package fr.in2p3.jsaga.adaptor.security;
   
   import javax.crypto.Cipher;
   import javax.crypto.KeyGenerator;
   import javax.crypto.spec.SecretKeySpec;
   
   import org.apache.commons.codec.binary.Base64;
   
   import java.io.File;
  import java.io.FileOutputStream;
  import java.security.Key;
  
  /* ***************************************************
  * *** Centre de Calcul de l'IN2P3 - Lyon (France) ***
  * ***             http://cc.in2p3.fr/             ***
  * ***************************************************
  * File:   PasswordEncrypterSingleton
  * Author: Sylvain Reynaud (sreynaud@in2p3.fr)
  * Date:   21 sept. 2007
  * ***************************************************
  * Description:                                      */
  /**
   *
   */
  public class PasswordEncrypterSingleton extends PasswordAbstract {
      private static final int EXPIRY_DATE_POSITION = 12;
      private static final int KEY_SIZE = 128;
  
      /**
       * @param keyalias the alias of the secret key
       * @param lifetime the validity duration of the key in seconds
       */
      public PasswordEncrypterSingleton(String keyalias, int lifetime) throws Exception {
          super();
  
          // generate key
          KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);
          keyGenerator.init(KEY_SIZE);
          Key key = keyGenerator.generateKey();
  
          // modify it
          byte[] rawKey = key.getEncoded();
          int expiryDate = getExpiryDate(lifetime);
          setBytes(rawKey, EXPIRY_DATE_POSITION, expiryDate);
          m_key = new SecretKeySpec(rawKey, ALGORITHM);
  
          // store it
          File keystoreFile = PasswordAbstract.KEYSTORE_FILE;
          m_keystore.setKeyEntry(keyalias, m_key, m_keypass, null);
          m_keystore.store(new FileOutputStream(keystoreFile), m_storepass);
      }
  
      public String encrypt(String uncrypted) throws Exception {
          Cipher cipher = Cipher.getInstance(CIPHER);
          cipher.init(Cipher.ENCRYPT_MODE, m_key);
          byte[] crypted = cipher.doFinal(uncrypted.getBytes());
          return Base64.encodeBase64String(crypted);
      }
  
      public static int getExpiryDate(int lifetime) {
          return (int) (System.currentTimeMillis()/1000) + lifetime;
      }
  
      private static void setBytes(byte[] bytes, int pos, int value) {
          bytes[pos] = (byte)((value & 0xff000000)>>>24);
          bytes[pos+1] = (byte)((value & 0x00ff0000)>>>16);
          bytes[pos+2] = (byte)((value & 0x0000ff00)>>>8);
          bytes[pos+3] = (byte)((value & 0x000000ff));
      }
  }