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/*
* Copyright 2006 Mike McCormack
*
* based on arc4.cpp - written and placed in the public domain by Wei Dai
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
/* http://cryptopp.sourceforge.net/docs/ref521/arc4_8cpp-source.html */
#include <stdarg.h>
#include "ntstatus.h"
#define WIN32_NO_STATUS
#include "windef.h"
#include "winternl.h"
#include "crypt.h"
typedef struct tag_arc4_info {
unsigned char state[256];
unsigned char x, y;
} arc4_info;
static void arc4_init(arc4_info *a4i, const BYTE *key, unsigned int keyLen)
{
unsigned int keyIndex = 0, stateIndex = 0;
unsigned int i, a;
a4i->x = a4i->y = 0;
for (i=0; i<256; i++)
a4i->state[i] = i;
for (i=0; i<256; i++)
{
a = a4i->state[i];
stateIndex += key[keyIndex] + a;
stateIndex &= 0xff;
a4i->state[i] = a4i->state[stateIndex];
a4i->state[stateIndex] = a;
if (++keyIndex >= keyLen)
keyIndex = 0;
}
}
static void arc4_ProcessString(arc4_info *a4i, BYTE *inoutString, unsigned int length)
{
BYTE *const s=a4i->state;
unsigned int x = a4i->x;
unsigned int y = a4i->y;
unsigned int a, b;
while(length--)
{
x = (x+1) & 0xff;
a = s[x];
y = (y+a) & 0xff;
b = s[y];
s[x] = b;
s[y] = a;
*inoutString++ ^= s[(a+b) & 0xff];
}
a4i->x = x;
a4i->y = y;
}
/******************************************************************************
* SystemFunction032 [ADVAPI32.@]
*
* Encrypts a string data using ARC4
*
* PARAMS
* data [I/O] data to encrypt
* key [I] key data
*
* RETURNS
* Success: STATUS_SUCCESS
* Failure: STATUS_UNSUCCESSFUL
*
* NOTES
* see http://web.it.kth.se/~rom/ntsec.html#crypto-strongavail
*/
NTSTATUS WINAPI SystemFunction032(struct ustring *data, const struct ustring *key)
{
arc4_info a4i;
arc4_init(&a4i, key->Buffer, key->Length);
arc4_ProcessString(&a4i, data->Buffer, data->Length);
return STATUS_SUCCESS;
}
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