CryptoSystem.java

/* This file is part of Wattzap Community Edition.
 *
 * Wattzap Community Edtion is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Wattzap Community Edition is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Wattzap.  If not, see <http://www.gnu.org/licenses/>.
*/
package ecc;

/**
 * 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();
}