contrib/hostapd-0.5.8/aes_wrap.c

   1 /*
   2  * AES-based functions
   3  *
   4  * - AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
   5  * - One-Key CBC MAC (OMAC1) hash with AES-128
   6  * - AES-128 CTR mode encryption
   7  * - AES-128 EAX mode encryption/decryption
   8  * - AES-128 CBC
   9  *
  10  * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  *
  16  * Alternatively, this software may be distributed under the terms of BSD
  17  * license.
  18  *
  19  * See README and COPYING for more details.
  20  */
  21
  22 #include "includes.h"
  23
  24 #include "common.h"
  25 #include "aes_wrap.h"
  26 #include "crypto.h"
  27
  28 #ifdef INTERNAL_AES
  29 #include "aes.c"
  30 #endif /* INTERNAL_AES */
  31
  32
  33 #ifndef CONFIG_NO_AES_WRAP
  34
  35 /**
  36  * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
  37  * @kek: Key encryption key (KEK)
  38  * @n: Length of the wrapped key in 64-bit units; e.g., 2 = 128-bit = 16 bytes
  39  * @plain: Plaintext key to be wrapped, n * 64 bit
  40  * @cipher: Wrapped key, (n + 1) * 64 bit
  41  * Returns: 0 on success, -1 on failure
  42  */
  43 int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
  44 {
  45         u8 *a, *r, b[16];
  46         int i, j;
  47         void *ctx;
  48
  49         a = cipher;
  50         r = cipher + 8;
  51
  52         /* 1) Initialize variables. */
  53         os_memset(a, 0xa6, 8);
  54         os_memcpy(r, plain, 8 * n);
  55
  56         ctx = aes_encrypt_init(kek, 16);
  57         if (ctx == NULL)
  58                 return -1;
  59
  60         /* 2) Calculate intermediate values.
  61          * For j = 0 to 5
  62          *     For i=1 to n
  63          *         B = AES(K, A | R[i])
  64          *         A = MSB(64, B) ^ t where t = (n*j)+i
  65          *         R[i] = LSB(64, B)
  66          */
  67         for (j = 0; j <= 5; j++) {
  68                 r = cipher + 8;
  69                 for (i = 1; i <= n; i++) {
  70                         os_memcpy(b, a, 8);
  71                         os_memcpy(b + 8, r, 8);
  72                         aes_encrypt(ctx, b, b);
  73                         os_memcpy(a, b, 8);
  74                         a[7] ^= n * j + i;
  75                         os_memcpy(r, b + 8, 8);
  76                         r += 8;
  77                 }
  78         }
  79         aes_encrypt_deinit(ctx);
  80
  81         /* 3) Output the results.
  82          *
  83          * These are already in @cipher due to the location of temporary
  84          * variables.
  85          */
  86
  87         return 0;
  88 }
  89
  90 #endif /* CONFIG_NO_AES_WRAP */
  91
  92
  93 /**
  94  * aes_unwrap - Unwrap key with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
  95  * @kek: Key encryption key (KEK)
  96  * @n: Length of the wrapped key in 64-bit units; e.g., 2 = 128-bit = 16 bytes
  97  * @cipher: Wrapped key to be unwrapped, (n + 1) * 64 bit
  98  * @plain: Plaintext key, n * 64 bit
  99  * Returns: 0 on success, -1 on failure (e.g., integrity verification failed)
 100  */
 101 int aes_unwrap(const u8 *kek, int n, const u8 *cipher, u8 *plain)
 102 {
 103         u8 a[8], *r, b[16];
 104         int i, j;
 105         void *ctx;
 106
 107         /* 1) Initialize variables. */
 108         os_memcpy(a, cipher, 8);
 109         r = plain;
 110         os_memcpy(r, cipher + 8, 8 * n);
 111
 112         ctx = aes_decrypt_init(kek, 16);
 113         if (ctx == NULL)
 114                 return -1;
 115
 116         /* 2) Compute intermediate values.
