1 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
2 * project 2005.
3 */
4 /* ====================================================================
5 * Copyright (c) 2005 The OpenSSL Project. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 *
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the
17 * distribution.
18 *
19 * 3. All advertising materials mentioning features or use of this
20 * software must display the following acknowledgment:
21 * "This product includes software developed by the OpenSSL Project
22 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
23 *
24 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
25 * endorse or promote products derived from this software without
26 * prior written permission. For written permission, please contact
27 * licensing@OpenSSL.org.
28 *
29 * 5. Products derived from this software may not be called "OpenSSL"
30 * nor may "OpenSSL" appear in their names without prior written
31 * permission of the OpenSSL Project.
32 *
33 * 6. Redistributions of any form whatsoever must retain the following
34 * acknowledgment:
35 * "This product includes software developed by the OpenSSL Project
36 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
37 *
38 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
39 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
40 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
41 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
42 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
43 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
44 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
45 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
46 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
47 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
48 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
49 * OF THE POSSIBILITY OF SUCH DAMAGE.
50 * ====================================================================
51 *
52 * This product includes cryptographic software written by Eric Young
53 * (eay@cryptsoft.com). This product includes software written by Tim
54 * Hudson (tjh@cryptsoft.com). */
55
56 #include "../../internal.h"
57
58 #include <ring-core/mem.h>
59
RSA_padding_check_oaep(size_t * out_len,uint8_t y,const uint8_t db[],size_t dblen,const uint8_t phash[],size_t mdlen)60 int RSA_padding_check_oaep(size_t *out_len, uint8_t y, const uint8_t db[],
61 size_t dblen, const uint8_t phash[],
62 size_t mdlen) {
63 crypto_word bad = ~constant_time_is_zero_w(OPENSSL_memcmp(db, phash, mdlen));
64 bad |= ~constant_time_is_zero_w(y);
65
66 crypto_word looking_for_one_byte = CONSTTIME_TRUE_W;
67 size_t one_index = 0;
68 for (size_t i = mdlen; i < dblen; i++) {
69 crypto_word equals1 = constant_time_eq_w(db[i], 1);
70 crypto_word equals0 = constant_time_eq_w(db[i], 0);
71 one_index =
72 constant_time_select_w(looking_for_one_byte & equals1, i, one_index);
73 looking_for_one_byte =
74 constant_time_select_w(equals1, 0, looking_for_one_byte);
75 bad |= looking_for_one_byte & ~equals0;
76 }
77
78 bad |= looking_for_one_byte;
79
80 if (bad) {
81 goto decoding_err;
82 }
83
84 one_index++;
85 size_t mlen = dblen - one_index;
86
87 *out_len = mlen;
88
89 return 1;
90
91 decoding_err:
92 return 0;
93 }
94