/**
 * Copyright © 2001 The JA-SIG Collaborative.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *u
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the JA-SIG Collaborative
 *    (http://www.jasig.org/)."
 *
 * THIS SOFTWARE IS PROVIDED BY THE JA-SIG COLLABORATIVE "AS IS" AND ANY
 * EXPRESSED 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 JA-SIG COLLABORATIVE OR
 * ITS 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.jasig.portal.security;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Date;


/**
 * <p>A version of md5passwd which can be called from other Java classes to encode a password.</p>
 * Returns an encoded password string.
 *
 * @author rtwigg@uccs.edu
 * (Excerpted from md5passwd authored by Andrew Newman, newman@yale.edu)
 * @version $Revision: 2.41 $
 */
public class Md5 {
  public static String encryptPasswd(String passwd) {
    byte[] hash, rnd = new byte[8], fin = new byte[24];
    Long date = new Long((new Date()).getTime());
    SecureRandom r = new SecureRandom((date.toString()).getBytes());
    MessageDigest md = null;

    try { md = MessageDigest.getInstance("MD5"); } catch (NoSuchAlgorithmException e) {}
    r.nextBytes(rnd);
    md.update(rnd);
    hash = md.digest(passwd.getBytes());
    System.arraycopy(rnd, 0, fin, 0, 8);
    System.arraycopy(hash, 0, fin, 8, 16);
    String encrPwd = (encode(fin));
    return(encrPwd);
  }

//
// This was originally Jonathan B. Knudsen's Example from his book
// Java Cryptography published by O'Reilly Associates (1st Edition 1998)
//

  private static String encode(byte[] raw) {
    StringBuffer encoded = new StringBuffer();
    for (int i = 0; i < raw.length; i += 3) {
      encoded.append(encodeBlock(raw, i));
    }
    return encoded.toString();
  }

  private static char[] encodeBlock(byte[] raw, int offset) {
    int block = 0;
    int slack = raw.length - offset - 1;
    int end = (slack >= 2) ? 2 : slack;
    for (int i = 0; i <= end; i++) {
      byte b = raw[offset + i];
      int neuter = (b < 0) ? b + 256 : b;
      block += neuter << (8 * (2 - i));
    }
    char[] base64 = new char[4];
    for (int i = 0; i < 4; i++) {
      int sixbit = (block >>> (6 * (3 - i))) & 0x3f;
      base64[i] = getChar(sixbit);
    }
    if (slack < 1) base64[2] = '=';
    if (slack < 2) base64[3] = '=';
    return base64;
  }

  private static char getChar(int sixBit) {
    if (sixBit >= 0 && sixBit <= 25)
      return (char)('A' + sixBit);
    if (sixBit >= 26 && sixBit <= 51)
      return (char)('a' + (sixBit - 26));
    if (sixBit >= 52 && sixBit <= 61)
      return (char)('0' + (sixBit - 52));
    if (sixBit == 62) return '+';
    if (sixBit == 63) return '/';
    return '?';
  }

}