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/drivers/staging/vt6656/rc4.c

https://bitbucket.org/wisechild/galaxy-nexus
C | 87 lines | 49 code | 7 blank | 31 comment | 4 complexity | 1bf51d27c54cb203067b7e3d498b5bc0 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
 1/*
 2 * Copyright (c) 1996, 2003 VIA Networking Technologies, Inc.
 3 * All rights reserved.
 4 *
 5 * This program is free software; you can redistribute it and/or modify
 6 * it under the terms of the GNU General Public License as published by
 7 * the Free Software Foundation; either version 2 of the License, or
 8 * (at your option) any later version.
 9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * File: rc4.c
20 *
21 * Purpose:
22 *
23 * Functions:
24 *
25 * Revision History:
26 *
27 * Author: Kyle Hsu
28 *
29 * Date: Sep 4, 2002
30 *
31 */
32
33#include "rc4.h"
34
35void rc4_init(PRC4Ext pRC4, PBYTE pbyKey, unsigned int cbKey_len)
36{
37	unsigned int  ust1, ust2;
38	unsigned int  keyindex;
39	unsigned int  stateindex;
40	PBYTE pbyst;
41	unsigned int  idx;
42
43	pbyst = pRC4->abystate;
44	pRC4->ux = 0;
45	pRC4->uy = 0;
46	for (idx = 0; idx < 256; idx++)
47		pbyst[idx] = (BYTE)idx;
48	keyindex = 0;
49	stateindex = 0;
50	for (idx = 0; idx < 256; idx++) {
51		ust1 = pbyst[idx];
52		stateindex = (stateindex + pbyKey[keyindex] + ust1) & 0xff;
53		ust2 = pbyst[stateindex];
54		pbyst[stateindex] = (BYTE)ust1;
55		pbyst[idx] = (BYTE)ust2;
56		if (++keyindex >= cbKey_len)
57			keyindex = 0;
58	}
59}
60
61unsigned int rc4_byte(PRC4Ext pRC4)
62{
63	unsigned int ux;
64	unsigned int uy;
65	unsigned int ustx, usty;
66	PBYTE pbyst;
67
68	pbyst = pRC4->abystate;
69	ux = (pRC4->ux + 1) & 0xff;
70	ustx = pbyst[ux];
71	uy = (ustx + pRC4->uy) & 0xff;
72	usty = pbyst[uy];
73	pRC4->ux = ux;
74	pRC4->uy = uy;
75	pbyst[uy] = (BYTE)ustx;
76	pbyst[ux] = (BYTE)usty;
77
78	return pbyst[(ustx + usty) & 0xff];
79}
80
81void rc4_encrypt(PRC4Ext pRC4, PBYTE pbyDest,
82			PBYTE pbySrc, unsigned int cbData_len)
83{
84	unsigned int ii;
85	for (ii = 0; ii < cbData_len; ii++)
86		pbyDest[ii] = (BYTE)(pbySrc[ii] ^ rc4_byte(pRC4));
87}