1 /* crypto/rsa/rsa_pk1.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
59 #include "constant_time_locl.h"
63 #include <openssl/bn.h>
64 #include <openssl/rsa.h>
65 #include <openssl/rand.h>
67 int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
68 const unsigned char *from, int flen)
73 if (flen > (tlen - RSA_PKCS1_PADDING_SIZE)) {
74 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_1,
75 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
79 p = (unsigned char *)to;
82 *(p++) = 1; /* Private Key BT (Block Type) */
84 /* pad out with 0xff data */
89 memcpy(p, from, (unsigned int)flen);
93 int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
94 const unsigned char *from, int flen,
98 const unsigned char *p;
101 if ((num != (flen + 1)) || (*(p++) != 01)) {
102 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
103 RSA_R_BLOCK_TYPE_IS_NOT_01);
107 /* scan over padding data */
108 j = flen - 1; /* one for type. */
109 for (i = 0; i < j; i++) {
110 if (*p != 0xff) { /* should decrypt to 0xff */
115 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
116 RSA_R_BAD_FIXED_HEADER_DECRYPT);
124 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
125 RSA_R_NULL_BEFORE_BLOCK_MISSING);
130 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
131 RSA_R_BAD_PAD_BYTE_COUNT);
134 i++; /* Skip over the '\0' */
137 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, RSA_R_DATA_TOO_LARGE);
140 memcpy(to, p, (unsigned int)j);
145 int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
146 const unsigned char *from, int flen)
151 if (flen > (tlen - 11)) {
152 RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2,
153 RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
157 p = (unsigned char *)to;
160 *(p++) = 2; /* Public Key BT (Block Type) */
162 /* pad out with non-zero random data */
165 if (RAND_bytes(p, j) <= 0)
167 for (i = 0; i < j; i++) {
170 if (RAND_bytes(p, 1) <= 0)
172 } while (*p == '\0');
178 memcpy(p, from, (unsigned int)flen);
182 int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
183 const unsigned char *from, int flen,
187 /* |em| is the encoded message, zero-padded to exactly |num| bytes */
188 unsigned char *em = NULL;
189 unsigned int good, found_zero_byte;
190 int zero_index = 0, msg_index, mlen = -1;
192 if (tlen < 0 || flen < 0)
196 * PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography Standard",
206 em = OPENSSL_malloc(num);
208 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
213 * Always do this zero-padding copy (even when num == flen) to avoid
214 * leaking that information. The copy still leaks some side-channel
215 * information, but it's impossible to have a fixed memory access
216 * pattern since we can't read out of the bounds of |from|.
218 * TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
220 memcpy(em + num - flen, from, flen);
222 good = constant_time_is_zero(em[0]);
223 good &= constant_time_eq(em[1], 2);
226 for (i = 2; i < num; i++) {
227 unsigned int equals0 = constant_time_is_zero(em[i]);
229 constant_time_select_int(~found_zero_byte & equals0, i,
231 found_zero_byte |= equals0;
235 * PS must be at least 8 bytes long, and it starts two bytes into |em|.
236 * If we never found a 0-byte, then |zero_index| is 0 and the check
239 good &= constant_time_ge((unsigned int)(zero_index), 2 + 8);
242 * Skip the zero byte. This is incorrect if we never found a zero-byte
243 * but in this case we also do not copy the message out.
245 msg_index = zero_index + 1;
246 mlen = num - msg_index;
249 * For good measure, do this check in constant time as well; it could
250 * leak something if |tlen| was assuming valid padding.
252 good &= constant_time_ge((unsigned int)(tlen), (unsigned int)(mlen));
255 * We can't continue in constant-time because we need to copy the result
256 * and we cannot fake its length. This unavoidably leaks timing
257 * information at the API boundary.
264 memcpy(to, em + msg_index, mlen);
268 OPENSSL_cleanse(em, num);
272 RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2,
273 RSA_R_PKCS_DECODING_ERROR);