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 |
38 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR |
39 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
40 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
41 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
42 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
43 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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. |
61 | static const uint8_t kDefaultIV[] = { |
62 | 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, |
63 | }; |
64 | |
65 | static const unsigned kBound = 6; |
66 | |
67 | int 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 |
106 | static 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 | |
140 | int 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 |
159 | static const uint8_t kPaddingConstant[4] = {0xa6, 0x59, 0x59, 0xa6}; |
160 | |
161 | int 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 | |
202 | int 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 | |