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58964a49 RE |
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. | |
0f113f3e | 8 | * |
58964a49 RE |
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). | |
0f113f3e | 15 | * |
58964a49 RE |
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. | |
0f113f3e | 22 | * |
58964a49 RE |
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 :-). | |
0f113f3e | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
58964a49 RE |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
0f113f3e | 40 | * |
58964a49 RE |
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. | |
0f113f3e | 52 | * |
58964a49 RE |
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 | ||
7f09a877 | 59 | #include "constant_time_locl.h" |
294d1e36 | 60 | |
58964a49 RE |
61 | #include <stdio.h> |
62 | #include "cryptlib.h" | |
ec577822 BM |
63 | #include <openssl/bn.h> |
64 | #include <openssl/rsa.h> | |
65 | #include <openssl/rand.h> | |
58964a49 | 66 | |
6b691a5c | 67 | int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen, |
0f113f3e MC |
68 | const unsigned char *from, int flen) |
69 | { | |
70 | int j; | |
71 | unsigned char *p; | |
72 | ||
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); | |
76 | return (0); | |
77 | } | |
78 | ||
79 | p = (unsigned char *)to; | |
80 | ||
81 | *(p++) = 0; | |
82 | *(p++) = 1; /* Private Key BT (Block Type) */ | |
83 | ||
84 | /* pad out with 0xff data */ | |
85 | j = tlen - 3 - flen; | |
86 | memset(p, 0xff, j); | |
87 | p += j; | |
88 | *(p++) = '\0'; | |
89 | memcpy(p, from, (unsigned int)flen); | |
90 | return (1); | |
91 | } | |
58964a49 | 92 | |
6b691a5c | 93 | int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen, |
0f113f3e MC |
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 | if ((num != (flen + 1)) || (*(p++) != 01)) { | |
102 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, | |
103 | RSA_R_BLOCK_TYPE_IS_NOT_01); | |
104 | return (-1); | |
105 | } | |
106 | ||
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 */ | |
111 | if (*p == 0) { | |
112 | p++; | |
113 | break; | |
114 | } else { | |
115 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, | |
116 | RSA_R_BAD_FIXED_HEADER_DECRYPT); | |
117 | return (-1); | |
118 | } | |
119 | } | |
120 | p++; | |
121 | } | |
122 | ||
123 | if (i == j) { | |
124 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, | |
125 | RSA_R_NULL_BEFORE_BLOCK_MISSING); | |
126 | return (-1); | |
127 | } | |
128 | ||
129 | if (i < 8) { | |
130 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, | |
131 | RSA_R_BAD_PAD_BYTE_COUNT); | |
132 | return (-1); | |
133 | } | |
134 | i++; /* Skip over the '\0' */ | |
135 | j -= i; | |
136 | if (j > tlen) { | |
137 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_1, RSA_R_DATA_TOO_LARGE); | |
138 | return (-1); | |
139 | } | |
140 | memcpy(to, p, (unsigned int)j); | |
141 | ||
142 | return (j); | |
143 | } | |
58964a49 | 144 | |
6b691a5c | 145 | int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen, |
0f113f3e MC |
146 | const unsigned char *from, int flen) |
147 | { | |
148 | int i, j; | |
149 | unsigned char *p; | |
150 | ||
151 | if (flen > (tlen - 11)) { | |
152 | RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_TYPE_2, | |
153 | RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE); | |
154 | return (0); | |
155 | } | |
156 | ||
157 | p = (unsigned char *)to; | |
158 | ||
159 | *(p++) = 0; | |
160 | *(p++) = 2; /* Public Key BT (Block Type) */ | |
161 | ||
162 | /* pad out with non-zero random data */ | |
163 | j = tlen - 3 - flen; | |
164 | ||
165 | if (RAND_bytes(p, j) <= 0) | |
166 | return (0); | |
167 | for (i = 0; i < j; i++) { | |
168 | if (*p == '\0') | |
169 | do { | |
170 | if (RAND_bytes(p, 1) <= 0) | |
171 | return (0); | |
172 | } while (*p == '\0'); | |
173 | p++; | |
174 | } | |
175 | ||
176 | *(p++) = '\0'; | |
177 | ||
178 | memcpy(p, from, (unsigned int)flen); | |
179 | return (1); | |
180 | } | |
58964a49 | 181 | |
6b691a5c | 182 | int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen, |
0f113f3e MC |
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 | 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 | if (flen > num) | |
201 | goto err; | |
202 | ||
203 | if (num < 11) | |
204 | goto err; | |
205 | ||
206 | em = OPENSSL_malloc(num); | |
207 | if (em == NULL) { | |
208 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, ERR_R_MALLOC_FAILURE); | |
209 | return -1; | |
210 | } | |
211 | 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 | memcpy(em + num - flen, from, flen); | |
221 | ||
222 | good = constant_time_is_zero(em[0]); | |
223 | good &= constant_time_eq(em[1], 2); | |
224 | ||
225 | found_zero_byte = 0; | |
226 | for (i = 2; i < num; i++) { | |
227 | unsigned int equals0 = constant_time_is_zero(em[i]); | |
228 | zero_index = | |
229 | constant_time_select_int(~found_zero_byte & equals0, i, | |
230 | zero_index); | |
231 | 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 | 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 | msg_index = zero_index + 1; | |
246 | 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 | 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 | if (!good) { | |
262 | mlen = -1; | |
263 | goto err; | |
264 | } | |
265 | ||
266 | memcpy(to, em + msg_index, mlen); | |
267 | ||
268 | err: | |
269 | if (em != NULL) | |
270 | OPENSSL_free(em); | |
271 | if (mlen == -1) | |
272 | RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_TYPE_2, | |
273 | RSA_R_PKCS_DECODING_ERROR); | |
274 | return mlen; | |
275 | } |