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 */
234 const size_t blocks_padded = (inlen + 8) / 8;
235 const size_t padded_len = blocks_padded * 8;
236 const size_t padding_len = padded_len - inlen;
237 /* RFC 5649 section 3: Alternative Initial Value */
238 unsigned char aiv[8];
241 /* Section 1: use 32-bit fixed field for plaintext octet length */
242 if (inlen == 0 || inlen >= CRYPTO128_WRAP_MAX)
245 /* Section 3: Alternative Initial Value */
247 memcpy(aiv, default_aiv, 4);
249 memcpy(aiv, icv, 4); /* Standard doesn't mention this. */
251 aiv[4] = (inlen >> 24) & 0xFF;
252 aiv[5] = (inlen >> 16) & 0xFF;
253 aiv[6] = (inlen >> 8) & 0xFF;
254 aiv[7] = inlen & 0xFF;
256 if (padded_len == 8) {
258 * Section 4.1 - special case in step 2: If the padded plaintext
259 * contains exactly eight octets, then prepend the AIV and encrypt
260 * the resulting 128-bit block using AES in ECB mode.
262 memmove(out + 8, in, inlen);
264 memset(out + 8 + inlen, 0, padding_len);
265 block(out, out, key);
266 ret = 16; /* AIV + padded input */
268 memmove(out, in, inlen);
269 memset(out + inlen, 0, padding_len); /* Section 4.1 step 1 */
270 ret = CRYPTO_128_wrap(key, aiv, out, out, padded_len, block);
276 /** Unwrapping according to RFC 5649 section 4.2.
278 * @param[in] key Key value.
279 * @param[in] icv (Non-standard) IV, 4 bytes. NULL = use default_aiv.
280 * @param[out] out Plain text. Minimal buffer length = inlen bytes.
281 * Input and output buffers can overlap if block function
283 * @param[in] in Ciphertext text as n 64-bit blocks
284 * @param[in] inlen Length of in.
285 * @param[in] block Block processing function.
286 * @return 0 if inlen is out of range [16, CRYPTO128_WRAP_MAX],
287 * or if inlen is not multiply of 8
288 * or if IV and message length indicator doesn't match.
289 * Output length if unwrapping succeeded and IV matches.
291 size_t CRYPTO_128_unwrap_pad(void *key, const unsigned char *icv,
293 const unsigned char *in, size_t inlen,
296 /* n: number of 64-bit blocks in the padded key data */
297 size_t n = inlen / 8 - 1;
301 /* RFC 5649 section 3: Alternative Initial Value */
302 unsigned char aiv[8];
303 static unsigned char zeros[8] = { 0x0 };
306 /* Section 4.2: Cipher text length has to be (n+1) 64-bit blocks. */
307 if ((inlen & 0x7) != 0 || inlen < 16 || inlen >= CRYPTO128_WRAP_MAX)
310 memmove(out, in, inlen);
313 * Section 4.2 - special case in step 1: When n=1, the ciphertext
314 * contains exactly two 64-bit blocks and they are decrypted as a
315 * single AES block using AES in ECB mode: AIV | P[1] = DEC(K, C[0] |
318 block(out, out, key);
321 memmove(out, out + 8, 8);
324 padded_len = inlen - 8;
325 ret = crypto_128_unwrap_raw(key, aiv, out, out, inlen, block);
326 if (padded_len != ret) {
327 OPENSSL_cleanse(out, inlen);
333 * Section 3: AIV checks: Check that MSB(32,A) = A65959A6. Optionally a
334 * user-supplied value can be used (even if standard doesn't mention
337 if ((!icv && CRYPTO_memcmp(aiv, default_aiv, 4))
338 || (icv && CRYPTO_memcmp(aiv, icv, 4))) {
339 OPENSSL_cleanse(out, inlen);
344 * Check that 8*(n-1) < LSB(32,AIV) <= 8*n. If so, let ptext_len =
348 ptext_len = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | aiv[7];
349 if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
350 OPENSSL_cleanse(out, inlen);
355 * Check that the rightmost padding_len octets of the output data are
358 padding_len = padded_len - ptext_len;
359 if (CRYPTO_memcmp(out + ptext_len, zeros, padding_len) != 0) {
360 OPENSSL_cleanse(out, inlen);
364 /* Section 4.2 step 3: Remove padding */