 117          * For j = 5 to 0
 118          *     For i = n to 1
 119          *         B = AES-1(K, (A ^ t) | R[i]) where t = n*j+i
 120          *         A = MSB(64, B)
 121          *         R[i] = LSB(64, B)
 122          */
 123         for (j = 5; j >= 0; j--) {
 124                 r = plain + (n - 1) * 8;
 125                 for (i = n; i >= 1; i--) {
 126                         os_memcpy(b, a, 8);
 127                         b[7] ^= n * j + i;
 128
 129                         os_memcpy(b + 8, r, 8);
 130                         aes_decrypt(ctx, b, b);
 131                         os_memcpy(a, b, 8);
 132                         os_memcpy(r, b + 8, 8);
 133                         r -= 8;
 134                 }
 135         }
 136         aes_decrypt_deinit(ctx);
 137
 138         /* 3) Output results.
 139          *
 140          * These are already in @plain due to the location of temporary
 141          * variables. Just verify that the IV matches with the expected value.
 142          */
 143         for (i = 0; i < 8; i++) {
 144                 if (a[i] != 0xa6)
 145                         return -1;
 146         }
 147
 148         return 0;
 149 }
 150
 151
 152 #define BLOCK_SIZE 16
 153
 154 #ifndef CONFIG_NO_AES_OMAC1
 155
 156 static void gf_mulx(u8 *pad)
 157 {
 158         int i, carry;
 159
 160         carry = pad[0] & 0x80;
 161         for (i = 0; i < BLOCK_SIZE - 1; i++)
 162                 pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
 163         pad[BLOCK_SIZE - 1] <<= 1;
 164         if (carry)
 165                 pad[BLOCK_SIZE - 1] ^= 0x87;
 166 }
 167
 168
 169 /**
 170  * omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
 171  * @key: 128-bit key for the hash operation
 172  * @data: Data buffer for which a MAC is determined
 173  * @data: Length of data buffer in bytes
 174  * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
 175  * Returns: 0 on success, -1 on failure
 176  */
 177 int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
 178 {
 179         void *ctx;
 180         u8 cbc[BLOCK_SIZE], pad[BLOCK_SIZE];
 181         const u8 *pos = data;
 182         size_t i, left = data_len;
 183
 184         ctx = aes_encrypt_init(key, 16);
 185         if (ctx == NULL)
 186                 return -1;
 187         os_memset(cbc, 0, BLOCK_SIZE);
 188
 189         while (left >= BLOCK_SIZE) {
 190                 for (i = 0; i < BLOCK_SIZE; i++)
 191                         cbc[i] ^= *pos++;
 192                 if (left > BLOCK_SIZE)
 193                         aes_encrypt(ctx, cbc, cbc);
 194                 left -= BLOCK_SIZE;
 195         }
 196
 197         os_memset(pad, 0, BLOCK_SIZE);
 198         aes_encrypt(ctx, pad, pad);
 199         gf_mulx(pad);
 200
 201         if (left || data_len == 0) {
 202                 for (i = 0; i < left; i++)
 203                         cbc[i] ^= *pos++;
 204                 cbc[left] ^= 0x80;
 205                 gf_mulx(pad);
 206         }
 207
 208         for (i = 0; i < BLOCK_SIZE; i++)
 209                 pad[i] ^= cbc[i];
 210         aes_encrypt(ctx, pad, mac);
 211         aes_encrypt_deinit(ctx);
 212         return 0;
 213 }
 214
 215 #endif /* CONFIG_NO_AES_OMAC1 */
 216
 217
 218 /**
 219  * aes_128_encrypt_block - Perform one AES 128-bit block operation
 220  * @key: Key for AES
 221  * @in: Input data (16 bytes)
 222  * @out: Output of the AES block operation (16 bytes)
 223  * Returns: 0 on success, -1 on failure
 224  */
 225 int aes_128_encrypt_block(const u8 *key, const u8 *in, u8 *out)
 226 {
 227         void *ctx;
 228         ctx = aes_encrypt_init(key, 16);
 229         if (ctx == NULL)
 230                 return -1;
 231         aes_encrypt(ctx, in, out);
 232         aes_encrypt_deinit(ctx);
 233         return 0;
 234 }
 235
 236
 237 #ifndef CONFIG_NO_AES_CTR
 238
