1214501Srpaulo/*
2214501Srpaulo * AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
3214501Srpaulo *
4214501Srpaulo * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
5214501Srpaulo *
6214501Srpaulo * This program is free software; you can redistribute it and/or modify
7214501Srpaulo * it under the terms of the GNU General Public License version 2 as
8214501Srpaulo * published by the Free Software Foundation.
9214501Srpaulo *
10214501Srpaulo * Alternatively, this software may be distributed under the terms of BSD
11214501Srpaulo * license.
12214501Srpaulo *
13214501Srpaulo * See README and COPYING for more details.
14214501Srpaulo */
15214501Srpaulo
16214501Srpaulo#include "includes.h"
17214501Srpaulo
18214501Srpaulo#include "common.h"
19214501Srpaulo#include "aes.h"
20214501Srpaulo#include "aes_wrap.h"
21214501Srpaulo
22214501Srpaulo/**
23214501Srpaulo * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
24214501Srpaulo * @kek: 16-octet Key encryption key (KEK)
25214501Srpaulo * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
26214501Srpaulo * bytes
27214501Srpaulo * @plain: Plaintext key to be wrapped, n * 64 bits
28214501Srpaulo * @cipher: Wrapped key, (n + 1) * 64 bits
29214501Srpaulo * Returns: 0 on success, -1 on failure
30214501Srpaulo */
31214501Srpauloint aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
32214501Srpaulo{
33214501Srpaulo	u8 *a, *r, b[16];
34214501Srpaulo	int i, j;
35214501Srpaulo	void *ctx;
36214501Srpaulo
37214501Srpaulo	a = cipher;
38214501Srpaulo	r = cipher + 8;
39214501Srpaulo
40214501Srpaulo	/* 1) Initialize variables. */
41214501Srpaulo	os_memset(a, 0xa6, 8);
42214501Srpaulo	os_memcpy(r, plain, 8 * n);
43214501Srpaulo
44214501Srpaulo	ctx = aes_encrypt_init(kek, 16);
45214501Srpaulo	if (ctx == NULL)
46214501Srpaulo		return -1;
47214501Srpaulo
48214501Srpaulo	/* 2) Calculate intermediate values.
49214501Srpaulo	 * For j = 0 to 5
50214501Srpaulo	 *     For i=1 to n
51214501Srpaulo	 *         B = AES(K, A | R[i])
52214501Srpaulo	 *         A = MSB(64, B) ^ t where t = (n*j)+i
53214501Srpaulo	 *         R[i] = LSB(64, B)
54214501Srpaulo	 */
55214501Srpaulo	for (j = 0; j <= 5; j++) {
56214501Srpaulo		r = cipher + 8;
57214501Srpaulo		for (i = 1; i <= n; i++) {
58214501Srpaulo			os_memcpy(b, a, 8);
59214501Srpaulo			os_memcpy(b + 8, r, 8);
60214501Srpaulo			aes_encrypt(ctx, b, b);
61214501Srpaulo			os_memcpy(a, b, 8);
62214501Srpaulo			a[7] ^= n * j + i;
63214501Srpaulo			os_memcpy(r, b + 8, 8);
64214501Srpaulo			r += 8;
65214501Srpaulo		}
66214501Srpaulo	}
67214501Srpaulo	aes_encrypt_deinit(ctx);
68214501Srpaulo
69214501Srpaulo	/* 3) Output the results.
70214501Srpaulo	 *
71214501Srpaulo	 * These are already in @cipher due to the location of temporary
72214501Srpaulo	 * variables.
73214501Srpaulo	 */
74214501Srpaulo
75214501Srpaulo	return 0;
76214501Srpaulo}
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