aes-wrap.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4 
1/*
2 * AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
3 *
4 * Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
5 *
6 * This software may be distributed under the terms of the BSD license.
7 * See README for more details.
8 */
9
10#include "includes.h"
11
12#include "common.h"
13#include "aes.h"
14#include "aes_wrap.h"
15
16/**
17 * aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
18 * @kek: 16-octet Key encryption key (KEK)
19 * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
20 * bytes
21 * @plain: Plaintext key to be wrapped, n * 64 bits
22 * @cipher: Wrapped key, (n + 1) * 64 bits
23 * Returns: 0 on success, -1 on failure
24 */
25int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
26{
27	u8 *a, *r, b[16];
28	int i, j;
29	void *ctx;
30
31	a = cipher;
32	r = cipher + 8;
33
34	/* 1) Initialize variables. */
35	os_memset(a, 0xa6, 8);
36	os_memcpy(r, plain, 8 * n);
37
38	ctx = aes_encrypt_init(kek, 16);
39	if (ctx == NULL)
40		return -1;
41
42	/* 2) Calculate intermediate values.
43	 * For j = 0 to 5
44	 *     For i=1 to n
45	 *         B = AES(K, A | R[i])
46	 *         A = MSB(64, B) ^ t where t = (n*j)+i
47	 *         R[i] = LSB(64, B)
48	 */
49	for (j = 0; j <= 5; j++) {
50		r = cipher + 8;
51		for (i = 1; i <= n; i++) {
52			os_memcpy(b, a, 8);
53			os_memcpy(b + 8, r, 8);
54			aes_encrypt(ctx, b, b);
55			os_memcpy(a, b, 8);
56			a[7] ^= n * j + i;
57			os_memcpy(r, b + 8, 8);
58			r += 8;
59		}
60	}
61	aes_encrypt_deinit(ctx);
62
63	/* 3) Output the results.
64	 *
65	 * These are already in @cipher due to the location of temporary
66	 * variables.
67	 */
68
69	return 0;
70}
71