 239 /**
 240  * aes_128_ctr_encrypt - AES-128 CTR mode encryption
 241  * @key: Key for encryption (16 bytes)
 242  * @nonce: Nonce for counter mode (16 bytes)
 243  * @data: Data to encrypt in-place
 244  * @data_len: Length of data in bytes
 245  * Returns: 0 on success, -1 on failure
 246  */
 247 int aes_128_ctr_encrypt(const u8 *key, const u8 *nonce,
 248                         u8 *data, size_t data_len)
 249 {
 250         void *ctx;
 251         size_t j, len, left = data_len;
 252         int i;
 253         u8 *pos = data;
 254         u8 counter[BLOCK_SIZE], buf[BLOCK_SIZE];
 255
 256         ctx = aes_encrypt_init(key, 16);
 257         if (ctx == NULL)
 258                 return -1;
 259         os_memcpy(counter, nonce, BLOCK_SIZE);
 260
 261         while (left > 0) {
 262                 aes_encrypt(ctx, counter, buf);
 263
 264                 len = (left < BLOCK_SIZE) ? left : BLOCK_SIZE;
 265                 for (j = 0; j < len; j++)
 266                         pos[j] ^= buf[j];
 267                 pos += len;
 268                 left -= len;
 269
 270                 for (i = BLOCK_SIZE - 1; i >= 0; i--) {
 271                         counter[i]++;
 272                         if (counter[i])
 273                                 break;
 274                 }
 275         }
 276         aes_encrypt_deinit(ctx);
 277         return 0;
 278 }
 279
 280 #endif /* CONFIG_NO_AES_CTR */
 281
 282
 283 #ifndef CONFIG_NO_AES_EAX
 284
 285 /**
 286  * aes_128_eax_encrypt - AES-128 EAX mode encryption
 287  * @key: Key for encryption (16 bytes)
 288  * @nonce: Nonce for counter mode
 289  * @nonce_len: Nonce length in bytes
 290  * @hdr: Header data to be authenticity protected
 291  * @hdr_len: Length of the header data bytes
 292  * @data: Data to encrypt in-place
 293  * @data_len: Length of data in bytes
 294  * @tag: 16-byte tag value
 295  * Returns: 0 on success, -1 on failure
 296  */
 297 int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
 298                         const u8 *hdr, size_t hdr_len,
 299                         u8 *data, size_t data_len, u8 *tag)
 300 {
 301         u8 *buf;
 302         size_t buf_len;
 303         u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
 304         int i;
 305
 306         if (nonce_len > data_len)
 307                 buf_len = nonce_len;
 308         else
 309                 buf_len = data_len;
 310         if (hdr_len > buf_len)
 311                 buf_len = hdr_len;
 312         buf_len += 16;
 313
 314         buf = os_malloc(buf_len);
 315         if (buf == NULL)
 316                 return -1;
 317
 318         os_memset(buf, 0, 15);
 319
 320         buf[15] = 0;
 321         os_memcpy(buf + 16, nonce, nonce_len);
 322         omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac);
 323
 324         buf[15] = 1;
 325         os_memcpy(buf + 16, hdr, hdr_len);
 326         omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac);
 327
 328         aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
 329         buf[15] = 2;
 330         os_memcpy(buf + 16, data, data_len);
 331         omac1_aes_128(key, buf, 16 + data_len, data_mac);
 332
 333         os_free(buf);
 334
 335         for (i = 0; i < BLOCK_SIZE; i++)
 336                 tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i];
 337
 338         return 0;
 339 }
 340
 341
 342 /**
 343  * aes_128_eax_decrypt - AES-128 EAX mode decryption
 344  * @key: Key for decryption (16 bytes)
 345  * @nonce: Nonce for counter mode
 346  * @nonce_len: Nonce length in bytes
 347  * @hdr: Header data to be authenticity protected
 348  * @hdr_len: Length of the header data bytes
 349  * @data: Data to encrypt in-place
 350  * @data_len: Length of data in bytes
 351  * @tag: 16-byte tag value
 352  * Returns: 0 on success, -1 on failure, -2 if tag does not match
