1/* ====================================================================
2 * Copyright (c) 2001-2011 The OpenSSL Project. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * 3. All advertising materials mentioning features or use of this
17 * software must display the following acknowledgment:
18 * "This product includes software developed by the OpenSSL Project
19 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
20 *
21 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
22 * endorse or promote products derived from this software without
23 * prior written permission. For written permission, please contact
24 * openssl-core@openssl.org.
25 *
26 * 5. Products derived from this software may not be called "OpenSSL"
27 * nor may "OpenSSL" appear in their names without prior written
28 * permission of the OpenSSL Project.
29 *
30 * 6. Redistributions of any form whatsoever must retain the following
31 * acknowledgment:
32 * "This product includes software developed by the OpenSSL Project
33 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
34 *
35 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
36 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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41 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
42 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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44 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
45 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
46 * OF THE POSSIBILITY OF SUCH DAMAGE.
47 * ==================================================================== */
48
49#include <openssl/aes.h>
50
51#include <assert.h>
52#include <limits.h>
53#include <string.h>
54
55#include <openssl/mem.h>
56
57#include "../../internal.h"
58
59
60// kDefaultIV is the default IV value given in RFC 3394, 2.2.3.1.
61static const uint8_t kDefaultIV[] = {
62 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
63};
64
65static const unsigned kBound = 6;
66
67int AES_wrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
68 const uint8_t *in, size_t in_len) {
69 // See RFC 3394, section 2.2.1. Additionally, note that section 2 requires the
70 // plaintext be at least two 8-byte blocks.
71
72 if (in_len > INT_MAX - 8 || in_len < 16 || in_len % 8 != 0) {
73 return -1;
74 }
75
76 if (iv == NULL) {
77 iv = kDefaultIV;
78 }
79
80 OPENSSL_memmove(out + 8, in, in_len);
81 uint8_t A[AES_BLOCK_SIZE];
82 OPENSSL_memcpy(A, iv, 8);
83
84 size_t n = in_len / 8;
85
86 for (unsigned j = 0; j < kBound; j++) {
87 for (size_t i = 1; i <= n; i++) {
88 OPENSSL_memcpy(A + 8, out + 8 * i, 8);
89 AES_encrypt(A, A, key);
90
91 uint32_t t = (uint32_t)(n * j + i);
92 A[7] ^= t & 0xff;
93 A[6] ^= (t >> 8) & 0xff;
94 A[5] ^= (t >> 16) & 0xff;
95 A[4] ^= (t >> 24) & 0xff;
96 OPENSSL_memcpy(out + 8 * i, A + 8, 8);
97 }
98 }
99
100 OPENSSL_memcpy(out, A, 8);
101 return (int)in_len + 8;
102}
103
104// aes_unwrap_key_inner performs steps one and two from
105// https://tools.ietf.org/html/rfc3394#section-2.2.2
106static int aes_unwrap_key_inner(const AES_KEY *key, uint8_t *out,
107 uint8_t out_iv[8], const uint8_t *in,
108 size_t in_len) {
109 // See RFC 3394, section 2.2.2. Additionally, note that section 2 requires the
110 // plaintext be at least two 8-byte blocks, so the ciphertext must be at least
111 // three blocks.
