dist/wpa/src/crypto/aes_wrap.c

   1 /*
   2  * AES-based functions
   3  *
   4  * - AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
   5  * - One-Key CBC MAC (OMAC1, i.e., CMAC) 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) 2003-2007, 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 #ifndef CONFIG_NO_AES_WRAP
  29
  30 /**
  31  * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
  32  * @kek: 16-octet Key encryption key (KEK)
  33  * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
  34  * bytes
  35  * @plain: Plaintext key to be wrapped, n * 64 bits
  36  * @cipher: Wrapped key, (n + 1) * 64 bits
  37  * Returns: 0 on success, -1 on failure
  38  */
  39 int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
  40 {
  41         u8 *a, *r, b[16];
  42         int i, j;
  43         void *ctx;
  44
  45         a = cipher;
  46         r = cipher + 8;
  47
  48         /* 1) Initialize variables. */
  49         os_memset(a, 0xa6, 8);
  50         os_memcpy(r, plain, 8 * n);
  51
  52         ctx = aes_encrypt_init(kek, 16);
  53         if (ctx == NULL)
  54                 return -1;
  55
  56         /* 2) Calculate intermediate values.
  57          * For j = 0 to 5
  58          *     For i=1 to n
  59          *         B = AES(K, A | R[i])
  60          *         A = MSB(64, B) ^ t where t = (n*j)+i
  61          *         R[i] = LSB(64, B)
  62          */
  63         for (j = 0; j <= 5; j++) {
  64                 r = cipher + 8;
  65                 for (i = 1; i <= n; i++) {
  66                         os_memcpy(b, a, 8);
  67                         os_memcpy(b + 8, r, 8);
  68                         aes_encrypt(ctx, b, b);
  69                         os_memcpy(a, b, 8);
  70                         a[7] ^= n * j + i;
  71                         os_memcpy(r, b + 8, 8);
  72                         r += 8;
  73                 }
  74         }
  75         aes_encrypt_deinit(ctx);
  76
  77         /* 3) Output the results.
  78          *
  79          * These are already in @cipher due to the location of temporary
  80          * variables.
  81          */
  82
  83         return 0;
  84 }
  85
  86 #endif /* CONFIG_NO_AES_WRAP */
  87
  88
  89 /**
  90  * aes_unwrap - Unwrap key with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
  91  * @kek: Key encryption key (KEK)
  92  * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
  93  * bytes
  94  * @cipher: Wrapped key to be unwrapped, (n + 1) * 64 bits
  95  * @plain: Plaintext key, n * 64 bits
  96  * Returns: 0 on success, -1 on failure (e.g., integrity verification failed)
  97  */
  98 int aes_unwrap(const u8 *kek, int n, const u8 *cipher, u8 *plain)
  99 {
 100         u8 a[8], *r, b[16];
 101         int i, j;
 102         void *ctx;
 103
 104         /* 1) Initialize variables. */
 105         os_memcpy(a, cipher, 8);
 106         r = plain;
 107         os_memcpy(r, cipher + 8, 8 * n);
 108
 109         ctx = aes_decrypt_init(kek, 16);
 110         if (ctx == NULL)
 111                 return -1;
 112
 113         /* 2) Compute intermediate values.
 114          * For j = 5 to 0
 115          *     For i = n to 1
 116          *         B = AES-1(K, (A ^ t) | R[i]) where t = n*j+i
 117          *         A = MSB(64, B)
 118          *         R[i] = LSB(64, B)
 119          */
 120         for (j = 5; j >= 0; j--) {
 121                 r = plain + (n - 1) * 8;
 122                 for (i = n; i >= 1; i--) {
 123                         os_memcpy(b, a, 8);
 124                         b[7] ^= n * j + i;
 125
 126                         os_memcpy(b + 8, r, 8);
 127                         aes_decrypt(ctx, b, b);
 128                         os_memcpy(a, b, 8);
 129                         os_memcpy(r, b + 8, 8);
 130                         r -= 8;
 131                 }
 132         }
 133         aes_decrypt_deinit(ctx);
 134
 135         /* 3) Output results.
 136          *
 137          * These are already in @plain due to the location of temporary
 138          * variables. Just verify that the IV matches with the expected value.
