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/*
* An implementation of the ARCFOUR algorithm
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* The ARCFOUR algorithm was publicly disclosed on 94/09.
*
* http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
*/
#include "common.h"
#if defined(MBEDTLS_ARC4_C)
#include "mbedtls/arc4.h"
#include "mbedtls/platform_util.h"
#include <string.h>
#include "mbedtls/platform.h"
#if !defined(MBEDTLS_ARC4_ALT)
void mbedtls_arc4_init( mbedtls_arc4_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_arc4_context ) );
}
void mbedtls_arc4_free( mbedtls_arc4_context *ctx )
{
if( ctx == NULL )
return;
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_arc4_context ) );
}
/*
* ARC4 key schedule
*/
void mbedtls_arc4_setup( mbedtls_arc4_context *ctx, const unsigned char *key,
unsigned int keylen )
{
int i, j, a;
unsigned int k;
unsigned char *m;
ctx->x = 0;
ctx->y = 0;
m = ctx->m;
for( i = 0; i < 256; i++ )
m[i] = (unsigned char) i;
j = k = 0;
for( i = 0; i < 256; i++, k++ )
{
if( k >= keylen ) k = 0;
a = m[i];
j = ( j + a + key[k] ) & 0xFF;
m[i] = m[j];
m[j] = (unsigned char) a;
}
}
/*
* ARC4 cipher function
*/
int mbedtls_arc4_crypt( mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
unsigned char *output )
{
int x, y, a, b;
size_t i;
unsigned char *m;
x = ctx->x;
y = ctx->y;
m = ctx->m;
for( i = 0; i < length; i++ )
{
x = ( x + 1 ) & 0xFF; a = m[x];
y = ( y + a ) & 0xFF; b = m[y];
m[x] = (unsigned char) b;
m[y] = (unsigned char) a;
output[i] = (unsigned char)
( input[i] ^ m[(unsigned char)( a + b )] );
}
ctx->x = x;
ctx->y = y;
return( 0 );
}
#endif /* !MBEDTLS_ARC4_ALT */
#if defined(MBEDTLS_SELF_TEST)
/*
* ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
*
* http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
*/
static const unsigned char arc4_test_key[3][8] =
{
{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
};
static const unsigned char arc4_test_pt[3][8] =
{
{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
};
static const unsigned char arc4_test_ct[3][8] =
{
{ 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
{ 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
{ 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
};
/*
* Checkup routine
*/
int mbedtls_arc4_self_test( int verbose )
{
int i, ret = 0;
unsigned char ibuf[8];
unsigned char obuf[8];
mbedtls_arc4_context ctx;
mbedtls_arc4_init( &ctx );
for( i = 0; i < 3; i++ )
{
if( verbose != 0 )
mbedtls_printf( " ARC4 test #%d: ", i + 1 );
memcpy( ibuf, arc4_test_pt[i], 8 );
mbedtls_arc4_setup( &ctx, arc4_test_key[i], 8 );
mbedtls_arc4_crypt( &ctx, 8, ibuf, obuf );
if( memcmp( obuf, arc4_test_ct[i], 8 ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto exit;
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
}
if( verbose != 0 )
mbedtls_printf( "\n" );
exit:
mbedtls_arc4_free( &ctx );
return( ret );
}
#endif /* MBEDTLS_SELF_TEST */
#endif /* MBEDTLS_ARC4_C */
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