aes-cbc.c revision 8d520ff1dc2da35cdca849e982051b86468016d8 
1/*
2 * AES-128 CBC
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_128_cbc_encrypt - AES-128 CBC encryption
24 * @key: Encryption key
25 * @iv: Encryption IV for CBC mode (16 bytes)
26 * @data: Data to encrypt in-place
27 * @data_len: Length of data in bytes (must be divisible by 16)
28 * Returns: 0 on success, -1 on failure
29 */
30int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
31{
32	void *ctx;
33	u8 cbc[AES_BLOCK_SIZE];
34	u8 *pos = data;
35	int i, j, blocks;
36
37	ctx = aes_encrypt_init(key, 16);
38	if (ctx == NULL)
39		return -1;
40	os_memcpy(cbc, iv, AES_BLOCK_SIZE);
41
42	blocks = data_len / AES_BLOCK_SIZE;
43	for (i = 0; i < blocks; i++) {
44		for (j = 0; j < AES_BLOCK_SIZE; j++)
45			cbc[j] ^= pos[j];
46		aes_encrypt(ctx, cbc, cbc);
47		os_memcpy(pos, cbc, AES_BLOCK_SIZE);
48		pos += AES_BLOCK_SIZE;
49	}
50	aes_encrypt_deinit(ctx);
51	return 0;
52}
53
54
55/**
56 * aes_128_cbc_decrypt - AES-128 CBC decryption
57 * @key: Decryption key
58 * @iv: Decryption IV for CBC mode (16 bytes)
59 * @data: Data to decrypt in-place
60 * @data_len: Length of data in bytes (must be divisible by 16)
61 * Returns: 0 on success, -1 on failure
62 */
63int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
64{
65	void *ctx;
66	u8 cbc[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE];
67	u8 *pos = data;
68	int i, j, blocks;
69
70	ctx = aes_decrypt_init(key, 16);
71	if (ctx == NULL)
72		return -1;
73	os_memcpy(cbc, iv, AES_BLOCK_SIZE);
74
75	blocks = data_len / AES_BLOCK_SIZE;
76	for (i = 0; i < blocks; i++) {
77		os_memcpy(tmp, pos, AES_BLOCK_SIZE);
78		aes_decrypt(ctx, pos, pos);
79		for (j = 0; j < AES_BLOCK_SIZE; j++)
80			pos[j] ^= cbc[j];
81		os_memcpy(cbc, tmp, AES_BLOCK_SIZE);
82		pos += AES_BLOCK_SIZE;
83	}
84	aes_decrypt_deinit(ctx);
85	return 0;
86}
87