3 * Copyright (c) 2002-2005, Jouni Malinen <j@w1.fi>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Alternatively, this software may be distributed under the terms of BSD
12 * See README and COPYING for more details.
20 #define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
23 * rc4 - XOR RC4 stream to given data with skip-stream-start
25 * @keylen: RC4 key length
26 * @skip: number of bytes to skip from the beginning of the RC4 stream
27 * @data: data to be XOR'ed with RC4 stream
28 * @data_len: buf length
30 * Generate RC4 pseudo random stream for the given key, skip beginning of the
31 * stream, and XOR the end result with the data buffer to perform RC4
32 * encryption/decryption.
34 void rc4_skip(const u8 *key, size_t keylen, size_t skip,
35 u8 *data, size_t data_len)
42 for (i = 0; i < 256; i++)
46 for (i = 0; i < 256; i++) {
47 j = (j + S[i] + key[kpos]) & 0xff;
54 /* Skip the start of the stream */
56 for (k = 0; k < skip; k++) {
58 j = (j + S[i]) & 0xff;
62 /* Apply RC4 to data */
64 for (k = 0; k < data_len; k++) {
66 j = (j + S[i]) & 0xff;
68 *pos++ ^= S[(S[i] + S[j]) & 0xff];
74 * rc4 - XOR RC4 stream to given data
75 * @buf: data to be XOR'ed with RC4 stream
78 * @key_len: RC4 key length
80 * Generate RC4 pseudo random stream for the given key and XOR this with the
81 * data buffer to perform RC4 encryption/decryption.
83 void rc4(u8 *buf, size_t len, const u8 *key, size_t key_len)
85 rc4_skip(key, key_len, 0, buf, len);