Line data Source code
1 : /* crypto/rsa/rsa_pk1.c */
2 : /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 : * All rights reserved.
4 : *
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.
8 : *
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).
15 : *
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.
22 : *
23 : * Redistribution and use in source and binary forms, with or without
24 : * modification, are permitted provided that the following conditions
25 : * are met:
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)"
40 : *
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
51 : * SUCH DAMAGE.
52 : *
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.]
57 : */
58 :
59 : #include "constant_time_locl.h"
60 :
61 : #include <stdio.h>
62 : #include "cryptlib.h"
63 : #include <openssl/bn.h>
64 : #include <openssl/rsa.h>
65 : #include <openssl/rand.h>
66 :
67 381 : int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
68 : const unsigned char *from, int flen)
69 : {
70 : int j;
71 : unsigned char *p;
72 :
73 381 : if (flen > (tlen - RSA_PKCS1_PADDING_SIZE)) {
74 0 : RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_1,
75 : RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
76 0 : return (0);
77 : }
78 :
79 : p = (unsigned char *)to;
80 :
81 381 : *(p++) = 0;
82 381 : *(p++) = 1; /* Private Key BT (Block Type) */
83 :
84 : /* pad out with 0xff data */
85 381 : j = tlen - 3 - flen;
86 381 : memset(p, 0xff, j);
87 381 : p += j;
88 381 : *(p++) = '\0';
89 381 : memcpy(p, from, (unsigned int)flen);
90 381 : return (1);
91 : }
92 :
93 746 : int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
94 : const unsigned char *from, int flen,
95 : int num)
96 : {
97 : int i, j;
98 : const unsigned char *p;
99 :
100 : p = from;
101 746 : if ((num != (flen + 1)) || (*(p++) != 01)) {
102 1 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
103 : RSA_R_BLOCK_TYPE_IS_NOT_01);
104 1 : return (-1);
105 : }
106 :
107 : /* scan over padding data */
108 745 : j = flen - 1; /* one for type. */
109 49955 : for (i = 0; i < j; i++) {
110 49955 : if (*p != 0xff) { /* should decrypt to 0xff */
111 745 : if (*p == 0) {
112 745 : p++;
113 745 : break;
114 : } else {
115 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
116 : RSA_R_BAD_FIXED_HEADER_DECRYPT);
117 0 : return (-1);
118 : }
119 : }
120 49210 : p++;
121 : }
122 :
123 745 : if (i == j) {
124 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
125 : RSA_R_NULL_BEFORE_BLOCK_MISSING);
126 0 : return (-1);
127 : }
128 :
129 745 : if (i < 8) {
130 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1,
131 : RSA_R_BAD_PAD_BYTE_COUNT);
132 0 : return (-1);
133 : }
134 745 : i++; /* Skip over the '\0' */
135 745 : j -= i;
136 745 : if (j > tlen) {
137 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, RSA_R_DATA_TOO_LARGE);
138 0 : return (-1);
139 : }
140 745 : memcpy(to, p, (unsigned int)j);
141 :
142 745 : return (j);
143 : }
144 :
145 0 : int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
146 : const unsigned char *from, int flen)
147 : {
148 : int i, j;
149 : unsigned char *p;
150 :
151 0 : if (flen > (tlen - 11)) {
152 0 : RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2,
153 : RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
154 0 : return (0);
155 : }
156 :
157 : p = (unsigned char *)to;
158 :
159 0 : *(p++) = 0;
160 0 : *(p++) = 2; /* Public Key BT (Block Type) */
161 :
162 : /* pad out with non-zero random data */
163 0 : j = tlen - 3 - flen;
164 :
165 0 : if (RAND_bytes(p, j) <= 0)
166 : return (0);
167 0 : for (i = 0; i < j; i++) {
168 0 : if (*p == '\0')
169 : do {
170 0 : if (RAND_bytes(p, 1) <= 0)
171 : return (0);
172 0 : } while (*p == '\0');
173 0 : p++;
174 : }
175 :
176 0 : *(p++) = '\0';
177 :
178 0 : memcpy(p, from, (unsigned int)flen);
179 0 : return (1);
180 : }
181 :
182 0 : int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
183 : const unsigned char *from, int flen,
184 : int num)
185 : {
186 : int i;
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;
191 :
192 0 : if (tlen < 0 || flen < 0)
193 : return -1;
194 :
195 : /*
196 : * PKCS#1 v1.5 decryption. See "PKCS #1 v2.2: RSA Cryptography Standard",
197 : * section 7.2.2.
198 : */
199 :
200 0 : if (flen > num)
201 : goto err;
202 :
203 0 : if (num < 11)
204 : goto err;
205 :
206 0 : em = OPENSSL_malloc(num);
207 0 : if (em == NULL) {
208 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE);
209 0 : return -1;
210 : }
211 0 : memset(em, 0, num);
212 : /*
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|.
217 : *
218 : * TODO(emilia): Consider porting BN_bn2bin_padded from BoringSSL.
219 : */
220 0 : memcpy(em + num - flen, from, flen);
221 :
222 0 : good = constant_time_is_zero(em[0]);
223 0 : good &= constant_time_eq(em[1], 2);
224 :
225 : found_zero_byte = 0;
226 0 : for (i = 2; i < num; i++) {
227 0 : unsigned int equals0 = constant_time_is_zero(em[i]);
228 : zero_index =
229 0 : constant_time_select_int(~found_zero_byte & equals0, i,
230 : zero_index);
231 0 : found_zero_byte |= equals0;
232 : }
233 :
234 : /*
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
237 : * also fails.
238 : */
239 0 : good &= constant_time_ge((unsigned int)(zero_index), 2 + 8);
240 :
241 : /*
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.
244 : */
245 0 : msg_index = zero_index + 1;
246 0 : mlen = num - msg_index;
247 :
248 : /*
249 : * For good measure, do this check in constant time as well; it could
250 : * leak something if |tlen| was assuming valid padding.
251 : */
252 0 : good &= constant_time_ge((unsigned int)(tlen), (unsigned int)(mlen));
253 :
254 : /*
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.
258 : * TODO(emilia): this could be addressed at the call site,
259 : * see BoringSSL commit 0aa0767340baf925bda4804882aab0cb974b2d26.
260 : */
261 0 : if (!good) {
262 : mlen = -1;
263 : goto err;
264 : }
265 :
266 0 : memcpy(to, em + msg_index, mlen);
267 :
268 : err:
269 0 : if (em != NULL)
270 0 : OPENSSL_free(em);
271 0 : if (mlen == -1)
272 0 : RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2,
273 : RSA_R_PKCS_DECODING_ERROR);
274 0 : return mlen;
275 : }
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