 139          */
 140         for (i = 0; i < 8; i++) {
 141                 if (a[i] != 0xa6)
 142                         return -1;
 143         }
 144
 145         return 0;
 146 }
 147
 148
 149 #define BLOCK_SIZE 16
 150
 151 #ifndef CONFIG_NO_AES_OMAC1
 152
 153 static void gf_mulx(u8 *pad)
 154 {
 155         int i, carry;
 156
 157         carry = pad[0] & 0x80;
 158         for (i = 0; i < BLOCK_SIZE - 1; i++)
 159                 pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
 160         pad[BLOCK_SIZE - 1] <<= 1;
 161         if (carry)
 162                 pad[BLOCK_SIZE - 1] ^= 0x87;
 163 }
 164
 165
 166 /**
 167  * omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
 168  * @key: 128-bit key for the hash operation
 169  * @num_elem: Number of elements in the data vector
 170  * @addr: Pointers to the data areas
 171  * @len: Lengths of the data blocks
 172  * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
 173  * Returns: 0 on success, -1 on failure
 174  *
 175  * This is a mode for using block cipher (AES in this case) for authentication.
 176  * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
 177  * (SP) 800-38B.
 178  */
 179 int omac1_aes_128_vector(const u8 *key, size_t num_elem,
 180                          const u8 *addr[], const size_t *len, u8 *mac)
 181 {
 182         void *ctx;
 183         u8 cbc[BLOCK_SIZE], pad[BLOCK_SIZE];
 184         const u8 *pos, *end;
 185         size_t i, e, left, total_len;
 186
 187         ctx = aes_encrypt_init(key, 16);
 188         if (ctx == NULL)
 189                 return -1;
 190         os_memset(cbc, 0, BLOCK_SIZE);
 191
 192         total_len = 0;
 193         for (e = 0; e < num_elem; e++)
 194                 total_len += len[e];
 195         left = total_len;
 196
 197         e = 0;
 198         pos = addr[0];
 199         end = pos + len[0];
 200
 201         while (left >= BLOCK_SIZE) {
 202                 for (i = 0; i < BLOCK_SIZE; i++) {
 203                         cbc[i] ^= *pos++;
 204                         if (pos >= end) {
 205                                 e++;
 206                                 pos = addr[e];
 207                                 end = pos + len[e];
 208                         }
 209                 }
 210                 if (left > BLOCK_SIZE)
 211                         aes_encrypt(ctx, cbc, cbc);
 212                 left -= BLOCK_SIZE;
 213         }
 214
 215         os_memset(pad, 0, BLOCK_SIZE);
 216         aes_encrypt(ctx, pad, pad);
 217         gf_mulx(pad);
 218
 219         if (left || total_len == 0) {
 220                 for (i = 0; i < left; i++) {
 221                         cbc[i] ^= *pos++;
 222                         if (pos >= end) {
 223                                 e++;
 224                                 pos = addr[e];
 225                                 end = pos + len[e];
 226                         }
 227                 }
 228                 cbc[left] ^= 0x80;
 229                 gf_mulx(pad);
 230         }
 231
 232         for (i = 0; i < BLOCK_SIZE; i++)
 233                 pad[i] ^= cbc[i];
 234         aes_encrypt(ctx, pad, mac);
 235         aes_encrypt_deinit(ctx);
 236         return 0;
 237 }
 238
 239
 240 /**
 241  * omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
 242  * @key: 128-bit key for the hash operation
 243  * @data: Data buffer for which a MAC is determined
 244  * @data_len: Length of data buffer in bytes
 245  * @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
 246  * Returns: 0 on success, -1 on failure
 247  *
 248  * This is a mode for using block cipher (AES in this case) for authentication.
 249  * OMAC1 was standardized with the name CMAC by NIST in a Special Publication
 250  * (SP) 800-38B.
