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 */
CRYPTO_128_wrap(void * key,const unsigned char * iv,unsigned char * out,const unsigned char * in,size_t inlen,block128_f block)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 */
crypto_128_unwrap_raw(void * key,unsigned char * iv,unsigned char * out,const unsigned char * in,size_t inlen,block128_f block)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 */
CRYPTO_128_unwrap(void * key,const unsigned char * iv,unsigned char * out,const unsigned char * in,size_t inlen,block128_f block)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 */
CRYPTO_128_wrap_pad(void * key,const unsigned char * icv,unsigned char * out,const unsigned char * in,size_t inlen,block128_f block)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 */
CRYPTO_128_unwrap_pad(void * key,const unsigned char * icv,unsigned char * out,const unsigned char * in,size_t inlen,block128_f block)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
