1 | /* |
2 | * Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved. |
3 | * |
4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at |
7 | * https://www.openssl.org/source/license.html |
8 | */ |
9 | |
10 | /** Beware! |
11 | * |
12 | * Following wrapping modes were designed for AES but this implementation |
13 | * allows you to use them for any 128 bit block cipher. |
14 | */ |
15 | |
16 | #include "internal/cryptlib.h" |
17 | #include <openssl/modes.h> |
18 | |
19 | /** RFC 3394 section 2.2.3.1 Default Initial Value */ |
20 | static const unsigned char default_iv[] = { |
21 | 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, |
22 | }; |
23 | |
24 | /** RFC 5649 section 3 Alternative Initial Value 32-bit constant */ |
25 | static const unsigned char default_aiv[] = { |
26 | 0xA6, 0x59, 0x59, 0xA6 |
27 | }; |
28 | |
29 | /** Input size limit: lower than maximum of standards but far larger than |
30 | * anything that will be used in practice. |
31 | */ |
32 | #define CRYPTO128_WRAP_MAX (1UL << 31) |
33 | |
34 | /** Wrapping according to RFC 3394 section 2.2.1. |
35 | * |
36 | * @param[in] key Key value. |
37 | * @param[in] iv IV value. Length = 8 bytes. NULL = use default_iv. |
38 | * @param[in] in Plaintext as n 64-bit blocks, n >= 2. |
39 | * @param[in] inlen Length of in. |
40 | * @param[out] out Ciphertext. Minimal buffer length = (inlen + 8) bytes. |
41 | * Input and output buffers can overlap if block function |
42 | * supports that. |
43 | * @param[in] block Block processing function. |
44 | * @return 0 if inlen does not consist of n 64-bit blocks, n >= 2. |
45 | * or if inlen > CRYPTO128_WRAP_MAX. |
46 | * Output length if wrapping succeeded. |
47 | */ |
48 | size_t CRYPTO_128_wrap(void *key, const unsigned char *iv, |
49 | unsigned char *out, |
50 | const unsigned char *in, size_t inlen, |
51 | block128_f block) |
52 | { |
53 | unsigned char *A, B[16], *R; |
54 | size_t i, j, t; |
55 | if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX)) |
56 | return 0; |
57 | A = B; |
58 | t = 1; |
59 | memmove(out + 8, in, inlen); |
60 | if (!iv) |
61 | iv = default_iv; |
62 | |
63 | memcpy(A, iv, 8); |
64 | |
65 | for (j = 0; j < 6; j++) { |
66 | R = out + 8; |
67 | for (i = 0; i < inlen; i += 8, t++, R += 8) { |
68 | memcpy(B + 8, R, 8); |
69 | block(B, B, key); |
70 | A[7] ^= (unsigned char)(t & 0xff); |
71 | if (t > 0xff) { |
72 | A[6] ^= (unsigned char)((t >> 8) & 0xff); |
73 | A[5] ^= (unsigned char)((t >> 16) & 0xff); |
74 | A[4] ^= (unsigned char)((t >> 24) & 0xff); |
75 | } |
76 | memcpy(R, B + 8, 8); |
77 | } |
78 | } |
79 | memcpy(out, A, 8); |
80 | return inlen + 8; |
81 | } |
82 | |
83 | /** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2. |
84 | * The IV check (step 3) is responsibility of the caller. |
85 | * |
86 | * @param[in] key Key value. |
87 | * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes. |
88 | * @param[out] out Plaintext without IV. |
89 | * Minimal buffer length = (inlen - 8) bytes. |
90 | * Input and output buffers can overlap if block function |
91 | * supports that. |
92 | * @param[in] in Ciphertext as n 64-bit blocks. |
93 | * @param[in] inlen Length of in. |
94 | * @param[in] block Block processing function. |
95 | * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX] |
96 | * or if inlen is not a multiple of 8. |
97 | * Output length otherwise. |
98 | */ |
99 | static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv, |
100 | unsigned char *out, |
101 | const unsigned char *in, size_t inlen, |
102 | block128_f block) |
103 | { |
104 | unsigned char *A, B[16], *R; |
105 | size_t i, j, t; |
106 | inlen -= 8; |
107 | if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX)) |
108 | return 0; |
109 | A = B; |
110 | t = 6 * (inlen >> 3); |
111 | memcpy(A, in, 8); |
112 | memmove(out, in + 8, inlen); |
113 | for (j = 0; j < 6; j++) { |
114 | R = out + inlen - 8; |
115 | for (i = 0; i < inlen; i += 8, t--, R -= 8) { |
