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Cryptographic framework allowing the implementation of cryptographic protocols, e.g. e-voting.
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/*
 * UniCrypt
 *
 *  UniCrypt(tm): Cryptographical framework allowing the implementation of cryptographic protocols e.g. e-voting
 *  Copyright (c) 2016 Bern University of Applied Sciences (BFH), Research Institute for
 *  Security in the Information Society (RISIS), E-Voting Group (EVG)
 *  Quellgasse 21, CH-2501 Biel, Switzerland
 *
 *  Licensed under Dual License consisting of:
 *  1. GNU Affero General Public License (AGPL) v3
 *  and
 *  2. Commercial license
 *
 *
 *  1. This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Affero General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 Affero General Public License for more details.
 *
 *   You should have received a copy of the GNU Affero General Public License
 *   along with this program.  If not, see .
 *
 *
 *  2. Licensees holding valid commercial licenses for UniCrypt may use this file in
 *   accordance with the commercial license agreement provided with the
 *   Software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and Bern University of Applied Sciences (BFH), Research Institute for
 *   Security in the Information Society (RISIS), E-Voting Group (EVG)
 *   Quellgasse 21, CH-2501 Biel, Switzerland.
 *
 *
 *   For further information contact 
 *
 *
 * Redistributions of files must retain the above copyright notice.
 */
package ch.bfh.unicrypt.math.function.classes;

import ch.bfh.unicrypt.ErrorCode;
import ch.bfh.unicrypt.UniCryptRuntimeException;
import ch.bfh.unicrypt.helper.random.RandomByteSequence;
import ch.bfh.unicrypt.math.algebra.general.interfaces.Element;
import ch.bfh.unicrypt.math.algebra.general.interfaces.Set;
import ch.bfh.unicrypt.math.function.abstracts.AbstractFunction;

/**
 * This class represents the concept of a generalized identity function f:X->X^n with f(x)=(x,...,x) for all elements x
 * in X. This class represents the concept of an identity function f:X->X with f(x)=x for all elements x in X.
 * 
 * @author R. Haenni
 * @author R. E. Koenig
 * @version 1.0
 */
public class IdentityFunction
	   extends AbstractFunction {

	private static final long serialVersionUID = 1L;

	private IdentityFunction(final Set set) {
		super(set, set);
	}

	@Override
	protected Element abstractApply(final Element element, final RandomByteSequence randomByteSequence) {
		return element;
	}

	/**
	 * This is the default constructor for this class. It creates a generalized identity function for a given group,
	 * which reproduces the input value multiple time.
	 * 
	 * @param set The given set
	 * @return Returns an instance of this class
	 */
	public static IdentityFunction getInstance(final Set set) {
		if (set == null) {
			throw new UniCryptRuntimeException(ErrorCode.NULL_POINTER);
		}
		return new IdentityFunction(set);
	}

}