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I wrote a small application to understand ARCFOUR use .


for some reason the encrypted text changes each time i run it :

So if i store it in a file and read it from file after 30 minuts i
can't decrypt it .


but if i run this as it is it works fine


#include <stdio.h>
#include <gcrypt.h>
#include <assert.h>

int read2 ( char * filename , char * buffer , size_t size )
{
FILE * fp = NULL;
fp = fopen ( filename , "rb" );
if ( fp == NULL ) return 1;

fread ( buffer, size, 1, fp );
fclose ( fp );
}

int write2 ( char * filename , char * buffer , size_t size )
{
FILE * fp = NULL;
fp = fopen ( filename , "wb" );
if ( fp == NULL ) return 1;
fwrite ( buffer, size, 1, fp );
fclose ( fp );
}


int main()
{

gcry_cipher_hd_t handle;
gcry_cipher_hd_t handle2;
gcry_error_t err = 0;
char * plain_text ;
char * out ;
char * deout ;
int i ;
char key[] = "This is really strange , i read the documentation i
googled for two days and nothing , i can't encrypt && decrypt";
char text[] = "Text to encrypt bla bla bla bla bla bla bla soo
This is really strange , i read the documentation i googled for two
days and nothing , i can't encrypt && decrypt";

size_t size_of_plain_text = strlen ( text ) + 1;
size_t size_of_buffers = size_of_plain_text ;

plain_text = ( char * ) malloc ( size_of_plain_text );
out = ( char * ) malloc ( size_of_buffers );
deout = ( char * ) malloc ( size_of_buffers );


assert ( plain_text );

assert ( out );
assert ( deout );


//Just null all

for ( i = 0 ;i < size_of_buffers; i++ )
{
out[i] = '0';
deout[i] = '0';
}

strcpy ( plain_text , text );


gcry_check_version ( NULL );
gcry_control ( GCRYCTL_DISABLE_SECMEM_WARN );
gcry_control ( GCRYCTL_INIT_SECMEM, 16384, 0 );


{

err = gcry_cipher_open ( &handle2,
GCRY_CIPHER_ARCFOUR,GCRY_CIPHER_MODE_STREAM,0 );
err = gcry_cipher_open ( &handle,
GCRY_CIPHER_ARCFOUR,GCRY_CIPHER_MODE_STREAM,0 );

if ( err )
{
fprintf ( stderr, "Failure: %s/%s\n",
gcry_strsource ( err ),
gcry_strerror ( err ) );

}
err = gcry_cipher_setkey ( handle , key ,256 );
err = gcry_cipher_setkey ( handle2 , key,256 );
if ( err )
{
fprintf ( stderr, "Failure: %s/%s\n",
gcry_strsource ( err ),
gcry_strerror ( err ) );

}
}
err = gcry_cipher_encrypt ( handle,
( unsigned char * ) out,
size_of_buffers , ( const unsigned char * )
plain_text,size_of_plain_text );
if ( err )
{
fprintf ( stderr, "Failure: %s/%s\n",
gcry_strsource ( err ),
gcry_strerror ( err ) );

}

write2 ( "/tmp/encrypt",out,size_of_buffers );
for ( i = 0 ;i < size_of_buffers; i++ )
out[i] = '0';
read2 ( "/tmp/encrypt",out,size_of_buffers );
err = gcry_cipher_encrypt ( handle2,
( unsigned char * ) deout,
size_of_buffers, ( const unsigned char * ) out,size_of_buffers );
if ( err )
{
fprintf ( stderr, "Failure: %s/%s\n",
gcry_strsource ( err ),
gcry_strerror ( err ) );

}
printf ( "The result is : %d\n%s\n%s\n", strcmp ( deout,text
),deout , text );

free ( plain_text );
free ( out );
free ( deout );
gcry_cipher_close ( handle );
gcry_cipher_close ( handle2 );
return 0;

}

- --
- ---==== Jabka Atu ===---
bsh83.blogspot.com
- ---=== Encryption is a way of life ===---
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