1 /*
2 * An implementation of the ARCFOUR algorithm
3 *
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 * This file is part of mbed TLS (https://tls.mbed.org)
20 */
21 /*
22 * The ARCFOUR algorithm was publicly disclosed on 94/09.
23 *
24 * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
25 */
26
27 #if !defined(MBEDTLS_CONFIG_FILE)
28 #include "mbedtls/config.h"
29 #else
30 #include MBEDTLS_CONFIG_FILE
31 #endif
32
33 #if defined(MBEDTLS_ARC4_C)
34
35 #include "mbedtls/arc4.h"
36 #include "mbedtls/platform_util.h"
37
38 #include <string.h>
39
40 #if defined(MBEDTLS_SELF_TEST)
41 #if defined(MBEDTLS_PLATFORM_C)
42 #include "mbedtls/platform.h"
43 #else
44 #include <stdio.h>
45 #define mbedtls_printf printf
46 #endif /* MBEDTLS_PLATFORM_C */
47 #endif /* MBEDTLS_SELF_TEST */
48
49 #if !defined(MBEDTLS_ARC4_ALT)
50
mbedtls_arc4_init(mbedtls_arc4_context * ctx)51 void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
52 {
53 memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
54 }
55
mbedtls_arc4_free(mbedtls_arc4_context * ctx)56 void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
57 {
58 if( ctx == NULL )
59 return;
60
61 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
62 }
63
64 /*
65 * ARC4 key schedule
66 */
mbedtls_arc4_setup(mbedtls_arc4_context * ctx,const unsigned char * key,unsigned int keylen)67 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
68 unsigned int keylen )
69 {
70 int i, j, a;
71 unsigned int k;
72 unsigned char *m;
73
74 ctx->x = 0;
75 ctx->y = 0;
76 m = ctx->m;
77
78 for( i = 0; i < 256; i++ )
79 m[i] = (unsigned char) i;
80
81 j = k = 0;
82
83 for( i = 0; i < 256; i++, k++ )
84 {
85 if( k >= keylen ) k = 0;
86
87 a = m[i];
88 j = ( j + a + key[k] ) & 0xFF;
89 m[i] = m[j];
90 m[j] = (unsigned char) a;
91 }
92 }
93
94 /*
95 * ARC4 cipher function
96 */
mbedtls_arc4_crypt(mbedtls_arc4_context * ctx,size_t length,const unsigned char * input,unsigned char * output)97 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
98 unsigned char *output )
99 {
100 int x, y, a, b;
101 size_t i;
102 unsigned char *m;
103
104 x = ctx->x;
105 y = ctx->y;
106 m = ctx->m;
107
108 for( i = 0; i < length; i++ )
109 {
110 x = ( x + 1 ) & 0xFF; a = m[x];
111 y = ( y + a ) & 0xFF; b = m[y];
112
113 m[x] = (unsigned char) b;
114 m[y] = (unsigned char) a;
115
116 output[i] = (unsigned char)
117 ( input[i] ^ m[(unsigned char)( a + b )] );
118 }
119
120 ctx->x = x;
121 ctx->y = y;
122
123 return( 0 );
124 }
125
126 #endif /* !MBEDTLS_ARC4_ALT */
127
128 #if defined(MBEDTLS_SELF_TEST)
129 /*
130 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
131 *
132 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
133 */
134 static const unsigned char arc4_test_key[3][8] =
135 {
136 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
137 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
138 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
139 };
140
141 static const unsigned char arc4_test_pt[3][8] =
142 {
143 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
144 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
145 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
146 };
147
148 static const unsigned char arc4_test_ct[3][8] =
149 {
150 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
151 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
152 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
153 };
154
155 /*
156 * Checkup routine
157 */
mbedtls_arc4_self_test(int verbose)158 int mbedtls_arc4_self_test( int verbose )
159 {
160 int i, ret = 0;
161 unsigned char ibuf[8];
162 unsigned char obuf[8];
163 mbedtls_arc4_context ctx;
164
165 mbedtls_arc4_init( &ctx );
166
167 for( i = 0; i < 3; i++ )
168 {
169 if( verbose != 0 )
170 mbedtls_printf( " ARC4 test #%d: ", i + 1 );
171
172 memcpy( ibuf, arc4_test_pt[i], 8 );
173
174 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
175 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );
176
177 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
178 {
179 if( verbose != 0 )
180 mbedtls_printf( "failed\n" );
181
182 ret = 1;
183 goto exit;
184 }
185
186 if( verbose != 0 )
187 mbedtls_printf( "passed\n" );
188 }
189
190 if( verbose != 0 )
191 mbedtls_printf( "\n" );
192
193 exit:
194 mbedtls_arc4_free( &ctx );
195
196 return( ret );
197 }
198
199 #endif /* MBEDTLS_SELF_TEST */
200
201 #endif /* MBEDTLS_ARC4_C */
202