/*
 * Copyright (c) 2003, KNOPFLERFISH project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 * - Neither the name of the KNOPFLERFISH project nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.knopflerfish.service.um.useradmin;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Utility class for one-way encryption of, for example, user passwords.
 *
 * @author  Gatespace AB
 * @version $Revision: 1.1.1.1 $
 */
public class PasswdUtil {
  private static MessageDigest md;
  static {
    try {
      md = MessageDigest.getInstance( "SHA" );
    }
    catch( NoSuchAlgorithmException ex ) {}
  }

  /**
   * Create salt and the a digest of the salt and the message.
   *
   * @param message the message to calculate a digest for
   * @param digest buffer to write the resulting digest to, must be at least
   * 20 bytes long.
   * @return the salt used when calculating the digest.
   */
  public static synchronized byte[] saltAndDigest( String message,
						   byte[] digest ) {
    byte[] salt = Long.toString(System.currentTimeMillis()).getBytes();
    try {
      byte[] msg = message.getBytes("UTF-8");
      md.update( salt );
      md.update( msg );
      md.digest( digest, 0, 20 );
    } catch (Exception ex) {}

    return salt;
  }

  /**
   * Create a digest from salt and a message.
   *
   * @param message the message to calculate a digest for
   * @param salt the salt to use.
   * @return the resulting digest, will be 20 bytes long.
   */
  public static synchronized byte[] digest( String message, byte[] salt ) {
    try {
      byte[] msg = message.getBytes("UTF-8");
      md.update( salt );
      md.update( msg );
    } catch (Exception ex) {}
    return md.digest();
  }

}