1 /*
2 * An implementation of the ARCFOUR algorithm
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 *
7 * This file is provided under the Apache License 2.0, or the
8 * GNU General Public License v2.0 or later.
9 *
10 * **********
11 * Apache License 2.0:
12 *
13 * Licensed under the Apache License, Version 2.0 (the "License"); you may
14 * not use this file except in compliance with the License.
15 * You may obtain a copy of the License at
16 *
17 * http://www.apache.org/licenses/LICENSE-2.0
18 *
19 * Unless required by applicable law or agreed to in writing, software
20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
22 * See the License for the specific language governing permissions and
23 * limitations under the License.
24 *
25 * **********
26 *
27 * **********
28 * GNU General Public License v2.0 or later:
29 *
30 * This program is free software; you can redistribute it and/or modify
31 * it under the terms of the GNU General Public License as published by
32 * the Free Software Foundation; either version 2 of the License, or
33 * (at your option) any later version.
34 *
35 * This program is distributed in the hope that it will be useful,
36 * but WITHOUT ANY WARRANTY; without even the implied warranty of
37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
38 * GNU General Public License for more details.
39 *
40 * You should have received a copy of the GNU General Public License along
41 * with this program; if not, write to the Free Software Foundation, Inc.,
42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
43 *
44 * **********
45 */
46 /*
47 * The ARCFOUR algorithm was publicly disclosed on 94/09.
48 *
49 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
50 */
51
52 #if !defined(MBEDTLS_CONFIG_FILE)
53 #include "mbedtls/config.h"
54 #else
55 #include MBEDTLS_CONFIG_FILE
56 #endif
57
58 #if defined(MBEDTLS_ARC4_C)
59
60 #include "mbedtls/arc4.h"
61 #include "mbedtls/platform_util.h"
62
63 #include <string.h>
64
65 #if defined(MBEDTLS_SELF_TEST)
66 #if defined(MBEDTLS_PLATFORM_C)
67 #include "mbedtls/platform.h"
68 #else
69 #include <stdio.h>
70 #define mbedtls_printf printf
71 #endif /* MBEDTLS_PLATFORM_C */
72 #endif /* MBEDTLS_SELF_TEST */
73
74 #if !defined(MBEDTLS_ARC4_ALT)
75
mbedtls_arc4_init(mbedtls_arc4_context * ctx)76 void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
77 {
78 memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
79 }
80
mbedtls_arc4_free(mbedtls_arc4_context * ctx)81 void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
82 {
83 if( ctx == NULL )
84 return;
85
86 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
87 }
88
89 /*
90 * ARC4 key schedule
91 */
mbedtls_arc4_setup(mbedtls_arc4_context * ctx,const unsigned char * key,unsigned int keylen)92 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
93 unsigned int keylen )
94 {
95 int i, j, a;
96 unsigned int k;
97 unsigned char *m;
98
99 ctx->x = 0;
100 ctx->y = 0;
101 m = ctx->m;
102
103 for( i = 0; i < 256; i++ )
104 m[i] = (unsigned char) i;
105
106 j = k = 0;
107
108 for( i = 0; i < 256; i++, k++ )
109 {
110 if( k >= keylen ) k = 0;
111
112 a = m[i];
113 j = ( j + a + key[k] ) & 0xFF;
114 m[i] = m[j];
115 m[j] = (unsigned char) a;
116 }
117 }
118
119 /*
120 * ARC4 cipher function
121 */
mbedtls_arc4_crypt(mbedtls_arc4_context * ctx,size_t length,const unsigned char * input,unsigned char * output)122 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
123 unsigned char *output )
124 {
125 int x, y, a, b;
126 size_t i;
127 unsigned char *m;
128
129 x = ctx->x;
130 y = ctx->y;
131 m = ctx->m;
132
133 for( i = 0; i < length; i++ )
134 {
135 x = ( x + 1 ) & 0xFF; a = m[x];
136 y = ( y + a ) & 0xFF; b = m[y];
137
138 m[x] = (unsigned char) b;
139 m[y] = (unsigned char) a;
140
141 output[i] = (unsigned char)
142 ( input[i] ^ m[(unsigned char)( a + b )] );
143 }
144
145 ctx->x = x;
146 ctx->y = y;
147
148 return( 0 );
149 }
150
151 #endif /* !MBEDTLS_ARC4_ALT */
152
153 #if defined(MBEDTLS_SELF_TEST)
154 /*
155 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
156 *
157 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
158 */
159 static const unsigned char arc4_test_key[3][8] =
160 {
161 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
162 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
163 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
164 };
165
166 static const unsigned char arc4_test_pt[3][8] =
167 {
168 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
169 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
170 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
171 };
172
173 static const unsigned char arc4_test_ct[3][8] =
174 {
175 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
176 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
177 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
178 };
179
180 /*
181 * Checkup routine
182 */
mbedtls_arc4_self_test(int verbose)183 int mbedtls_arc4_self_test( int verbose )
184 {
185 int i, ret = 0;
186 unsigned char ibuf[8];
187 unsigned char obuf[8];
188 mbedtls_arc4_context ctx;
189
190 mbedtls_arc4_init( &ctx );
191
192 for( i = 0; i < 3; i++ )
193 {
194 if( verbose != 0 )
195 mbedtls_printf( " ARC4 test #%d: ", i + 1 );
196
197 memcpy( ibuf, arc4_test_pt[i], 8 );
198
199 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
200 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );
201
202 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
203 {
204 if( verbose != 0 )
205 mbedtls_printf( "failed\n" );
206
207 ret = 1;
208 goto exit;
209 }
210
211 if( verbose != 0 )
212 mbedtls_printf( "passed\n" );
213 }
214
215 if( verbose != 0 )
216 mbedtls_printf( "\n" );
217
218 exit:
219 mbedtls_arc4_free( &ctx );
220
221 return( ret );
222 }
223
224 #endif /* MBEDTLS_SELF_TEST */
225
226 #endif /* MBEDTLS_ARC4_C */
227