HashHelper.java

package de.fhb.autobday.commons;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Formatter;

/**
 * This class generates a SHA1- or MD5-hashvalue of a string.
 *
 * @author Michael Koppen mail: koppen@fh-brandenburg.de
 */
public class HashHelper {

	/**
	 * This method calcutates the hash.
	 */
	private static String calculateHash(MessageDigest algorithm, String pw) throws UnsupportedEncodingException {

		// get the hash value as byte array
		byte[] hash = algorithm.digest(pw.getBytes("UTF-8"));

		return byteArray2Hex(hash);
	}

	/**
	 * formats the Byte-Array in a Hexvalue.
	 */
	private static String byteArray2Hex(byte[] hash) {
		Formatter formatter = new Formatter();
		for (byte b : hash) {
			formatter.format("%02x", b);
		}
		return formatter.toString();
	}

	/**
	 * This input-method generates the SHA1-hashvalue of a String.
	 *
	 * @param pw
	 * @return hashvalue - String
	 * @throws UnsupportedEncodingException
	 * @throws NoSuchAlgorithmException
	 */
	public static String calcSHA1(String pw)
			throws UnsupportedEncodingException, NoSuchAlgorithmException {

		MessageDigest sha1 = MessageDigest.getInstance("SHA1");

		return calculateHash(sha1, pw);
	}

	/**
	 * This input-method generates the MD5-hashvalue of a String.
	 *
	 * @param pw
	 * @return hashvalue - String
	 * @throws UnsupportedEncodingException
	 * @throws NoSuchAlgorithmException
	 */
	public static String calcMD5(String pw)
			throws UnsupportedEncodingException, NoSuchAlgorithmException {

		MessageDigest md5 = MessageDigest.getInstance("MD5");

		return calculateHash(md5, pw);
	}
}