/*
    * Copyright 2013 smartics, Kronseder & Reiner GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package de.smartics.properties.security.esapi;
  
  import org.apache.commons.codec.binary.Base64;
  import org.owasp.esapi.Encryptor;
  import org.owasp.esapi.crypto.CipherText;
  import org.owasp.esapi.crypto.PlainText;
  import org.owasp.esapi.errors.EncryptionException;
  
  import de.smartics.properties.api.core.domain.PropertyCode;
  import de.smartics.properties.api.core.domain.PropertyDescriptor;
  import de.smartics.properties.api.core.domain.PropertyDescriptorMessageBean;
  import de.smartics.properties.api.core.security.SecurityException;
  import de.smartics.properties.api.core.security.PropertyValueSecurity;
  
  /**
   * Base implementation based on OWASP ESAPI.
   */
  public abstract class AbstractEsapiPropertyValueSecurity implements
      PropertyValueSecurity
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    /**
     * The class version identifier.
     */
    private static final long serialVersionUID = 1L;
  
    // --- members --------------------------------------------------------------
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor.
     */
    public AbstractEsapiPropertyValueSecurity()
    {
    }
  
    // ****************************** Inner Classes *****************************
  
    // ********************************* Methods ********************************
  
    // --- init -----------------------------------------------------------------
  
    // --- get&set --------------------------------------------------------------
  
    // --- business -------------------------------------------------------------
  
    @Override
    public String decrypt(final PropertyDescriptor descriptor,
        final String encryptedValue) throws SecurityException
    {
      try
      {
        final Encryptor encryptor = provideEncryptor();
        final byte[] bytes = Base64.decodeBase64(encryptedValue);
        final CipherText cipherText =
            CipherText.fromPortableSerializedBytes(bytes);
        final PlainText plainText = encryptor.decrypt(cipherText);
        final String plainValue = plainText.toString();
        return plainValue;
      }
      catch (final EncryptionException e)
      {
        throw new SecurityException(new PropertyDescriptorMessageBean(
            PropertyCode.SECURITY, e, descriptor));
      }
    }
  
    /**
     * Provides the encryptor to use for encryption.
     *
     * @return the encryptor to use for encryption.
     * @throws EncryptionException on any encryption problem.
     */
    protected abstract Encryptor provideEncryptor() throws EncryptionException;
  
    @Override
    public String encrypt(final PropertyDescriptor descriptor,
        final String plainValue) throws SecurityException
   {
     try
     {
       final Encryptor encryptor = provideEncryptor();
       final PlainText plainText = new PlainText(plainValue);
       final CipherText cipherText = encryptor.encrypt(plainText);
       final byte[] bytes = cipherText.asPortableSerializedByteArray();
       final String encryptedValue = Base64.encodeBase64String(bytes);
       return encryptedValue;
     }
     catch (final EncryptionException e)
     {
       throw new SecurityException(new PropertyDescriptorMessageBean(
           PropertyCode.SECURITY, e, descriptor));
     }
   }
 
   // --- object basics --------------------------------------------------------
 
 }