#include <string.h>
#define KEYSIZE 8


/*************************************************************
 ** crypto is a very simple 'Block cipher' encryption class **
 *************************************************************/
class Crypto {
private:
	char key[KEYSIZE+1];
public:
	Crypto(char *inputkey); 
	char *blockcipher(char *data, int max);
};
 



/*****************************************************
 ** constructor initialized with a key that is used **
 ** to both encrypt and decrypt the same data.      **
 *****************************************************/
Crypto::Crypto(char *inputkey)
{
	strncpy(key,inputkey,KEYSIZE);
	srand(42);			// the answer to the Universe
    int x = rand();
	for (int j=0; j<KEYSIZE; j++){
		key[j] = key[j] ^ x;
	}
	key[j]='\0';
}


/***************************************************************
 ** blockcipher() is just a vanilla blockcipher that performs **
 ** an XOR of a key against a block of data.  max is used     **
 ** to enable crypting of a partial block, ie less than the   **
 ** KEYSIZE.                                                  **
 ***************************************************************/
char *Crypto::blockcipher(char *data, int max=KEYSIZE)
{
	static char result[KEYSIZE+1];

	for (int j=0; j<max; j++){
		result[j] = data[j] ^ key[j];
	}
	result[j]='\0';
	return result;
}