forked from osmocom/wireshark
104 lines
2.6 KiB
C
104 lines
2.6 KiB
C
/*
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Unix SMB/CIFS implementation.
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a partial implementation of RC4 designed for use in the
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SMB authentication protocol
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Copyright (C) Andrew Tridgell 1998
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$Id: crypt-rc4.c,v 1.2 2002/12/11 19:31:02 guy Exp $
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <glib.h>
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#include <string.h>
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#include "crypt-rc4.h"
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/* Perform RC4 on a block of data using specified key. "data" is a pointer
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to the block to be processed. Output is written to same memory as input,
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so caller may need to make a copy before calling this function, since
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the input will be overwritten.
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Taken from Samba source code. Modified to allow us to maintain state
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between calls to crypt_rc4.
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*/
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void crypt_rc4_init(rc4_state_struct *rc4_state,
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const unsigned char *key, int key_len)
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{
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int ind;
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unsigned char j = 0;
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unsigned char *s_box;
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memset(rc4_state, 0, sizeof(rc4_state_struct));
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s_box = rc4_state->s_box;
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for (ind = 0; ind < 256; ind++)
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{
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s_box[ind] = (unsigned char)ind;
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}
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for( ind = 0; ind < 256; ind++)
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{
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unsigned char tc;
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j += (s_box[ind] + key[ind%key_len]);
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tc = s_box[ind];
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s_box[ind] = s_box[j];
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s_box[j] = tc;
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}
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}
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void crypt_rc4(rc4_state_struct *rc4_state, unsigned char *data, int data_len)
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{
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unsigned char *s_box;
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unsigned char index_i;
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unsigned char index_j;
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int ind;
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/* retrieve current state from the state struct (so we can resume where
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we left off) */
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index_i = rc4_state->index_i;
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index_j = rc4_state->index_j;
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s_box = rc4_state->s_box;
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for( ind = 0; ind < data_len; ind++)
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{
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unsigned char tc;
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unsigned char t;
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index_i++;
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index_j += s_box[index_i];
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tc = s_box[index_i];
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s_box[index_i] = s_box[index_j];
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s_box[index_j] = tc;
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t = s_box[index_i] + s_box[index_j];
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data[ind] = data[ind] ^ s_box[t];
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}
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/* Store the updated state */
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rc4_state->index_i = index_i;
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rc4_state->index_j = index_j;
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}
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