package gnu.crypto;

// ----------------------------------------------------------------------------
// $ID$
//
// Copyright (C) 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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 2, or (at your option)
// any later version.
//
// GNU Crypto 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 this program; see the file COPYING.  If not, write to the
//
//    Free Software Foundation Inc.,
//    59 Temple Place - Suite 330,
//    Boston, MA 02111-1307
//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module.  An independent module is a module which is
// not derived from or based on this library.  If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so.  If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------

import java.util.PropertyPermission;

/**
 * The global run-time property list for the GNU Crypto library. The
 * properties contained in this class (and their values) affect the
 * run-time behavior of certain classes.
 *
 * <p>For example, the boolean property
 * "gnu.crypto.cipher.rejectWeakKeys" will cause the address@hidden
 * gnu.crypto.cipher.IBlockCipher#init(java.util.Map)} method to throw
 * a address@hidden java.security.InvalidKeyException} when initialized with
 * a knows weak key, if the property is true.
 *
 * @version $Revision$
 */
public final class Properties {

   // Constants and variables.
   // -----------------------------------------------------------------------

   /**
    * The properties.
    */
   private static final java.util.Properties props =
      new java.util.Properties();

   // Class methods.
   // -----------------------------------------------------------------------

   /**
    * Gets the value of the given property, or a default value if this
    * property is not set.
    *
    * @param name The name of the property to get.
    * @param def The value to return if the property is not set.
    * @throws IllegalArgumentException If <i>name</i> is null.
    * @throws SecurityException If the caller is not allowed to read the
    * property.
    */
   public static String getProperty(String name, String def) {
      if (name == null)
         throw new IllegalArgumentException();
      SecurityManager sm = System.getSecurityManager();
      if (sm != null) {
         Object ctx = sm.getSecurityContext();
         sm.checkPermission(new PropertyPermission(name, "read"), ctx);
      }
      synchronized (props) {
         return props.getProperty(name, def);
      }
   }

   /**
    * Gets the value of the given property, or null if this property is
    * not set.
    *
    * @param name The name of the property to get.
    * @throws IllegalArgumentException If <i>name</i> is null.
    * @throws SecurityException If the caller is not allowed to read the
    * property.
    */
   public static String getProperty(String name) {
      return getProperty(name, null);
   }

   /**
    * Sets the value of a given property.
    *
    * @param name  The name of the property to set.
    * @param value The new value of this property.
    * @throws IllegalArgumentException If <i>name</i> is null.
    * @throws SecurityException If the caller is not allowed to write the
    * property.
    */
   public static void setProperty(String name, String value) {
      if (name == null)
         throw new IllegalArgumentException();
      SecurityManager sm = System.getSecurityManager();
      if (sm != null) {
         Object ctx = sm.getSecurityContext();
         sm.checkPermission(new PropertyPermission(name, "write"), ctx);
      }
      synchronized (props) {
         props.setProperty(name, value);
      }
   }
}