2 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3 * project. Mode with padding contributed by Petr Spacek
4 * (pspacek@redhat.com).
6 /* ====================================================================
7 * Copyright (c) 2013 The OpenSSL Project. All rights reserved.
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52 * ====================================================================
57 * Following wrapping modes were designed for AES but this implementation
58 * allows you to use them for any 128 bit block cipher.
61 #include "internal/cryptlib.h"
62 #include <openssl/modes.h>
64 /** RFC 3394 section 2.2.3.1 Default Initial Value */
65 static const unsigned char default_iv[] = {
66 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
69 /** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
70 static const unsigned char default_aiv[] = {
71 0xA6, 0x59, 0x59, 0xA6
74 /** Input size limit: lower than maximum of standards but far larger than
75 * anything that will be used in practice.
77 #define CRYPTO128_WRAP_MAX (1UL << 31)
79 /** Wrapping according to RFC 3394 section 2.2.1.
81 * @param[in] key Key value.
82 * @param[in] iv IV value. Length = 8 bytes. NULL = use default_iv.
83 * @param[in] in Plaintext as n 64-bit blocks, n >= 2.
84 * @param[in] inlen Length of in.
85 * @param[out] out Ciphertext. Minimal buffer length = (inlen + 8) bytes.
86 * Input and output buffers can overlap if block function
88 * @param[in] block Block processing function.
89 * @return 0 if inlen does not consist of n 64-bit blocks, n >= 2.
90 * or if inlen > CRYPTO128_WRAP_MAX.
91 * Output length if wrapping succeeded.
93 size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
95 const unsigned char *in, size_t inlen,
98 unsigned char *A, B[16], *R;
100 if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
104 memmove(out + 8, in, inlen);
110 for (j = 0; j < 6; j++) {
112 for (i = 0; i < inlen; i += 8, t++, R += 8) {
115 A[7] ^= (unsigned char)(t & 0xff);
117 A[6] ^= (unsigned char)((t >> 8) & 0xff);
118 A[5] ^= (unsigned char)((t >> 16) & 0xff);
119 A[4] ^= (unsigned char)((t >> 24) & 0xff);
128 /** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
129 * The IV check (step 3) is responsibility of the caller.
131 * @param[in] key Key value.
132 * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes.
133 * @param[out] out Plaintext without IV.
134 * Minimal buffer length = (inlen - 8) bytes.
135 * Input and output buffers can overlap if block function
137 * @param[in] in Ciphertext as n 64-bit blocks.
138 * @param[in] inlen Length of in.
139 * @param[in] block Block processing function.
140 * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
141 * or if inlen is not a multiple of 8.
142 * Output length otherwise.
144 static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
146 const unsigned char *in, size_t inlen,
149 unsigned char *A, B[16], *R;
152 if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
155 t = 6 * (inlen >> 3);
157 memmove(out, in + 8, inlen);
158 for (j = 0; j < 6; j++) {
160 for (i = 0; i < inlen; i += 8, t--, R -= 8) {
161 A[7] ^= (unsigned char)(t & 0xff);
163 A[6] ^= (unsigned char)((t >> 8) & 0xff);
164 A[5] ^= (unsigned char)((t >> 16) & 0xff);
165 A[4] ^= (unsigned char)((t >> 24) & 0xff);
176 /** Unwrapping according to RFC 3394 section 2.2.2, including the IV check.
177 * The first block of plaintext has to match the supplied IV, otherwise an
180 * @param[in] key Key value.
181 * @param[out] iv IV value to match against. Length = 8 bytes.
182 * NULL = use default_iv.
183 * @param[out] out Plaintext without IV.
184 * Minimal buffer length = (inlen - 8) bytes.
185 * Input and output buffers can overlap if block function
187 * @param[in] in Ciphertext as n 64-bit blocks.
188 * @param[in] inlen Length of in.
189 * @param[in] block Block processing function.
190 * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
191 * or if inlen is not a multiple of 8
192 * or if IV doesn't match expected value.
193 * Output length otherwise.
195 size_t CRYPTO_128_unwrap(void *key, const unsigned char *iv,
196 unsigned char *out, const unsigned char *in,
197 size_t inlen, block128_f block)
200 unsigned char got_iv[8];
202 ret = crypto_128_unwrap_raw(key, got_iv, out, in, inlen, block);
208 if (CRYPTO_memcmp(got_iv, iv, 8)) {
209 OPENSSL_cleanse(out, ret);
215 /** Wrapping according to RFC 5649 section 4.1.