 251  */
 252 int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
 253 {
 254         return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
 255 }
 256
 257 #endif /* CONFIG_NO_AES_OMAC1 */
 258
 259
 260 #ifndef CONFIG_NO_AES_ENCRYPT_BLOCK
 261 /**
 262  * aes_128_encrypt_block - Perform one AES 128-bit block operation
 263  * @key: Key for AES
 264  * @in: Input data (16 bytes)
 265  * @out: Output of the AES block operation (16 bytes)
 266  * Returns: 0 on success, -1 on failure
 267  */
 268 int aes_128_encrypt_block(const u8 *key, const u8 *in, u8 *out)
 269 {
 270         void *ctx;
 271         ctx = aes_encrypt_init(key, 16);
 272         if (ctx == NULL)
 273                 return -1;
 274         aes_encrypt(ctx, in, out);
 275         aes_encrypt_deinit(ctx);
 276         return 0;
 277 }
 278 #endif /* CONFIG_NO_AES_ENCRYPT_BLOCK */
 279
 280
 281 #ifndef CONFIG_NO_AES_CTR
 282
 283 /**
 284  * aes_128_ctr_encrypt - AES-128 CTR mode encryption
 285  * @key: Key for encryption (16 bytes)
 286  * @nonce: Nonce for counter mode (16 bytes)
 287  * @data: Data to encrypt in-place
 288  * @data_len: Length of data in bytes
 289  * Returns: 0 on success, -1 on failure
 290  */
 291 int aes_128_ctr_encrypt(const u8 *key, const u8 *nonce,
 292                         u8 *data, size_t data_len)
 293 {
 294         void *ctx;
 295         size_t j, len, left = data_len;
 296         int i;
 297         u8 *pos = data;
 298         u8 counter[BLOCK_SIZE], buf[BLOCK_SIZE];
 299
 300         ctx = aes_encrypt_init(key, 16);
 301         if (ctx == NULL)
 302                 return -1;
 303         os_memcpy(counter, nonce, BLOCK_SIZE);
 304
 305         while (left > 0) {
 306                 aes_encrypt(ctx, counter, buf);
 307
 308                 len = (left < BLOCK_SIZE) ? left : BLOCK_SIZE;
 309                 for (j = 0; j < len; j++)
 310                         pos[j] ^= buf[j];
 311                 pos += len;
 312                 left -= len;
 313
 314                 for (i = BLOCK_SIZE - 1; i >= 0; i--) {
 315                         counter[i]++;
 316                         if (counter[i])
 317                                 break;
 318                 }
 319         }
 320         aes_encrypt_deinit(ctx);
 321         return 0;
 322 }
 323
 324 #endif /* CONFIG_NO_AES_CTR */
 325
 326
 327 #ifndef CONFIG_NO_AES_EAX
 328
 329 /**
 330  * aes_128_eax_encrypt - AES-128 EAX mode encryption
 331  * @key: Key for encryption (16 bytes)
 332  * @nonce: Nonce for counter mode
 333  * @nonce_len: Nonce length in bytes
 334  * @hdr: Header data to be authenticity protected
 335  * @hdr_len: Length of the header data bytes
 336  * @data: Data to encrypt in-place
 337  * @data_len: Length of data in bytes
 338  * @tag: 16-byte tag value
 339  * Returns: 0 on success, -1 on failure
 340  */
 341 int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
 342                         const u8 *hdr, size_t hdr_len,
 343                         u8 *data, size_t data_len, u8 *tag)
 344 {
 345         u8 *buf;
 346         size_t buf_len;
 347         u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
 348         int i, ret = -1;
 349
 350         if (nonce_len > data_len)
 351                 buf_len = nonce_len;
 352         else
 353                 buf_len = data_len;
 354         if (hdr_len > buf_len)
 355                 buf_len = hdr_len;
 356         buf_len += 16;
 357
 358         buf = os_malloc(buf_len);
 359         if (buf == NULL)
 360                 return -1;
 361
 362         os_memset(buf, 0, 15);
 363
 364         buf[15] = 0;
 365         os_memcpy(buf + 16, nonce, nonce_len);
 366         if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac))
 367                 goto fail;
 368
 369         buf[15] = 1;
 370         os_memcpy(buf + 16, hdr, hdr_len);
 371         if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac))
 372                 goto fail;
 373
 374         if (aes_128_ctr_encrypt(key, nonce_mac, data, data_len))
 375                 goto fail;
 376         buf[15] = 2;
 377         os_memcpy(buf + 16, data, data_len);
 378         if (omac1_aes_128(key, buf, 16 + data_len, data_mac))
 379                 goto fail;
 380
 381         for (i = 0; i < BLOCK_SIZE; i++)
 382                 tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i];
 383
 384         ret = 0;
 385 fail:
 386         os_free(buf);
 387
 388         return ret;
 389 }
 390
 391
 392 /**
 393  * aes_128_eax_decrypt - AES-128 EAX mode decryption
