1 /* crypto/modes/wrap128.c */
3 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
4 * project. Mode with padding contributed by Petr Spacek
5 * (pspacek@redhat.com).
7 /* ====================================================================
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53 * ====================================================================
58 * Following wrapping modes were designed for AES but this implementation
59 * allows you to use them for any 128 bit block cipher.
63 #include <openssl/modes.h>
65 /** RFC 3394 section 2.2.3.1 Default Initial Value */
66 static const unsigned char default_iv[] = {
67 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6,
70 /** RFC 5649 section 3 Alternative Initial Value 32-bit constant */
71 static const unsigned char default_aiv[] = {
72 0xA6, 0x59, 0x59, 0xA6
75 /** Input size limit: lower than maximum of standards but far larger than
76 * anything that will be used in practice.
78 #define CRYPTO128_WRAP_MAX (1UL << 31)
80 /** Wrapping according to RFC 3394 section 2.2.1.
82 * @param[in] key Key value.
83 * @param[in] iv IV value. Length = 8 bytes. NULL = use default_iv.
84 * @param[in] in Plain text as n 64-bit blocks, n >= 2.
85 * @param[in] inlen Length of in.
86 * @param[out] out Cipher text. Minimal buffer length = (inlen + 8) bytes.
87 * Input and output buffers can overlap if block function
89 * @param[in] block Block processing function.
90 * @return 0 if inlen does not consist of n 64-bit blocks, n >= 2.
91 * or if inlen > CRYPTO128_WRAP_MAX.
92 * Output length if wrapping succeeded.
94 size_t CRYPTO_128_wrap(void *key, const unsigned char *iv,
96 const unsigned char *in, size_t inlen,
99 unsigned char *A, B[16], *R;
101 if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
105 memmove(out + 8, in, inlen);
111 for (j = 0; j < 6; j++) {
113 for (i = 0; i < inlen; i += 8, t++, R += 8) {
116 A[7] ^= (unsigned char)(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);
129 /** Unwrapping according to RFC 3394 section 2.2.2 steps 1-2.
130 * IV check (step 3) is responsibility of the caller.
132 * @param[in] key Key value.
133 * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes.
134 * @param[out] out Plain text without IV.
135 * Minimal buffer length = (inlen - 8) bytes.
136 * Input and output buffers can overlap if block function
138 * @param[in] in Ciphertext text as n 64-bit blocks
139 * @param[in] inlen Length of in.
140 * @param[in] block Block processing function.
141 * @return 0 if inlen is out of range [24, CRYPTO128_WRAP_MAX]
142 * or if inlen is not multiply of 8.
143 * Output length otherwise.
145 static size_t crypto_128_unwrap_raw(void *key, unsigned char *iv,
147 const unsigned char *in, size_t inlen,
150 unsigned char *A, B[16], *R;
153 if ((inlen & 0x7) || (inlen < 16) || (inlen > CRYPTO128_WRAP_MAX))
156 t = 6 * (inlen >> 3);
158 memmove(out, in + 8, inlen);
159 for (j = 0; j < 6; j++) {
161 for (i = 0; i < inlen; i += 8, t--, R -= 8) {
162 A[7] ^= (unsigned char)(t & 0xff);
164 A[6] ^= (unsigned char)((t >> 8) & 0xff);
165 A[5] ^= (unsigned char)((t >> 16) & 0xff);
166 A[4] ^= (unsigned char)((t >> 24) & 0xff);
177 /** Unwrapping according to RFC 3394 section 2.2.2 including IV check.
178 * First block of plain text have to match supplied IV otherwise an error is
181 * @param[in] key Key value.
182 * @param[out] iv Unchecked IV value. Minimal buffer length = 8 bytes.
183 * @param[out] out Plain text without IV.
184 * Minimal buffer length = (inlen - 8) bytes.
185 * Input and output buffers can overlap if block function
187 * @param[in] in Ciphertext text 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 multiply 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(out, iv, 8)) {
209 OPENSSL_cleanse(out, inlen);
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 Cipher text. Minimal buffer length = (inlen + 15) bytes.
220 * Input and output buffers can overlap if block function
222 * @param[in] in Plain text 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 Plain text. Minimal buffer length = inlen bytes.
286 * Input and output buffers can overlap if block function
288 * @param[in] in Ciphertext text 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 multiply 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: Cipher text 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 = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | aiv[7];
354 if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
355 OPENSSL_cleanse(out, inlen);
360 * Check that the rightmost padding_len octets of the output data are
363 padding_len = padded_len - ptext_len;
364 if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
365 OPENSSL_cleanse(out, inlen);
369 /* Section 4.2 step 3: Remove padding */