217 * @param[in] key Key value.
218 * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv.
219 * @param[out] out Ciphertext. Minimal buffer length = (inlen + 15) bytes.
220 * Input and output buffers can overlap if block function
222 * @param[in] in Plaintext as n 64-bit blocks, n >= 2.
223 * @param[in] inlen Length of in.
224 * @param[in] block Block processing function.
225 * @return 0 if inlen is out of range [1, CRYPTO128_WRAP_MAX].
226 * Output length if wrapping succeeded.
228 size_t CRYPTO_128_wrap_pad(void *key, const unsigned char *icv,
230 const unsigned char *in, size_t inlen,
233 /* n: number of 64-bit blocks in the padded key data
235 * If length of plain text is not a multiple of 8, pad the plain text octet
236 * string on the right with octets of zeros, where final length is the
237 * smallest multiple of 8 that is greater than length of plain text.
238 * If length of plain text is a multiple of 8, then there is no padding. */
239 const size_t blocks_padded = (inlen + 7) / 8; /* CEILING(m/8) */
240 const size_t padded_len = blocks_padded * 8;
241 const size_t padding_len = padded_len - inlen;
242 /* RFC 5649 section 3: Alternative Initial Value */
243 unsigned char aiv[8];
246 /* Section 1: use 32-bit fixed field for plaintext octet length */
247 if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
250 /* Section 3: Alternative Initial Value */
252 memcpy(aiv, default_aiv, 4);
254 memcpy(aiv, icv, 4); /* Standard doesn't mention this. */
256 aiv[4] = (inlen >> 24) & 0xFF;
257 aiv[5] = (inlen >> 16) & 0xFF;
258 aiv[6] = (inlen >> 8) & 0xFF;
259 aiv[7] = inlen & 0xFF;
261 if (padded_len == 8) {
263 * Section 4.1 - special case in step 2: If the padded plaintext
264 * contains exactly eight octets, then prepend the AIV and encrypt
265 * the resulting 128-bit block using AES in ECB mode.
267 memmove(out + 8, in, inlen);
269 memset(out + 8 + inlen, 0, padding_len);
270 block(out, out, key);
271 ret = 16; /* AIV + padded input */
273 memmove(out, in, inlen);
274 memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
275 ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
281 /** Unwrapping according to RFC 5649 section 4.2.
283 * @param[in] key Key value.
284 * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv.
285 * @param[out] out Plaintext. Minimal buffer length = inlen bytes.
286 * Input and output buffers can overlap if block function
288 * @param[in] in Ciphertext as n 64-bit blocks.
289 * @param[in] inlen Length of in.
290 * @param[in] block Block processing function.
291 * @return 0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
292 * or if inlen is not a multiple of 8
293 * or if IV and message length indicator doesn't match.
294 * Output length if unwrapping succeeded and IV matches.
296 size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
298 const unsigned char *in, size_t inlen,
301 /* n: number of 64-bit blocks in the padded key data */
302 size_t n = inlen / 8 - 1;
306 /* RFC 5649 section 3: Alternative Initial Value */
307 unsigned char aiv[8];
308 static unsigned char zeros[8] = { 0x0 };
311 /* Section 4.2: Ciphertext length has to be (n+1) 64-bit blocks. */
312 if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
315 memmove(out, in, inlen);
318 * Section 4.2 - special case in step 1: When n=1, the ciphertext
319 * contains exactly two 64-bit blocks and they are decrypted as a
320 * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
323 block(out, out, key);
326 memmove(out, out + 8, 8);
329 padded_len = inlen - 8;
330 ret = crypto_128_unwrap_raw(key, aiv, out, out, inlen, block);
331 if (padded_len != ret) {
332 OPENSSL_cleanse(out, inlen);
338 * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
339 * user-supplied value can be used (even if standard doesn't mention
342 if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
343 || (icv && CRYPTO_memcmp(aiv, icv, 4))) {
344 OPENSSL_cleanse(out, inlen);
349 * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
353 ptext_len = ((unsigned int)aiv[4] << 24)
354 | ((unsigned int)aiv[5] << 16)
355 | ((unsigned int)aiv[6] << 8)
356 | (unsigned int)aiv[7];
357 if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
358 OPENSSL_cleanse(out, inlen);
363 * Check that the rightmost padding_len octets of the output data are
366 padding_len = padded_len - ptext_len;
367 if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
368 OPENSSL_cleanse(out, inlen);
372 /* Section 4.2 step 3: Remove padding */