2 Unix SMB/CIFS implementation.
4 a partial implementation of RC4 designed for use in the
5 SMB authentication protocol
7 Copyright (C) Andrew Tridgell 1998
9 $Id: crypt-rc4.c,v 1.2 2002/12/11 19:31:02 guy Exp $
11 This program is free software; you can redistribute it and/or modify
12 it under the terms of the GNU General Public License as published by
13 the Free Software Foundation; either version 2 of the License, or
14 (at your option) any later version.
16 This program is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 GNU General Public License for more details.
21 You should have received a copy of the GNU General Public License
22 along with this program; if not, write to the Free Software
23 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
32 #include "crypt-rc4.h"
34 /* Perform RC4 on a block of data using specified key. "data" is a pointer
35 to the block to be processed. Output is written to same memory as input,
36 so caller may need to make a copy before calling this function, since
37 the input will be overwritten.
39 Taken from Samba source code. Modified to allow us to maintain state
40 between calls to crypt_rc4.
43 void crypt_rc4_init(rc4_state_struct *rc4_state,
44 const unsigned char *key, int key_len)
50 memset(rc4_state, 0, sizeof(rc4_state_struct));
51 s_box = rc4_state->s_box;
53 for (ind = 0; ind < 256; ind++)
55 s_box[ind] = (unsigned char)ind;
58 for( ind = 0; ind < 256; ind++)
62 j += (s_box[ind] + key[ind%key_len]);
65 s_box[ind] = s_box[j];
71 void crypt_rc4(rc4_state_struct *rc4_state, unsigned char *data, int data_len)
74 unsigned char index_i;
75 unsigned char index_j;
78 /* retrieve current state from the state struct (so we can resume where
80 index_i = rc4_state->index_i;
81 index_j = rc4_state->index_j;
82 s_box = rc4_state->s_box;
84 for( ind = 0; ind < data_len; ind++)
90 index_j += s_box[index_i];
93 s_box[index_i] = s_box[index_j];
96 t = s_box[index_i] + s_box[index_j];
97 data[ind] = data[ind] ^ s_box[t];
100 /* Store the updated state */
101 rc4_state->index_i = index_i;
102 rc4_state->index_j = index_j;