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Dmitry Shmidt8d520ff2011-05-09 14:06:53 -07001/*
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 */
31int 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}