NULL && (r = b->Ai) == NULL) {
273        BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
274        return 0;
275    }
276
277    if (b->m_ctx != NULL) {
278        /* ensure that BN_mod_mul_montgomery takes pre-defined path */
279        if (n->dmax >= r->top) {
280            size_t i, rtop = r->top, ntop = n->top;
281            BN_ULONG mask;
282
283            for (i = 0; i < rtop; i++) {
284                mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
285                n->d[i] &= mask;
286            }
287            mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
288            /* always true, if (rtop >= ntop) n->top = r->top; */
289            n->top = (int)(rtop & ~mask) | (ntop & mask);
290            n->flags |= (BN_FLG_FIXED_TOP & ~mask);
291        }
292        ret = BN_mod_mul_montgomery(n, n, r, b->m_ctx, ctx);
293    } else {
294        ret = BN_mod_mul(n, n, r, b->mod, ctx);
295    }
296
297    bn_check_top(n);
298    return (ret);
299}
300
301#ifndef OPENSSL_NO_DEPRECATED
302unsigned long BN_BLINDING_get_thread_id(const BN_BLINDING *b)
303{
304    return b->thread_id;
305}
306
307void BN_BLINDING_set_thread_id(BN_BLINDING *b, unsigned long n)
308{
309    b->thread_id = n;
310}
311#endif
312
313CRYPTO_THREADID *BN_BLINDING_thread_id(BN_BLINDING *b)
314{
315    return &b->tid;
316}
317
318unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
319{
320    return b->flags;
321}
322
323void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
324{
325    b->flags = flags;
326}
327
328BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
329                                      const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
330                                      int (*bn_mod_exp) (BIGNUM *r,
331                                                         const BIGNUM *a,
332                                                         const BIGNUM *p,
333                                                         const BIGNUM *m,
334                                                         BN_CTX *ctx,
335                                                         BN_MONT_CTX *m_ctx),
336                                      BN_MONT_CTX *m_ctx)
337{
338    int retry_counter = 32;
339    BN_BLINDING *ret = NULL;
340
341    if (b == NULL)
342        ret = BN_BLINDING_new(NULL, NULL, m);
343    else
344        ret = b;
345
346    if (ret == NULL)
347        goto err;
348
349    if (ret->A == NULL && (ret->A = BN_new()) == NULL)
350        goto err;
351    if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
352        goto err;
353
354    if (e != NULL) {
355        if (ret->e != NULL)
356            BN_free(ret->e);
357        ret->e = BN_dup(e);
358    }
359    if (ret->e == NULL)
360        goto err;
361
362    if (bn_mod_exp != NULL)
363        ret->bn_mod_exp = bn_mod_exp;
364    if (m_ctx != NULL)
365        ret->m_ctx = m_ctx;
366
367    do {
368        if (!BN_rand_range(ret->A, ret->mod))
369            goto err;
370        if (BN_mod_inverse(ret->Ai, ret->A, ret->mod, ctx) == NULL) {
371            /*
372             * this should almost never happen for good RSA keys
373             */
374            unsigned long error = ERR_peek_last_error();
375            if (ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
376                if (retry_counter-- == 0) {
377                    BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
378                          BN_R_TOO_MANY_ITERATIONS);
379                    goto err;
380                }
381                ERR_clear_error();
382            } else
383                goto err;
384        } else
385            break;
386    } while (1);
387
388    if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
389        if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
390            goto err;
391    } else {
392        if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
393            goto err;
394    }
395
396    if (ret->m_ctx != NULL) {
397        if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
398            || !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
399            goto err;
400    }
401
402    return ret;
403 err:
404    if (b == NULL && ret != NULL) {
405        BN_BLINDING_free(ret);
406        ret = NULL;
407    }
408
409    return ret;
410}
411