1 /* 2 * Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (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