 394  * @key: Key for decryption (16 bytes)
 395  * @nonce: Nonce for counter mode
 396  * @nonce_len: Nonce length in bytes
 397  * @hdr: Header data to be authenticity protected
 398  * @hdr_len: Length of the header data bytes
 399  * @data: Data to encrypt in-place
 400  * @data_len: Length of data in bytes
 401  * @tag: 16-byte tag value
 402  * Returns: 0 on success, -1 on failure, -2 if tag does not match
 403  */
 404 int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
 405                         const u8 *hdr, size_t hdr_len,
 406                         u8 *data, size_t data_len, const u8 *tag)
 407 {
 408         u8 *buf;
 409         size_t buf_len;
 410         u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
 411         int i;
 412
 413         if (nonce_len > data_len)
 414                 buf_len = nonce_len;
 415         else
 416                 buf_len = data_len;
 417         if (hdr_len > buf_len)
 418                 buf_len = hdr_len;
 419         buf_len += 16;
 420
 421         buf = os_malloc(buf_len);
 422         if (buf == NULL)
 423                 return -1;
 424
 425         os_memset(buf, 0, 15);
 426
 427         buf[15] = 0;
 428         os_memcpy(buf + 16, nonce, nonce_len);
 429         if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) {
 430                 os_free(buf);
 431                 return -1;
 432         }
 433
 434         buf[15] = 1;
 435         os_memcpy(buf + 16, hdr, hdr_len);
 436         if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) {
 437                 os_free(buf);
 438                 return -1;
 439         }
 440
 441         buf[15] = 2;
 442         os_memcpy(buf + 16, data, data_len);
 443         if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) {
 444                 os_free(buf);
 445                 return -1;
 446         }
 447
 448         os_free(buf);
 449
 450         for (i = 0; i < BLOCK_SIZE; i++) {
 451                 if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]))
 452                         return -2;
 453         }
 454
 455         return aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
 456 }
 457
 458 #endif /* CONFIG_NO_AES_EAX */
 459
 460
 461 #ifndef CONFIG_NO_AES_CBC
 462
 463 /**
 464  * aes_128_cbc_encrypt - AES-128 CBC encryption
 465  * @key: Encryption key
 466  * @iv: Encryption IV for CBC mode (16 bytes)
 467  * @data: Data to encrypt in-place
 468  * @data_len: Length of data in bytes (must be divisible by 16)
 469  * Returns: 0 on success, -1 on failure
 470  */
 471 int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
 472 {
 473         void *ctx;
 474         u8 cbc[BLOCK_SIZE];
 475         u8 *pos = data;
 476         int i, j, blocks;
 477
 478         ctx = aes_encrypt_init(key, 16);
 479         if (ctx == NULL)
 480                 return -1;
 481         os_memcpy(cbc, iv, BLOCK_SIZE);
 482
 483         blocks = data_len / BLOCK_SIZE;
 484         for (i = 0; i < blocks; i++) {
 485                 for (j = 0; j < BLOCK_SIZE; j++)
 486                         cbc[j] ^= pos[j];
 487                 aes_encrypt(ctx, cbc, cbc);
 488                 os_memcpy(pos, cbc, BLOCK_SIZE);
 489                 pos += BLOCK_SIZE;
 490         }
 491         aes_encrypt_deinit(ctx);
 492         return 0;
 493 }
 494
 495
 496 /**
 497  * aes_128_cbc_decrypt - AES-128 CBC decryption
 498  * @key: Decryption key
 499  * @iv: Decryption IV for CBC mode (16 bytes)
 500  * @data: Data to decrypt in-place
 501  * @data_len: Length of data in bytes (must be divisible by 16)
 502  * Returns: 0 on success, -1 on failure
 503  */
 504 int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
 505 {
 506         void *ctx;
 507         u8 cbc[BLOCK_SIZE], tmp[BLOCK_SIZE];
 508         u8 *pos = data;
 509         int i, j, blocks;
 510
 511         ctx = aes_decrypt_init(key, 16);
 512         if (ctx == NULL)
 513                 return -1;
 514         os_memcpy(cbc, iv, BLOCK_SIZE);
 515
 516         blocks = data_len / BLOCK_SIZE;
 517         for (i = 0; i < blocks; i++) {
 518                 os_memcpy(tmp, pos, BLOCK_SIZE);
 519                 aes_decrypt(ctx, pos, pos);
 520                 for (j = 0; j < BLOCK_SIZE; j++)
 521                         pos[j] ^= cbc[j];
 522                 os_memcpy(cbc, tmp, BLOCK_SIZE);
 523                 pos += BLOCK_SIZE;
 524         }
 525         aes_decrypt_deinit(ctx);
 526         return 0;
 527 }
 528
 529 #endif /* CONFIG_NO_AES_CBC */