CryptoSystem.java

//package ecc;

import java.io.*;

/** This interface is used to model a modern cryptosystem. It contains methods 
to encrypt and decrypt and methods to generate keys for the specific cryptosystem.
In an actual implementation it would be a good idea to initialize a key inside
the constructor method.*/
public interface CryptoSystem{

    /**  Encrypts the string p.  
     *@param plain the plaintext to be encrypted.
     *@param ek The (public) key to use for encryption.
     *@return the input string encrypted with the current key.
     */
    public byte[] encrypt(byte[] plain, int numbytes, Key ek);

    /**  Decrypts the string c.  
     *@param cipher the ciphertext to be decrypted.
     *@param sk the (secret) key to use for decryption.
     *@return the input string decrypted with the current key.
     */
    public byte[] decrypt(byte[] cipher, Key dk);

    /** This method generates a new key for the cryptosystem.
     *@return the new key generated*/
    public Key generateKey();

    /** This method returns the maximum size of blocks it can encrypt.
     *@return the maximum block size the system can encrypt. */
    public int blockSize();

    /** Returns a String describing this CryptoSystem*/
    public String toString();
}