1 | /*
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2 | * An implementation of the ARCFOUR algorithm
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3 | *
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4 | * Based on XySSL: Copyright (C) 2006-2008 Christophe Devine
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5 | *
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6 | * Copyright (C) 2009 Paul Bakker <polarssl_maintainer at polarssl dot org>
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7 | *
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8 | * All rights reserved.
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9 | *
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10 | * Redistribution and use in source and binary forms, with or without
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11 | * modification, are permitted provided that the following conditions
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12 | * are met:
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13 | *
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14 | * * Redistributions of source code must retain the above copyright
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15 | * notice, this list of conditions and the following disclaimer.
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16 | * * Redistributions in binary form must reproduce the above copyright
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17 | * notice, this list of conditions and the following disclaimer in the
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18 | * documentation and/or other materials provided with the distribution.
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19 | * * Neither the names of PolarSSL or XySSL nor the names of its contributors
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20 | * may be used to endorse or promote products derived from this software
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21 | * without specific prior written permission.
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22 | *
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23 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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24 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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25 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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26 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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27 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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28 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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29 | * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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30 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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31 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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32 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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33 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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34 | */
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35 | /*
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36 | * The ARCFOUR algorithm was publicly disclosed on 94/09.
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37 | *
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38 | * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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39 | */
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40 |
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41 | #include "netif/ppp/ppp_opts.h"
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42 | #if PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_ARC4
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43 |
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44 | #include "netif/ppp/polarssl/arc4.h"
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45 | /*
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46 | * ARC4 key schedule
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47 | */
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48 | void arc4_setup( arc4_context *ctx, unsigned char *key, int keylen )
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49 | {
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50 | int i, j, k, a;
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51 | unsigned char *m;
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52 |
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53 | ctx->x = 0;
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54 | ctx->y = 0;
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55 | m = ctx->m;
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56 |
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57 | for( i = 0; i < 256; i++ )
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58 | m[i] = (unsigned char) i;
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59 |
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60 | j = k = 0;
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61 |
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62 | for( i = 0; i < 256; i++, k++ )
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63 | {
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64 | if( k >= keylen ) k = 0;
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65 |
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66 | a = m[i];
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67 | j = ( j + a + key[k] ) & 0xFF;
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68 | m[i] = m[j];
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69 | m[j] = (unsigned char) a;
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70 | }
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71 | }
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72 |
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73 | /*
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74 | * ARC4 cipher function
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75 | */
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76 | void arc4_crypt( arc4_context *ctx, unsigned char *buf, int buflen )
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77 | {
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78 | int i, x, y, a, b;
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79 | unsigned char *m;
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80 |
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81 | x = ctx->x;
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82 | y = ctx->y;
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83 | m = ctx->m;
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84 |
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85 | for( i = 0; i < buflen; i++ )
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86 | {
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87 | x = ( x + 1 ) & 0xFF; a = m[x];
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88 | y = ( y + a ) & 0xFF; b = m[y];
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89 |
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90 | m[x] = (unsigned char) b;
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91 | m[y] = (unsigned char) a;
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92 |
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93 | buf[i] = (unsigned char)
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94 | ( buf[i] ^ m[(unsigned char)( a + b )] );
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95 | }
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96 |
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97 | ctx->x = x;
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98 | ctx->y = y;
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99 | }
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100 |
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101 | #endif /* PPP_SUPPORT && LWIP_INCLUDED_POLARSSL_DES */
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