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/*
Unix SMB/CIFS implementation.
a partial implementation of RC4 designed for use in the
SMB authentication protocol
Copyright (C) Andrew Tridgell 1998
$Id: crypt-rc4.c,v 1.1 2002/12/03 00:37:27 guy Exp $
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <glib.h>
/* Perform RC4 on a block of data using specified key. "data" is a pointer
to the block to be processed. Output is written to same memory as input,
so caller may need to make a copy before calling this function, since
the input will be overwritten. "val" specifies length of data buffer.
"key" is assumed to be a 16 octets in length
Taken from Samba source code. In the long term, it might be nice to have
the input and output buffer differ, have a length specifier for the key,
and separate the initialization function from the process function (as is
done with the Alleged-RC4 implementation).
*/
void crypt_rc4( unsigned char *data, const unsigned char *key, int val)
{
unsigned char s_box[256];
unsigned char index_i = 0;
unsigned char index_j = 0;
unsigned char j = 0;
int ind;
for (ind = 0; ind < 256; ind++)
{
s_box[ind] = (unsigned char)ind;
}
for( ind = 0; ind < 256; ind++)
{
unsigned char tc;
j += (s_box[ind] + key[ind%16]);
tc = s_box[ind];
s_box[ind] = s_box[j];
s_box[j] = tc;
}
for( ind = 0; ind < val; ind++)
{
unsigned char tc;
unsigned char t;
index_i++;
index_j += s_box[index_i];
tc = s_box[index_i];
s_box[index_i] = s_box[index_j];
s_box[index_j] = tc;
t = s_box[index_i] + s_box[index_j];
data[ind] = data[ind] ^ s_box[t];
}
}
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