 353  */
 354 int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
 355                         const u8 *hdr, size_t hdr_len,
 356                         u8 *data, size_t data_len, const u8 *tag)
 357 {
 358         u8 *buf;
 359         size_t buf_len;
 360         u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
 361         int i;
 362
 363         if (nonce_len > data_len)
 364                 buf_len = nonce_len;
 365         else
 366                 buf_len = data_len;
 367         if (hdr_len > buf_len)
 368                 buf_len = hdr_len;
 369         buf_len += 16;
 370
 371         buf = os_malloc(buf_len);
 372         if (buf == NULL)
 373                 return -1;
 374
 375         os_memset(buf, 0, 15);
 376
 377         buf[15] = 0;
 378         os_memcpy(buf + 16, nonce, nonce_len);
 379         omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac);
 380
 381         buf[15] = 1;
 382         os_memcpy(buf + 16, hdr, hdr_len);
 383         omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac);
 384
 385         buf[15] = 2;
 386         os_memcpy(buf + 16, data, data_len);
 387         omac1_aes_128(key, buf, 16 + data_len, data_mac);
 388
 389         os_free(buf);
 390
 391         for (i = 0; i < BLOCK_SIZE; i++) {
 392                 if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]))
 393                         return -2;
 394         }
 395
 396         aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
 397
 398         return 0;
 399 }
 400
 401 #endif /* CONFIG_NO_AES_EAX */
 402
 403
 404 #ifndef CONFIG_NO_AES_CBC
 405
 406 /**
 407  * aes_128_cbc_encrypt - AES-128 CBC encryption
 408  * @key: Encryption key
 409  * @iv: Encryption IV for CBC mode (16 bytes)
 410  * @data: Data to encrypt in-place
 411  * @data_len: Length of data in bytes (must be divisible by 16)
 412  * Returns: 0 on success, -1 on failure
 413  */
 414 int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
 415 {
 416         void *ctx;
 417         u8 cbc[BLOCK_SIZE];
 418         u8 *pos = data;
 419         int i, j, blocks;
 420
 421         ctx = aes_encrypt_init(key, 16);
 422         if (ctx == NULL)
 423                 return -1;
 424         os_memcpy(cbc, iv, BLOCK_SIZE);
 425
 426         blocks = data_len / BLOCK_SIZE;
 427         for (i = 0; i < blocks; i++) {
 428                 for (j = 0; j < BLOCK_SIZE; j++)
 429                         cbc[j] ^= pos[j];
 430                 aes_encrypt(ctx, cbc, cbc);
 431                 os_memcpy(pos, cbc, BLOCK_SIZE);
 432                 pos += BLOCK_SIZE;
 433         }
 434         aes_encrypt_deinit(ctx);
 435         return 0;
 436 }
 437
 438
 439 /**
 440  * aes_128_cbc_decrypt - AES-128 CBC decryption
 441  * @key: Decryption key
 442  * @iv: Decryption IV for CBC mode (16 bytes)
 443  * @data: Data to decrypt in-place
 444  * @data_len: Length of data in bytes (must be divisible by 16)
 445  * Returns: 0 on success, -1 on failure
 446  */
 447 int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
 448 {
 449         void *ctx;
 450         u8 cbc[BLOCK_SIZE], tmp[BLOCK_SIZE];
 451         u8 *pos = data;
 452         int i, j, blocks;
 453
 454         ctx = aes_decrypt_init(key, 16);
 455         if (ctx == NULL)
 456                 return -1;
 457         os_memcpy(cbc, iv, BLOCK_SIZE);
 458
 459         blocks = data_len / BLOCK_SIZE;
 460         for (i = 0; i < blocks; i++) {
 461                 os_memcpy(tmp, pos, BLOCK_SIZE);
 462                 aes_decrypt(ctx, pos, pos);
 463                 for (j = 0; j < BLOCK_SIZE; j++)
 464                         pos[j] ^= cbc[j];
 465                 os_memcpy(cbc, tmp, BLOCK_SIZE);
 466                 pos += BLOCK_SIZE;
 467         }
 468         aes_decrypt_deinit(ctx);
 469         return 0;
 470 }
 471
 472 #endif /* CONFIG_NO_AES_CBC */