1 /*
2 * Copyright 2006 Mike McCormack
3 *
4 * based on arc4.cpp - written and placed in the public domain by Wei Dai
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
19 */
20
21 /* http://cryptopp.sourceforge.net/docs/ref521/arc4_8cpp-source.html */
22
23 #include <stdarg.h>
24
25 #include "ntstatus.h"
26 #define WIN32_NO_STATUS
27 #include "windef.h"
28 #include "winternl.h"
29
30 #include "crypt.h"
31
32 typedef struct tag_arc4_info {
33 unsigned char state[256];
34 unsigned char x, y;
35 } arc4_info;
36
37 static void arc4_init(arc4_info *a4i, const BYTE *key, unsigned int keyLen)
38 {
39 unsigned int keyIndex = 0, stateIndex = 0;
40 unsigned int i, a;
41
42 a4i->x = a4i->y = 0;
43
44 for (i=0; i<256; i++)
45 a4i->state[i] = i;
46
47 for (i=0; i<256; i++)
48 {
49 a = a4i->state[i];
50 stateIndex += key[keyIndex] + a;
51 stateIndex &= 0xff;
52 a4i->state[i] = a4i->state[stateIndex];
53 a4i->state[stateIndex] = a;
54 if (++keyIndex >= keyLen)
55 keyIndex = 0;
56 }
57 }
58
59 static void arc4_ProcessString(arc4_info *a4i, BYTE *inoutString, unsigned int length)
60 {
61 BYTE *const s=a4i->state;
62 unsigned int x = a4i->x;
63 unsigned int y = a4i->y;
64 unsigned int a, b;
65
66 while(length--)
67 {
68 x = (x+1) & 0xff;
69 a = s[x];
70 y = (y+a) & 0xff;
71 b = s[y];
72 s[x] = b;
73 s[y] = a;
74 *inoutString++ ^= s[(a+b) & 0xff];
75 }
76
77 a4i->x = x;
78 a4i->y = y;
79 }
80
81 /******************************************************************************
82 * SystemFunction032 [ADVAPI32.@]
83 *
84 * Encrypts a string data using ARC4
85 *
86 * PARAMS
87 * data [I/O] data to encrypt
88 * key [I] key data
89 *
90 * RETURNS
91 * Success: STATUS_SUCCESS
92 * Failure: STATUS_UNSUCCESSFUL
93 *
94 * NOTES
95 * see http://web.it.kth.se/~rom/ntsec.html#crypto-strongavail
96 */
97 NTSTATUS WINAPI SystemFunction032(struct ustring *data, struct ustring *key)
98 {
99 arc4_info a4i;
100
101 arc4_init(&a4i, key->Buffer, key->Length);
102 arc4_ProcessString(&a4i, data->Buffer, data->Length);
103
104 return STATUS_SUCCESS;
105 }
106
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