| 1 | /*
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| 2 | Unix SMB/CIFS implementation.
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| 3 |
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| 4 | An implementation of arc4.
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| 5 |
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| 6 | Copyright (C) Jeremy Allison 2005.
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| 7 |
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| 8 | This program is free software; you can redistribute it and/or modify
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| 9 | it under the terms of the GNU General Public License as published by
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| 10 | the Free Software Foundation; either version 2 of the License, or
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| 11 | (at your option) any later version.
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| 12 |
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| 13 | This program is distributed in the hope that it will be useful,
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| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | GNU General Public License for more details.
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| 17 |
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| 18 | You should have received a copy of the GNU General Public License
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| 19 | along with this program; if not, write to the Free Software
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| 20 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 21 | */
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| 22 |
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| 23 | #include "includes.h"
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| 24 |
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| 25 | /*****************************************************************
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| 26 | Initialize state for an arc4 crypt/decrpyt.
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| 27 | arc4 state is 258 bytes - last 2 bytes are the index bytes.
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| 28 | *****************************************************************/
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| 29 |
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| 30 | void smb_arc4_init(unsigned char arc4_state_out[258], const unsigned char *key, size_t keylen)
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| 31 | {
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| 32 | size_t ind;
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| 33 | unsigned char j = 0;
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| 34 |
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| 35 | for (ind = 0; ind < 256; ind++) {
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| 36 | arc4_state_out[ind] = (unsigned char)ind;
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| 37 | }
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| 38 |
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| 39 | for( ind = 0; ind < 256; ind++) {
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| 40 | unsigned char tc;
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| 41 |
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| 42 | j += (arc4_state_out[ind] + key[ind%keylen]);
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| 43 |
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| 44 | tc = arc4_state_out[ind];
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| 45 | arc4_state_out[ind] = arc4_state_out[j];
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| 46 | arc4_state_out[j] = tc;
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| 47 | }
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| 48 | arc4_state_out[256] = 0;
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| 49 | arc4_state_out[257] = 0;
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| 50 | }
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| 51 |
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| 52 | /*****************************************************************
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| 53 | Do the arc4 crypt/decrpyt.
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| 54 | arc4 state is 258 bytes - last 2 bytes are the index bytes.
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| 55 | *****************************************************************/
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| 56 |
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| 57 | void smb_arc4_crypt(unsigned char arc4_state_inout[258], unsigned char *data, size_t len)
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| 58 | {
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| 59 | unsigned char index_i = arc4_state_inout[256];
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| 60 | unsigned char index_j = arc4_state_inout[257];
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| 61 | size_t ind;
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| 62 |
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| 63 | for( ind = 0; ind < len; ind++) {
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| 64 | unsigned char tc;
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| 65 | unsigned char t;
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| 66 |
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| 67 | index_i++;
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| 68 | index_j += arc4_state_inout[index_i];
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| 69 |
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| 70 | tc = arc4_state_inout[index_i];
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| 71 | arc4_state_inout[index_i] = arc4_state_inout[index_j];
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| 72 | arc4_state_inout[index_j] = tc;
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| 73 |
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| 74 | t = arc4_state_inout[index_i] + arc4_state_inout[index_j];
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| 75 | data[ind] = data[ind] ^ arc4_state_inout[t];
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| 76 | }
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| 77 |
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| 78 | arc4_state_inout[256] = index_i;
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| 79 | arc4_state_inout[257] = index_j;
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| 80 | }
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