1/*
2 * AES Key Wrap Algorithm (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 (RFC3394)
18 * @kek: Key encryption key (KEK)
19 * @kek_len: Length of KEK in octets
20 * @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
21 * bytes
22 * @plain: Plaintext key to be wrapped, n * 64 bits
23 * @cipher: Wrapped key, (n + 1) * 64 bits
24 * Returns: 0 on success, -1 on failure
25 */
26int aes_wrap(const u8 *kek, size_t kek_len, int n, const u8 *plain, u8 *cipher)
27{
28	u8 *a, *r, b[AES_BLOCK_SIZE];
29	int i, j;
30	void *ctx;
31	unsigned int t;
32
33	a = cipher;
34	r = cipher + 8;
35
36	/* 1) Initialize variables. */
37	os_memset(a, 0xa6, 8);
38	os_memcpy(r, plain, 8 * n);
39
40	ctx = aes_encrypt_init(kek, kek_len);
41	if (ctx == NULL)
42		return -1;
43
44	/* 2) Calculate intermediate values.
45	 * For j = 0 to 5
46	 *     For i=1 to n
47	 *         B = AES(K, A | R[i])
48	 *         A = MSB(64, B) ^ t where t = (n*j)+i
49	 *         R[i] = LSB(64, B)
50	 */
51	for (j = 0; j <= 5; j++) {
52		r = cipher + 8;
53		for (i = 1; i <= n; i++) {
54			os_memcpy(b, a, 8);
55			os_memcpy(b + 8, r, 8);
56			aes_encrypt(ctx, b, b);
57			os_memcpy(a, b, 8);
58			t = n * j + i;
59			a[7] ^= t;
60			a[6] ^= t >> 8;
61			a[5] ^= t >> 16;
62			a[4] ^= t >> 24;
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}
77