112
113 if (in_len > INT_MAX || in_len < 24 || in_len % 8 != 0) {
114 return 0;
115 }
116
117 uint8_t A[AES_BLOCK_SIZE];
118 OPENSSL_memcpy(A, in, 8);
119 OPENSSL_memmove(out, in + 8, in_len - 8);
120
121 size_t n = (in_len / 8) - 1;
122
123 for (unsigned j = kBound - 1; j < kBound; j--) {
124 for (size_t i = n; i > 0; i--) {
125 uint32_t t = (uint32_t)(n * j + i);
126 A[7] ^= t & 0xff;
127 A[6] ^= (t >> 8) & 0xff;
128 A[5] ^= (t >> 16) & 0xff;
129 A[4] ^= (t >> 24) & 0xff;
130 OPENSSL_memcpy(A + 8, out + 8 * (i - 1), 8);
131 AES_decrypt(A, A, key);
132 OPENSSL_memcpy(out + 8 * (i - 1), A + 8, 8);
133 }
134 }
135
136 memcpy(out_iv, A, 8);
137 return 1;
138}
139
140int AES_unwrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
141 const uint8_t *in, size_t in_len) {
142 uint8_t calculated_iv[8];
143 if (!aes_unwrap_key_inner(key, out, calculated_iv, in, in_len)) {
144 return -1;
145 }
146
147 if (iv == NULL) {
148 iv = kDefaultIV;
149 }
150 if (CRYPTO_memcmp(calculated_iv, iv, 8) != 0) {
151 return -1;
152 }
153
154 return (int)in_len - 8;
155}
156
157// kPaddingConstant is used in Key Wrap with Padding. See
158// https://tools.ietf.org/html/rfc5649#section-3
159static const uint8_t kPaddingConstant[4] = {0xa6, 0x59, 0x59, 0xa6};
160
161int AES_wrap_key_padded(const AES_KEY *key, uint8_t *out, size_t *out_len,
162 size_t max_out, const uint8_t *in, size_t in_len) {
163 // See https://tools.ietf.org/html/rfc5649#section-4.1
164 const uint32_t in_len32_be = CRYPTO_bswap4(in_len);
165 const uint64_t in_len64 = in_len;
166 const size_t padded_len = (in_len + 7) & ~7;
167
168 *out_len = 0;
169 if (in_len == 0 || in_len64 > 0xffffffffu || in_len + 7 < in_len ||
170 padded_len + 8 < padded_len || max_out < padded_len + 8) {
171 return 0;
172 }
173
174 uint8_t block[AES_BLOCK_SIZE];
175 memcpy(block, kPaddingConstant, sizeof(kPaddingConstant));
176 memcpy(block + 4, &in_len32_be, sizeof(in_len32_be));
177
178 if (in_len <= 8) {
179 memset(block + 8, 0, 8);
180 memcpy(block + 8, in, in_len);
181 AES_encrypt(block, out, key);
182 *out_len = AES_BLOCK_SIZE;
183 return 1;
184 }
185
186 uint8_t *padded_in = OPENSSL_malloc(padded_len);
187 if (padded_in == NULL) {
188 return 0;
189 }
190 assert(padded_len >= 8);
191 memset(padded_in + padded_len - 8, 0, 8);
192 memcpy(padded_in, in, in_len);
193 const int ret = AES_wrap_key(key, block, out, padded_in, padded_len);
194 OPENSSL_free(padded_in);
195 if (ret < 0) {
196 return 0;
197 }
198 *out_len = ret;
199 return 1;
200}
201
202int AES_unwrap_key_padded(const AES_KEY *key, uint8_t *out, size_t *out_len,
203 size_t max_out, const uint8_t *in, size_t in_len) {
204 *out_len = 0;
205 if (in_len < AES_BLOCK_SIZE || max_out < in_len - 8) {
206 return 0;
207 }
208
209 uint8_t iv[8];
210 if (in_len == AES_BLOCK_SIZE) {
211 uint8_t block[AES_BLOCK_SIZE];
212 AES_decrypt(in, block, key);
213 memcpy(iv, block, sizeof(iv));
214 memcpy(out, block + 8, 8);
215 } else if (!aes_unwrap_key_inner(key, out, iv, in, in_len)) {
216 return 0;
217 }
218 assert(in_len % 8 == 0);
219
220 crypto_word_t ok = constant_time_eq_int(
221 CRYPTO_memcmp(iv, kPaddingConstant, sizeof(kPaddingConstant)), 0);
222
223 uint32_t claimed_len32;
224 memcpy(&claimed_len32, iv + 4, sizeof(claimed_len32));
225 const size_t claimed_len = CRYPTO_bswap4(claimed_len32);
226 ok &= ~constant_time_is_zero_w(claimed_len);
227 ok &= constant_time_eq_w((claimed_len - 1) >> 3, (in_len - 9) >> 3);
228
229 // Check that padding bytes are all zero.
230 for (size_t i = in_len - 15; i < in_len - 8; i++) {
231 ok &= constant_time_is_zero_w(constant_time_ge_8(i, claimed_len) & out[i]);
232 }
233
234 *out_len = constant_time_select_w(ok, claimed_len, 0);
235 return ok & 1;
236}
237