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
37 #include <string.h>
38
39 #if defined(MBEDTLS_SELF_TEST)
40 #if defined(MBEDTLS_PLATFORM_C)
41 #include "mbedtls/platform.h"
42 #else
43 #include <stdio.h>
44 #define mbedtls_printf printf
45 #endif /* MBEDTLS_PLATFORM_C */
46 #endif /* MBEDTLS_SELF_TEST */
47
48 #if !defined(MBEDTLS_ARC4_ALT)
49
50 /* Implementation that should never be optimized out by the compiler */
mbedtls_zeroize(void * v,size_t n)51 static void mbedtls_zeroize( void *v, size_t n ) {
52 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
53 }
54
mbedtls_arc4_init(mbedtls_arc4_context * ctx)55 void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
56 {
57 memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
58 }
59
mbedtls_arc4_free(mbedtls_arc4_context * ctx)60 void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
61 {
62 if( ctx == NULL )
63 return;
64
65 mbedtls_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
66 }
67
68 /*
69 * ARC4 key schedule
70 */
mbedtls_arc4_setup(mbedtls_arc4_context * ctx,const unsigned char * key,unsigned int keylen)71 void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
72 unsigned int keylen )
73 {
74 int i, j, a;
75 unsigned int k;
76 unsigned char *m;
77
78 ctx->x = 0;
79 ctx->y = 0;
80 m = ctx->m;
81
82 for( i = 0; i < 256; i++ )
83 m[i] = (unsigned char) i;
84
85 j = k = 0;
86
87 for( i = 0; i < 256; i++, k++ )
88 {
89 if( k >= keylen ) k = 0;
90
91 a = m[i];
92 j = ( j + a + key[k] ) & 0xFF;
93 m[i] = m[j];
94 m[j] = (unsigned char) a;
95 }
96 }
97
98 /*
99 * ARC4 cipher function
100 */
mbedtls_arc4_crypt(mbedtls_arc4_context * ctx,size_t length,const unsigned char * input,unsigned char * output)101 int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
102 unsigned char *output )
103 {
104 int x, y, a, b;
105 size_t i;
106 unsigned char *m;
107
108 x = ctx->x;
109 y = ctx->y;
110 m = ctx->m;
111
112 for( i = 0; i < length; i++ )
113 {
114 x = ( x + 1 ) & 0xFF; a = m[x];
115 y = ( y + a ) & 0xFF; b = m[y];
116
117 m[x] = (unsigned char) b;
118 m[y] = (unsigned char) a;
119
120 output[i] = (unsigned char)
121 ( input[i] ^ m[(unsigned char)( a + b )] );
122 }
123
124 ctx->x = x;
125 ctx->y = y;
126
127 return( 0 );
128 }
129
130 #endif /* !MBEDTLS_ARC4_ALT */
131
132 #if defined(MBEDTLS_SELF_TEST)
133 /*
134 * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
135 *
136 * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
137 */
138 static const unsigned char arc4_test_key[3][8] =
139 {
140 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
141 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
142 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
143 };
144
145 static const unsigned char arc4_test_pt[3][8] =
146 {
147 { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
148 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
149 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
150 };
151
152 static const unsigned char arc4_test_ct[3][8] =
153 {
154 { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
155 { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
156 { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
157 };
158
159 /*
160 * Checkup routine
161 */
mbedtls_arc4_self_test(int verbose)162 int mbedtls_arc4_self_test( int verbose )
163 {
164 int i, ret = 0;
165 unsigned char ibuf[8];
166 unsigned char obuf[8];
167 mbedtls_arc4_context ctx;
168
169 mbedtls_arc4_init( &ctx );
170
171 for( i = 0; i < 3; i++ )
172 {
173 if( verbose != 0 )
174 mbedtls_printf( " ARC4 test #%d: ", i + 1 );
175
176 memcpy( ibuf, arc4_test_pt[i], 8 );
177
178 mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
179 mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );
180
181 if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
182 {
183 if( verbose != 0 )
184 mbedtls_printf( "failed\n" );
185
186 ret = 1;
187 goto exit;
188 }
189
190 if( verbose != 0 )
191 mbedtls_printf( "passed\n" );
192 }
193
194 if( verbose != 0 )
195 mbedtls_printf( "\n" );
196
197 exit:
198 mbedtls_arc4_free( &ctx );
199
200 return( ret );
201 }
202
203 #endif /* MBEDTLS_SELF_TEST */
204
205 #endif /* MBEDTLS_ARC4_C */
206
