PolarSSL v1.2.9
arc4.c
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1 /*
2  * An implementation of the ARCFOUR algorithm
3  *
4  * Copyright (C) 2006-2013, Brainspark B.V.
5  *
6  * This file is part of PolarSSL (http://www.polarssl.org)
7  * Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
8  *
9  * All rights reserved.
10  *
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.
15  *
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.
20  *
21  * You should have received a copy of the GNU General Public License along
22  * with this program; if not, write to the Free Software Foundation, Inc.,
23  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24  */
25 /*
26  * The ARCFOUR algorithm was publicly disclosed on 94/09.
27  *
28  * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
29  */
30 
31 #include "polarssl/config.h"
32 
33 #if defined(POLARSSL_ARC4_C)
34 
35 #include "polarssl/arc4.h"
36 
37 #if !defined(POLARSSL_ARC4_ALT)
38 
39 /*
40  * ARC4 key schedule
41  */
42 void arc4_setup( arc4_context *ctx, const unsigned char *key, unsigned int keylen )
43 {
44  int i, j, a;
45  unsigned int k;
46  unsigned char *m;
47 
48  ctx->x = 0;
49  ctx->y = 0;
50  m = ctx->m;
51 
52  for( i = 0; i < 256; i++ )
53  m[i] = (unsigned char) i;
54 
55  j = k = 0;
56 
57  for( i = 0; i < 256; i++, k++ )
58  {
59  if( k >= keylen ) k = 0;
60 
61  a = m[i];
62  j = ( j + a + key[k] ) & 0xFF;
63  m[i] = m[j];
64  m[j] = (unsigned char) a;
65  }
66 }
67 
68 /*
69  * ARC4 cipher function
70  */
71 int arc4_crypt( arc4_context *ctx, size_t length, const unsigned char *input,
72  unsigned char *output )
73 {
74  int x, y, a, b;
75  size_t i;
76  unsigned char *m;
77 
78  x = ctx->x;
79  y = ctx->y;
80  m = ctx->m;
81 
82  for( i = 0; i < length; i++ )
83  {
84  x = ( x + 1 ) & 0xFF; a = m[x];
85  y = ( y + a ) & 0xFF; b = m[y];
86 
87  m[x] = (unsigned char) b;
88  m[y] = (unsigned char) a;
89 
90  output[i] = (unsigned char)
91  ( input[i] ^ m[(unsigned char)( a + b )] );
92  }
93 
94  ctx->x = x;
95  ctx->y = y;
96 
97  return( 0 );
98 }
99 
100 #endif /* !POLARSSL_ARC4_ALT */
101 
102 #if defined(POLARSSL_SELF_TEST)
103 
104 #include <string.h>
105 #include <stdio.h>
106 
107 /*
108  * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
109  *
110  * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
111  */
112 static const unsigned char arc4_test_key[3][8] =
113 {
114  { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
115  { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
116  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
117 };
118 
119 static const unsigned char arc4_test_pt[3][8] =
120 {
121  { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
122  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
123  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
124 };
125 
126 static const unsigned char arc4_test_ct[3][8] =
127 {
128  { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
129  { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
130  { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
131 };
132 
133 /*
134  * Checkup routine
135  */
136 int arc4_self_test( int verbose )
137 {
138  int i;
139  unsigned char ibuf[8];
140  unsigned char obuf[8];
141  arc4_context ctx;
142 
143  for( i = 0; i < 3; i++ )
144  {
145  if( verbose != 0 )
146  printf( " ARC4 test #%d: ", i + 1 );
147 
148  memcpy( ibuf, arc4_test_pt[i], 8 );
149 
150  arc4_setup( &ctx, arc4_test_key[i], 8 );
151  arc4_crypt( &ctx, 8, ibuf, obuf );
152 
153  if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
154  {
155  if( verbose != 0 )
156  printf( "failed\n" );
157 
158  return( 1 );
159  }
160 
161  if( verbose != 0 )
162  printf( "passed\n" );
163  }
164 
165  if( verbose != 0 )
166  printf( "\n" );
167 
168  return( 0 );
169 }
170 
171 #endif
172 
173 #endif
int arc4_crypt(arc4_context *ctx, size_t length, const unsigned char *input, unsigned char *output)
ARC4 cipher function.
void arc4_setup(arc4_context *ctx, const unsigned char *key, unsigned int keylen)
ARC4 key schedule.
int arc4_self_test(int verbose)
Checkup routine.
Configuration options (set of defines)
int y
Definition: arc4.h:44
unsigned char m[256]
Definition: arc4.h:45
int x
Definition: arc4.h:43
ARC4 context structure.
Definition: arc4.h:41
The ARCFOUR stream cipher.