| 1 | /*
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| 2 | * Copyright 2006 Mike McCormack
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| 3 | *
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| 4 | * based on arc4.cpp - written and placed in the public domain by Wei Dai
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| 5 | *
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| 6 | * This library is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU Lesser General Public
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| 8 | * License as published by the Free Software Foundation; either
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| 9 | * version 2.1 of the License, or (at your option) any later version.
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| 10 | *
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| 11 | * This library is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 14 | * Lesser General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU Lesser General Public
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| 17 | * License along with this library; if not, write to the Free Software
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| 18 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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| 19 | */
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| 20 |
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| 21 | /* http://cryptopp.sourceforge.net/docs/ref521/arc4_8cpp-source.html */
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| 22 |
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| 23 | #include <stdarg.h>
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| 24 |
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| 25 | #include "ntstatus.h"
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| 26 | #define WIN32_NO_STATUS
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| 27 | #include "windef.h"
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| 28 | #include "winternl.h"
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| 29 |
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| 30 | #include "crypt.h"
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| 31 |
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| 32 | typedef struct tag_arc4_info {
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| 33 | unsigned char state[256];
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| 34 | unsigned char x, y;
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| 35 | } arc4_info;
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| 36 |
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| 37 | static void arc4_init(arc4_info *a4i, const BYTE *key, unsigned int keyLen)
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| 38 | {
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| 39 | unsigned int keyIndex = 0, stateIndex = 0;
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| 40 | unsigned int i, a;
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| 41 |
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| 42 | a4i->x = a4i->y = 0;
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| 43 |
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| 44 | for (i=0; i<256; i++)
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| 45 | a4i->state[i] = i;
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| 46 |
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| 47 | for (i=0; i<256; i++)
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| 48 | {
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| 49 | a = a4i->state[i];
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| 50 | stateIndex += key[keyIndex] + a;
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| 51 | stateIndex &= 0xff;
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| 52 | a4i->state[i] = a4i->state[stateIndex];
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| 53 | a4i->state[stateIndex] = a;
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| 54 | if (++keyIndex >= keyLen)
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| 55 | keyIndex = 0;
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| 56 | }
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| 57 | }
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| 58 |
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| 59 | static void arc4_ProcessString(arc4_info *a4i, BYTE *inoutString, unsigned int length)
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| 60 | {
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| 61 | BYTE *const s=a4i->state;
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| 62 | unsigned int x = a4i->x;
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| 63 | unsigned int y = a4i->y;
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| 64 | unsigned int a, b;
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| 65 |
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| 66 | while(length--)
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| 67 | {
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| 68 | x = (x+1) & 0xff;
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| 69 | a = s[x];
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| 70 | y = (y+a) & 0xff;
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| 71 | b = s[y];
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| 72 | s[x] = b;
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| 73 | s[y] = a;
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| 74 | *inoutString++ ^= s[(a+b) & 0xff];
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| 75 | }
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| 76 |
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| 77 | a4i->x = x;
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| 78 | a4i->y = y;
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| 79 | }
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| 80 |
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| 81 | /******************************************************************************
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| 82 | * SystemFunction032 [ADVAPI32.@]
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| 83 | *
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| 84 | * Encrypts a string data using ARC4
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| 85 | *
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| 86 | * PARAMS
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| 87 | * data [I/O] data to encrypt
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| 88 | * key [I] key data
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| 89 | *
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| 90 | * RETURNS
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| 91 | * Success: STATUS_SUCCESS
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| 92 | * Failure: STATUS_UNSUCCESSFUL
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| 93 | *
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| 94 | * NOTES
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| 95 | * see http://web.it.kth.se/~rom/ntsec.html#crypto-strongavail
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| 96 | */
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| 97 | NTSTATUS WINAPI SystemFunction032(struct ustring *data, struct ustring *key)
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| 98 | {
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| 99 | arc4_info a4i;
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| 100 |
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| 101 | arc4_init(&a4i, key->Buffer, key->Length);
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| 102 | arc4_ProcessString(&a4i, data->Buffer, data->Length);
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| 103 |
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| 104 | return STATUS_SUCCESS;
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| 105 | }
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