/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.resource.security;

import java.security.acl.Group;
import java.security.Principal;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.util.Map;
import java.math.BigInteger;
import javax.resource.spi.security.PasswordCredential;
import javax.security.auth.Subject;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.login.LoginException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import org.jboss.security.SimplePrincipal;
import org.jboss.logging.Logger;

/** An example of how one could encrypt the database password for a jca
  connection factory. The corresponding  
 
<application-policy name = "HsqlDbRealm">
   <authentication>
      <login-module code = "org.jboss.resource.security.SecureIdentityLoginMdule"
         flag = "required">
         <module-option name = "username">sa</module-option>
         <module-option name = "password">-207a6df87216de44</module-option>
         <module-option name = "managedConnectionFactoryName">jboss.jca:servce=LocalTxCM,name=DefaultDS</module-option>
      </login-module>
   </authentication>
</application-policy>

 This uses a hard-coded cipher algo of Blowfish, and key derived from the
 phrase 'jaas is the way'. Adjust to your requirements.

 * @author Scott.Stark@jboss.org
 * @version $Revision: 1.1.2.3 $
 */
public class SecureIdentityLoginModule
   extends AbstractPasswordCredentialLoginModule
{
   /**
    * Class logger
    */
   private static final Logger log = Logger.getLogger(SecureIdentityLoginModule.class);

   private String username;
   private String password;

   public void initialize(Subject subject, CallbackHandler handler, Map sharedState, Map options)
   {
      super.initialize(subject, handler, sharedState, options);
      username = (String) options.get("username");
      if( username == null )
      {
         throw new IllegalArgumentException("The username is a required option");
      }
      password = (String) options.get("password");
      if( password == null )
      {
         throw new IllegalArgumentException("The password is a required option");
      }
   }

   public boolean login() throws LoginException
   {
      log.trace("login called");
      if( super.login() == true )
         return true;

      super.loginOk = true;
      return true;
   }

   public boolean commit() throws LoginException
   {
      Principal principal = new SimplePrincipal(username);
      SubjectActions.addPrincipals(subject, principal);
      sharedState.put("javax.security.auth.login.name", username);
      // Decode the encrypted password
      try
      {
         char[] decodedPassword = decode(password);
         PasswordCredential cred = new PasswordCredential(username, decodedPassword);
         cred.setManagedConnectionFactory(getMcf());
         SubjectActions.addCredentials(subject, cred);
      }
      catch(Exception e)
      {
         log.debug("Failed to decode password", e);
         throw new LoginException("Failed to decode password: "+e.getMessage());
      }
      return true;
   }

   public boolean abort()
   {
      username = null;
      password = null;
      return true;
   }

   protected Principal getIdentity()
   {
      log.trace("getIdentity called, username="+username);
      Principal principal = new SimplePrincipal(username);
      return principal;
   }

   protected Group[] getRoleSets() throws LoginException
   {
      Group[] empty = new Group[0];
      return empty;
   }

   private static String encode(String secret)
      throws NoSuchPaddingException, NoSuchAlgorithmException,
      InvalidKeyException, BadPaddingException, IllegalBlockSizeException
   {
      byte[] kbytes = "jaas is the way".getBytes();
      SecretKeySpec key = new SecretKeySpec(kbytes, "Blowfish");

      Cipher cipher = Cipher.getInstance("Blowfish");
      cipher.init(Cipher.ENCRYPT_MODE, key);
      byte[] encoding = cipher.doFinal(secret.getBytes());
      BigInteger n = new BigInteger(encoding);
      return n.toString(16);
   }

   private static char[] decode(String secret)
      throws NoSuchPaddingException, NoSuchAlgorithmException,
      InvalidKeyException, BadPaddingException, IllegalBlockSizeException
   {
      byte[] kbytes = "jaas is the way".getBytes();
      SecretKeySpec key = new SecretKeySpec(kbytes, "Blowfish");

      BigInteger n = new BigInteger(secret, 16);
      byte[] encoding = n.toByteArray();
      
      Cipher cipher = Cipher.getInstance("Blowfish");
      cipher.init(Cipher.DECRYPT_MODE, key);
      byte[] decode = cipher.doFinal(encoding);
      return new String(decode).toCharArray();
   }

   /** Main entry point to encrypt a password using the hard-coded pass phrase 
    * 
    * @param args - [0] = the password to encode
    * @throws Exception
    */ 
   public static void main(String[] args) throws Exception
   {
      String encode = encode(args[0]);
      System.out.println("Encoded password: "+encode);
   }
}