116 | A[7] ^= (unsigned char)(t & 0xff); |
117 | if (t > 0xff) { |
118 | A[6] ^= (unsigned char)((t >> 8) & 0xff); |
119 | A[5] ^= (unsigned char)((t >> 16) & 0xff); |
120 | A[4] ^= (unsigned char)((t >> 24) & 0xff); |
121 | } |
122 | memcpy(B + 8, R, 8); |
123 | block(B, B, key); |
124 | memcpy(R, B + 8, 8); |
125 | } |
126 | } |
127 | memcpy(iv, A, 8); |
128 | return inlen; |
129 | } |
130 | |
131 | /** Unwrapping according to RFC 3394 section 2.2.2, including the IV check. |
132 | * The first block of plaintext has to match the supplied IV, otherwise an |
133 | * error is returned. |
134 | * |
135 | * @param[in] key Key value. |
136 | * @param[out] iv IV value to match against. Length = 8 bytes. |
137 | * NULL = use default_iv. |
138 | * @param[out] out Plaintext without IV. |
139 | * Minimal buffer length = (inlen - 8) bytes. |
140 | * Input and output buffers can overlap if block function |
141 | * supports that. |
142 | * @param[in] in Ciphertext as n 64-bit blocks. |
143 | * @param[in] inlen Length of in. |
144 | * @param[in] block Block processing function. |
145 | * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX] |
146 | * or if inlen is not a multiple of 8 |
147 | * or if IV doesn't match expected value. |
148 | * Output length otherwise. |
149 | */ |
150 | size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv, |
151 | unsigned char *out, const unsigned char *in, |
152 | size_t inlen, block128_f block) |
153 | { |
154 | size_t ret; |
155 | unsigned char got_iv[8]; |
156 | |
157 | ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block); |
158 | if (ret == 0) |
159 | return 0; |
160 | |
161 | if (!iv) |
162 | iv = default_iv; |
163 | if (CRYPTO_memcmp(got_iv, iv, 8)) { |
164 | OPENSSL_cleanse(out, ret); |
165 | return 0; |
166 | } |
167 | return ret; |
168 | } |
169 | |
170 | /** Wrapping according to RFC 5649 section 4.1. |
171 | * |
172 | * @param[in] key Key value. |
173 | * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv. |
174 | * @param[out] out Ciphertext. Minimal buffer length = (inlen + 15) bytes. |
175 | * Input and output buffers can overlap if block function |
176 | * supports that. |
177 | * @param[in] in Plaintext as n 64-bit blocks, n >= 2. |
178 | * @param[in] inlen Length of in. |
179 | * @param[in] block Block processing function. |
180 | * @return 0 if inlen is out of range [1, CRYPTO128_WRAP_MAX]. |
181 | * Output length if wrapping succeeded. |
182 | */ |
183 | size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv, |
184 | unsigned char *out, |
185 | const unsigned char *in, size_t inlen, |
186 | block128_f block) |
187 | { |
188 | /* n: number of 64-bit blocks in the padded key data |
189 | * |
190 | * If length of plain text is not a multiple of 8, pad the plain text octet |
191 | * string on the right with octets of zeros, where final length is the |
192 | * smallest multiple of 8 that is greater than length of plain text. |
193 | * If length of plain text is a multiple of 8, then there is no padding. */ |
194 | const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */ |
195 | const size_t padded_len = blocks_padded * 8; |
196 | const size_t padding_len = padded_len - inlen; |
197 | /* RFC 5649 section 3: Alternative Initial Value */ |
198 | unsigned char aiv[8]; |
199 | int ret; |
200 | |
201 | /* Section 1: use 32-bit fixed field for plaintext octet length */ |
202 | if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX) |
203 | return 0; |
204 | |
205 | /* Section 3: Alternative Initial Value */ |
206 | if (!icv) |
207 | memcpy(aiv, default_aiv, 4); |
208 | else |
209 | memcpy(aiv, icv, 4); /* Standard doesn't mention this. */ |
210 | |
211 | aiv[4] = (inlen >> 24) & 0xFF; |
212 | aiv[5] = (inlen >> 16) & 0xFF; |
213 | aiv[6] = (inlen >> 8) & 0xFF; |
214 | aiv[7] = inlen & 0xFF; |
215 | |
216 | if (padded_len == 8) { |
217 | /* |
218 | * Section 4.1 - special case in step 2: If the padded plaintext |
