Dmitry Shmidt | 8d520ff | 2011-05-09 14:06:53 -0700 | [diff] [blame] | 1 | /* |
| 2 | * AES Key Wrap Algorithm (128-bit KEK) (RFC3394) |
| 3 | * |
| 4 | * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | * |
| 10 | * Alternatively, this software may be distributed under the terms of BSD |
| 11 | * license. |
| 12 | * |
| 13 | * See README and COPYING for more details. |
| 14 | */ |
| 15 | |
| 16 | #include "includes.h" |
| 17 | |
| 18 | #include "common.h" |
| 19 | #include "aes.h" |
| 20 | #include "aes_wrap.h" |
| 21 | |
| 22 | /** |
| 23 | * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394) |
| 24 | * @kek: 16-octet Key encryption key (KEK) |
| 25 | * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16 |
| 26 | * bytes |
| 27 | * @plain: Plaintext key to be wrapped, n * 64 bits |
| 28 | * @cipher: Wrapped key, (n + 1) * 64 bits |
| 29 | * Returns: 0 on success, -1 on failure |
| 30 | */ |
| 31 | int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher) |
| 32 | { |
| 33 | u8 *a, *r, b[16]; |
| 34 | int i, j; |
| 35 | void *ctx; |
| 36 | |
| 37 | a = cipher; |
| 38 | r = cipher + 8; |
| 39 | |
| 40 | /* 1) Initialize variables. */ |
| 41 | os_memset(a, 0xa6, 8); |
| 42 | os_memcpy(r, plain, 8 * n); |
| 43 | |
| 44 | ctx = aes_encrypt_init(kek, 16); |
| 45 | if (ctx == NULL) |
| 46 | return -1; |
| 47 | |
| 48 | /* 2) Calculate intermediate values. |
| 49 | * For j = 0 to 5 |
| 50 | * For i=1 to n |
| 51 | * B = AES(K, A | R[i]) |
| 52 | * A = MSB(64, B) ^ t where t = (n*j)+i |
| 53 | * R[i] = LSB(64, B) |
| 54 | */ |
| 55 | for (j = 0; j <= 5; j++) { |
| 56 | r = cipher + 8; |
| 57 | for (i = 1; i <= n; i++) { |
| 58 | os_memcpy(b, a, 8); |
| 59 | os_memcpy(b + 8, r, 8); |
| 60 | aes_encrypt(ctx, b, b); |
| 61 | os_memcpy(a, b, 8); |
| 62 | a[7] ^= n * j + i; |
| 63 | os_memcpy(r, b + 8, 8); |
| 64 | r += 8; |
| 65 | } |
| 66 | } |
| 67 | aes_encrypt_deinit(ctx); |
| 68 | |
| 69 | /* 3) Output the results. |
| 70 | * |
| 71 | * These are already in @cipher due to the location of temporary |
| 72 | * variables. |
| 73 | */ |
| 74 | |
| 75 | return 0; |
| 76 | } |