| 1 | /* |
| 2 | * An implementation of the ARCFOUR algorithm |
| 3 | * |
| 4 | * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved |
| 5 | * SPDX-License-Identifier: GPL-2.0 |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License along |
| 18 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 19 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * This file is part of mbed TLS (https://tls.mbed.org) |
| 22 | */ |
| 23 | /* |
| 24 | * The ARCFOUR algorithm was publicly disclosed on 94/09. |
| 25 | * |
| 26 | * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 |
| 27 | */ |
| 28 | |
| 29 | #if !defined(MBEDTLS_CONFIG_FILE) |
| 30 | #include "mbedtls/config.h" |
| 31 | #else |
| 32 | #include MBEDTLS_CONFIG_FILE |
| 33 | #endif |
| 34 | |
| 35 | #if defined(MBEDTLS_ARC4_C) |
| 36 | |
| 37 | #include "mbedtls/arc4.h" |
| 38 | #include "mbedtls/platform_util.h" |
| 39 | |
| 40 | #include <string.h> |
| 41 | |
| 42 | #if defined(MBEDTLS_SELF_TEST) |
| 43 | #if defined(MBEDTLS_PLATFORM_C) |
| 44 | #include "mbedtls/platform.h" |
| 45 | #else |
| 46 | #include <stdio.h> |
| 47 | #define mbedtls_printf printf |
| 48 | #endif /* MBEDTLS_PLATFORM_C */ |
| 49 | #endif /* MBEDTLS_SELF_TEST */ |
| 50 | |
| 51 | #if !defined(MBEDTLS_ARC4_ALT) |
| 52 | |
| 53 | void mbedtls_arc4_init( mbedtls_arc4_context *ctx ) |
| 54 | { |
| 55 | memset( ctx, 0, sizeof( mbedtls_arc4_context ) ); |
| 56 | } |
| 57 | |
| 58 | void mbedtls_arc4_free( mbedtls_arc4_context *ctx ) |
| 59 | { |
| 60 | if( ctx == NULL ) |
| 61 | return; |
| 62 | |
| 63 | mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) ); |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * ARC4 key schedule |
| 68 | */ |
| 69 | void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key, |
| 70 | unsigned int keylen ) |
| 71 | { |
| 72 | int i, j, a; |
| 73 | unsigned int k; |
| 74 | unsigned char *m; |
| 75 | |
| 76 | ctx->x = 0; |
| 77 | ctx->y = 0; |
| 78 | m = ctx->m; |
| 79 | |
| 80 | for( i = 0; i < 256; i++ ) |
| 81 | m[i] = (unsigned char) i; |
| 82 | |
| 83 | j = k = 0; |
| 84 | |
| 85 | for( i = 0; i < 256; i++, k++ ) |
| 86 | { |
| 87 | if( k >= keylen ) k = 0; |
| 88 | |
| 89 | a = m[i]; |
| 90 | j = ( j + a + key[k] ) & 0xFF; |
| 91 | m[i] = m[j]; |
| 92 | m[j] = (unsigned char) a; |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * ARC4 cipher function |
| 98 | */ |
| 99 | int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input, |
| 100 | unsigned char *output ) |
| 101 | { |
| 102 | int x, y, a, b; |
| 103 | size_t i; |
| 104 | unsigned char *m; |
| 105 | |
| 106 | x = ctx->x; |
| 107 | y = ctx->y; |
| 108 | m = ctx->m; |
| 109 | |
| 110 | for( i = 0; i < length; i++ ) |
| 111 | { |
| 112 | x = ( x + 1 ) & 0xFF; a = m[x]; |
| 113 | y = ( y + a ) & 0xFF; b = m[y]; |
| 114 | |
| 115 | m[x] = (unsigned char) b; |
| 116 | m[y] = (unsigned char) a; |
| 117 | |
| 118 | output[i] = (unsigned char) |
| 119 | ( input[i] ^ m[(unsigned char)( a + b )] ); |
| 120 | } |
| 121 | |
| 122 | ctx->x = x; |
| 123 | ctx->y = y; |
| 124 | |
| 125 | return( 0 ); |
| 126 | } |
| 127 | |
| 128 | #endif /* !MBEDTLS_ARC4_ALT */ |
| 129 | |
| 130 | #if defined(MBEDTLS_SELF_TEST) |
| 131 | /* |
| 132 | * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: |
| 133 | * |
| 134 | * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 |
| 135 | */ |
| 136 | static const unsigned char arc4_test_key[3][8] = |
| 137 | { |
| 138 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
| 139 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
| 140 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } |
| 141 | }; |
| 142 | |
| 143 | static const unsigned char arc4_test_pt[3][8] = |
| 144 | { |
| 145 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
| 146 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, |
| 147 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } |
| 148 | }; |
| 149 | |
| 150 | static const unsigned char arc4_test_ct[3][8] = |
| 151 | { |
| 152 | { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, |
| 153 | { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, |
| 154 | { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } |
| 155 | }; |
| 156 | |
| 157 | /* |
| 158 | * Checkup routine |
| 159 | */ |
| 160 | int mbedtls_arc4_self_test( int verbose ) |
| 161 | { |
| 162 | int i, ret = 0; |
| 163 | unsigned char ibuf[8]; |
| 164 | unsigned char obuf[8]; |
| 165 | mbedtls_arc4_context ctx; |
| 166 | |
| 167 | mbedtls_arc4_init( &ctx ); |
| 168 | |
| 169 | for( i = 0; i < 3; i++ ) |
| 170 | { |
| 171 | if( verbose != 0 ) |
| 172 | mbedtls_printf( " ARC4 test #%d: ", i + 1 ); |
| 173 | |
| 174 | memcpy( ibuf, arc4_test_pt[i], 8 ); |
| 175 | |
| 176 | mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 ); |
| 177 | mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf ); |
| 178 | |
| 179 | if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 ) |
| 180 | { |
| 181 | if( verbose != 0 ) |
| 182 | mbedtls_printf( "failed\n" ); |
| 183 | |
| 184 | ret = 1; |
| 185 | goto exit; |
| 186 | } |
| 187 | |
| 188 | if( verbose != 0 ) |
| 189 | mbedtls_printf( "passed\n" ); |
| 190 | } |
| 191 | |
| 192 | if( verbose != 0 ) |
| 193 | mbedtls_printf( "\n" ); |
| 194 | |
| 195 | exit: |
| 196 | mbedtls_arc4_free( &ctx ); |
| 197 | |
| 198 | return( ret ); |
| 199 | } |
| 200 | |
| 201 | #endif /* MBEDTLS_SELF_TEST */ |
| 202 | |
| 203 | #endif /* MBEDTLS_ARC4_C */ |