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package gnu.crypto.key.dh;

// ----------------------------------------------------------------------------
// $Id: DHKeyPairRawCodec.java,v 1.1 2003/09/26 23:50:48 raif Exp $
//
// 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 gnu.crypto.Registry;
import gnu.crypto.key.IKeyPairCodec;

import java.io.ByteArrayOutputStream;
import java.math.BigInteger;
import java.security.PrivateKey;
import java.security.PublicKey;

/**
 * An object that implements the {@link IKeyPairCodec} operations for the
 * Raw format to use with Diffie-Hellman keypairs.
 *
 * @version $Revision: 1.1 $
 */
public class DHKeyPairRawCodec implements IKeyPairCodec {

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

   // Constructor(s)
   // -------------------------------------------------------------------------

   // implicit 0-arguments ctor

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

   // Instance methods
   // -------------------------------------------------------------------------

   // gnu.crypto.keys.IKeyPairCodec interface implementation -------------------

   public int getFormatID() {
    return RAW_FORMAT;
   }

   /**
    * Returns the encoded form of the designated Diffie-Hellman public key
    * according to the Raw format supported by this library.
    *
    * The Raw format for a DH public key, in this implementation, is
    * a byte sequence consisting of the following:
    *
    * 
    *    4-byte magic consisting of the value of the literal
    *    {@link Registry#MAGIC_RAW_DH_PUBLIC_KEY},

    *    
1-byte version consisting of the constant: 0x01,
    *    4-byte count of following bytes representing the DH parameter
    *    q in internet order,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter q,
    *    4-byte count of following bytes representing the DH parameter
    *    p in internet order,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter p,
    *    4-byte count of following bytes representing the DH parameter
    *    g,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter g,
    *    4-byte count of following bytes representing the DH parameter
    *    y,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter y,
    * 
    *
    * @param key the key to encode.
    * @return the Raw format encoding of the designated key.
    * @throws IllegalArgumentException if the designated key is not a DH one.
    * @see Registry#MAGIC_RAW_DH_PUBLIC_KEY
    */
   public byte[] encodePublicKey(PublicKey key) {
    if (!(key instanceof GnuDHPublicKey)) {
       throw new IllegalArgumentException("key");
    }

    GnuDHPublicKey dhKey = (GnuDHPublicKey) key;
    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    // magic
    baos.write(Registry.MAGIC_RAW_DH_PUBLIC_KEY[0]);
    baos.write(Registry.MAGIC_RAW_DH_PUBLIC_KEY[1]);
    baos.write(Registry.MAGIC_RAW_DH_PUBLIC_KEY[2]);
    baos.write(Registry.MAGIC_RAW_DH_PUBLIC_KEY[3]);

    // version
    baos.write(0x01);

    // q
    byte[] buffer = dhKey.getQ().toByteArray();
    int length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // p
    buffer = dhKey.getParams().getP().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // g
    buffer = dhKey.getParams().getG().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // y
    buffer = dhKey.getY().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    return baos.toByteArray();
   }

   public PublicKey decodePublicKey(byte[] k) {
    // magic
    if (k[0] != Registry.MAGIC_RAW_DH_PUBLIC_KEY[0]
          || k[1] != Registry.MAGIC_RAW_DH_PUBLIC_KEY[1]
          || k[2] != Registry.MAGIC_RAW_DH_PUBLIC_KEY[2]
          || k[3] != Registry.MAGIC_RAW_DH_PUBLIC_KEY[3]) {
       throw new IllegalArgumentException("magic");
    }

    // version
    if (k[4] != 0x01) {
       throw new IllegalArgumentException("version");
    }
    int i = 5;
    int l;
    byte[] buffer;

    // q
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger q = new BigInteger(1, buffer);

    // p
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger p = new BigInteger(1, buffer);

    // g
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger g = new BigInteger(1, buffer);

    // y
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger y = new BigInteger(1, buffer);

    return new GnuDHPublicKey(q, p, g, y);
   }

   /**
    * Returns the encoded form of the designated Diffie-Hellman private key
    * according to the Raw format supported by this library.
    *
    * The Raw format for a DH private key, in this implementation, is
    * a byte sequence consisting of the following:
    *
    * 
    *    4-byte magic consisting of the value of the literal
    *    {@link Registry#MAGIC_RAW_DH_PRIVATE_KEY},

    *    
1-byte version consisting of the constant: 0x01,
    *    4-byte count of following bytes representing the DH parameter
    *    q,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter q,
    *    4-byte count of following bytes representing the DH parameter
    *    p in internet order,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter p,
    *    4-byte count of following bytes representing the DH parameter
    *    g,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter g,
    *    4-byte count of following bytes representing the DH parameter
    *    x,
    *    n-bytes representation of a {@link BigInteger} obtained by invoking
    *    the toByteArray() method on the DH parameter x,
    * 
    *
    * @param key the key to encode.
    * @return the Raw format encoding of the designated key.
    * @throws IllegalArgumentException if the designated key is not a DH one.
    * @see Registry#MAGIC_RAW_DH_PRIVATE_KEY
    */
   public byte[] encodePrivateKey(PrivateKey key) {
    if (!(key instanceof GnuDHPrivateKey)) {
       throw new IllegalArgumentException("key");
    }

    GnuDHPrivateKey dhKey = (GnuDHPrivateKey) key;
    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    // magic
    baos.write(Registry.MAGIC_RAW_DH_PRIVATE_KEY[0]);
    baos.write(Registry.MAGIC_RAW_DH_PRIVATE_KEY[1]);
    baos.write(Registry.MAGIC_RAW_DH_PRIVATE_KEY[2]);
    baos.write(Registry.MAGIC_RAW_DH_PRIVATE_KEY[3]);

    // version
    baos.write(0x01);

    // q
    byte[] buffer = dhKey.getQ().toByteArray();
    int length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // p
    buffer = dhKey.getParams().getP().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // g
    buffer = dhKey.getParams().getG().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    // x
    buffer = dhKey.getX().toByteArray();
    length = buffer.length;
    baos.write( length >>> 24        );
    baos.write((length >>> 16) & 0xFF);
    baos.write((length >>>  8) & 0xFF);
    baos.write( length         & 0xFF);
    baos.write(buffer, 0, length);

    return baos.toByteArray();
   }

   public PrivateKey decodePrivateKey(byte[] k) {
    // magic
    if (k[0] != Registry.MAGIC_RAW_DH_PRIVATE_KEY[0]
          || k[1] != Registry.MAGIC_RAW_DH_PRIVATE_KEY[1]
          || k[2] != Registry.MAGIC_RAW_DH_PRIVATE_KEY[2]
          || k[3] != Registry.MAGIC_RAW_DH_PRIVATE_KEY[3]) {
       throw new IllegalArgumentException("magic");
    }

    // version
    if (k[4] != 0x01) {
       throw new IllegalArgumentException("version");
    }
    int i = 5;
    int l;
    byte[] buffer;

    // q
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger q = new BigInteger(1, buffer);

    // p
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger p = new BigInteger(1, buffer);

    // g
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger g = new BigInteger(1, buffer);

    // x
    l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
    buffer = new byte[l];
    System.arraycopy(k, i, buffer, 0, l);
    i += l;
    BigInteger x = new BigInteger(1, buffer);

    return new GnuDHPrivateKey(q, p, g, x);
   }
}