/*
* File : $Source: /alkacon/cvs/alkacon/com.alkacon.opencms.commons/src/com/alkacon/opencms/commons/CmsStringCrypter.java,v $
* Date : $Date: 2007/11/30 11:57:27 $
* Version: $Revision: 1.3 $
*
* This file is part of the Alkacon OpenCms Add-On Module Package
*
* Copyright (c) 2007 Alkacon Software GmbH (http://www.alkacon.com)
*
* The Alkacon OpenCms Add-On Module Package 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.
*
* The Alkacon OpenCms Add-On Module Package 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 the Alkacon OpenCms Add-On Module Package.
* If not, see http://www.gnu.org/licenses/.
*
* For further information about Alkacon Software GmbH, please see the
* company website: http://www.alkacon.com.
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org.
*/
package com.alkacon.opencms.commons;
import org.opencms.i18n.CmsEncoder;
import org.opencms.main.CmsLog;
import org.opencms.util.CmsStringUtil;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.logging.Log;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
/**
* This class is responsible for encrypting and decrypting Strings.<p>
*
* The result can be be used as URL parameters.<p>
*
* @author Peter Bonrad
* @author Andreas Zahner
*/
public final class CmsStringCrypter {
/** The encryption to be used. */
private static final String ENCRYPTION = "DES";
/** The format of the key and the values to be crypted. */
private static final String FORMAT = "UTF8";
/** The log object for this class. */
private static final Log LOG = CmsLog.getLog(CmsStringCrypter.class);
/** The default password to be used. */
private static final String PASSWORD_DEFAULT = "fuZe-6jK";
/**
* Hides the public constructor for this utility class.<p>
*/
private CmsStringCrypter() {
// hide constructor
}
/**
* Decrypts the given value which was encrypted with the encrypt method with a default password.<p>
*
* @param value the value to be decrypted
* @return the decrypted string of the value or null if something went wrong
*/
public static String decrypt(String value) {
return decrypt(value, PASSWORD_DEFAULT);
}
/**
* Decrypts the given value which was encrypted with the encrypt method.<p>
*
* @param value the value to be decrypted
* @param password the passsword used for decryption, has to be the same as used for encryption
* @return the decrypted string of the value or null if something went wrong
*/
public static String decrypt(String value, String password) {
// check if given value is valid
if (CmsStringUtil.isEmptyOrWhitespaceOnly(value)) {
if (LOG.isWarnEnabled()) {
LOG.warn(Messages.get().getBundle().key(Messages.LOG_WARN_INVALID_DECRYPT_STRING_1, value));
}
return null;
}
try {
// create key
Key key = new SecretKeySpec(getKey(password), ENCRYPTION);
Cipher cipher = Cipher.getInstance(ENCRYPTION);
cipher.init(Cipher.DECRYPT_MODE, key);
// decode from base64
BASE64Decoder base64decoder = new BASE64Decoder();
value = CmsStringUtil.substitute(value, "-", "+");
value = CmsStringUtil.substitute(value, "_", "/");
byte[] cleartext = base64decoder.decodeBuffer(value);
// decrypt text
byte[] ciphertext = cipher.doFinal(cleartext);
return CmsEncoder.decode(new String(ciphertext));
} catch (Exception ex) {
if (LOG.isErrorEnabled()) {
LOG.error(Messages.get().getBundle().key(Messages.LOG_ERROR_DECRPYT_0), ex);
}
}
return null;
}
/**
* Encrypts the given value with a default password.<p>
*
* @param value the string which should be encrypted
* @return the encrypted string of the value or null if something went wrong
*/
public static String encrypt(String value) {
return encrypt(value, PASSWORD_DEFAULT);
}
/**
* Encrypts the given value.<p>
*
* @param value the string which should be encrypted
* @param password the passsword used for encryption, use the same password for decryption
* @return the encrypted string of the value or null if something went wrong
*/
public static String encrypt(String value, String password) {
// check if given value is valid
if (CmsStringUtil.isEmptyOrWhitespaceOnly(value)) {
if (LOG.isWarnEnabled()) {
LOG.warn(Messages.get().getBundle().key(Messages.LOG_WARN_INVALID_ENCRYPT_STRING_1, value));
}
return null;
}
try {
// create key
byte[] k = getKey(password);
Key key = new SecretKeySpec(k, ENCRYPTION);
Cipher cipher = Cipher.getInstance(ENCRYPTION);
cipher.init(Cipher.ENCRYPT_MODE, key);
// encrypt text
byte[] cleartext = value.getBytes(FORMAT);
byte[] ciphertext = cipher.doFinal(cleartext);
// encode with base64 to be used as a url parameter
BASE64Encoder base64encoder = new BASE64Encoder();
String base64encoded = base64encoder.encode(ciphertext);
base64encoded = CmsStringUtil.substitute(base64encoded, "+", "-");
base64encoded = CmsStringUtil.substitute(base64encoded, "/", "_");
return base64encoded;
} catch (Exception ex) {
if (LOG.isErrorEnabled()) {
LOG.error(Messages.get().getBundle().key(Messages.LOG_ERROR_ENCRYPT_0), ex);
}
}
return null;
}
/**
* Converts the given password to machine readable form.<p>
*
* @param password the password to convert to a machine readable key
* @return the password in machine readable form
*/
private static byte[] getKey(String password) {
try {
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update(password.toString().getBytes());
byte[] key = md5.digest();
// now get the first 8 bytes
byte[] finalKey = new byte[8];
for (int i = 0; i <= 7; i++) {
finalKey[i] = key[i];
}
return finalKey;
} catch (NoSuchAlgorithmException ex) {
if (LOG.isErrorEnabled()) {
LOG.error(Messages.get().getBundle().key(Messages.LOG_ERROR_CREATE_KEY_0), ex);
}
}
return null;
}
}