219 | * contains exactly eight octets, then prepend the AIV and encrypt |
220 | * the resulting 128-bit block using AES in ECB mode. |
221 | */ |
222 | memmove(out + 8, in, inlen); |
223 | memcpy(out, aiv, 8); |
224 | memset(out + 8 + inlen, 0, padding_len); |
225 | block(out, out, key); |
226 | ret = 16; /* AIV + padded input */ |
227 | } else { |
228 | memmove(out, in, inlen); |
229 | memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */ |
230 | ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block); |
231 | } |
232 | |
233 | return ret; |
234 | } |
235 | |
236 | /** Unwrapping according to RFC 5649 section 4.2. |
237 | * |
238 | * @param[in] key Key value. |
239 | * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv. |
240 | * @param[out] out Plaintext. Minimal buffer length = (inlen - 8) bytes. |
241 | * Input and output buffers can overlap if block function |
242 | * supports that. |
243 | * @param[in] in Ciphertext as n 64-bit blocks. |
244 | * @param[in] inlen Length of in. |
245 | * @param[in] block Block processing function. |
246 | * @return 0 if inlen is out of range [16, CRYPTO128_WRAP_MAX], |
247 | * or if inlen is not a multiple of 8 |
248 | * or if IV and message length indicator doesn't match. |
249 | * Output length if unwrapping succeeded and IV matches. |
250 | */ |
251 | size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv, |
252 | unsigned char *out, |
253 | const unsigned char *in, size_t inlen, |
254 | block128_f block) |
255 | { |
256 | /* n: number of 64-bit blocks in the padded key data */ |
257 | size_t n = inlen / 8 - 1; |
258 | size_t padded_len; |
259 | size_t padding_len; |
260 | size_t ptext_len; |
261 | /* RFC 5649 section 3: Alternative Initial Value */ |
262 | unsigned char aiv[8]; |
263 | static unsigned char zeros[8] = { 0x0 }; |
264 | size_t ret; |
265 | |
266 | /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */ |
267 | if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX) |
268 | return 0; |
269 | |
270 | if (inlen == 16) { |
271 | /* |
272 | * Section 4.2 - special case in step 1: When n=1, the ciphertext |
273 | * contains exactly two 64-bit blocks and they are decrypted as a |
274 | * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] | |
275 | * C[1]) |
276 | */ |
277 | unsigned char buff[16]; |
278 | |
279 | block(in, buff, key); |
280 | memcpy(aiv, buff, 8); |
281 | /* Remove AIV */ |
282 | memcpy(out, buff + 8, 8); |
283 | padded_len = 8; |
284 | OPENSSL_cleanse(buff, inlen); |
285 | } else { |
286 | padded_len = inlen - 8; |
287 | ret = crypto_128_unwrap_raw(key, aiv, out, in, inlen, block); |
288 | if (padded_len != ret) { |
289 | OPENSSL_cleanse(out, inlen); |
290 | return 0; |
291 | } |
292 | } |
293 | |
294 | /* |
295 | * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a |
296 | * user-supplied value can be used (even if standard doesn't mention |
297 | * this). |
298 | */ |
299 | if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4)) |
300 | || (icv && CRYPTO_memcmp(aiv, icv, 4))) { |
301 | OPENSSL_cleanse(out, inlen); |
302 | return 0; |
303 | } |
304 | |
305 | /* |
306 | * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len = |
307 | * LSB(32,AIV). |
308 | */ |
309 | |
310 | ptext_len = ((unsigned int)aiv[4] << 24) |
311 | | ((unsigned int)aiv[5] << 16) |
312 | | ((unsigned int)aiv[6] << 8) |
313 | | (unsigned int)aiv[7]; |
314 | if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) { |
315 | OPENSSL_cleanse(out, inlen); |
316 | return 0; |
317 | } |
318 | |
319 | /* |
320 | * Check that the rightmost padding_len octets of the output data are |
321 | * zero. |
322 | */ |
323 | padding_len = padded_len - ptext_len; |
324 | if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) { |
325 | OPENSSL_cleanse(out, inlen); |
326 | return 0; |
327 | } |
328 | |
329 | /* Section 4.2 step 3: Remove padding */ |
330 | return ptext_len; |
331 | } |
332 | |