//==============================================================================
// NullCipherSpi.java
//==============================================================================

package tribble.crypto;


// System imports

import java.lang.Exception;
import java.lang.String;
import java.lang.System;

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.NoSuchPaddingException;


/*******************************************************************************
* Null block cipher.
* Implements a null cryptographic cipher which does not do any actual
* encrypting of data.
*
* <!-- --------------------------------------------------------------------- -->
* @version	API 2, $Revision: 1.2 $ $Date: 2005/09/11 04:08:24 $
* @since	2005-04-25
* @author
*	David R. Tribble
*	(<a href="mailto:david@tribble.com">david@tribble.com</a>).
*
*	<p>
*	Copyright ©2005 by David R. Tribble, all rights reserved.
*	<br>
*	Permission is granted to freely use and distribute this source code
*	provided that the original copyright and authorship notices remain
*	intact.
*/

public final class NullCipherSpi
    extends tribble.crypto.BlockCipherSpi
{
// Identification

    /** Revision information. */
    static final String		REV =
        "@(#)tribble/crypto/NullCipherSpi.java $Revision: 1.2 $ $Date: 2005/09/11 04:08:24 $\n";


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Constants

    /** Algorithm name. */
    private static final String		ALGORITHM =	"Null";

    /** Block size, in bytes. */
    private static final int		BLOCK_SIZE =	8;


    //----------------------------------
    // Test vectors (see #main)

    private static final byte[]		TEST_KEY =
    {
        (byte) 0x44, (byte) 0x61, (byte) 0x76, (byte) 0x69,
        (byte) 0x64, (byte) 0x20, (byte) 0x52, (byte) 0x2E,
        (byte) 0x20, (byte) 0x54, (byte) 0x72, (byte) 0x69,
        (byte) 0x62, (byte) 0x62, (byte) 0x6C, (byte) 0x65,
    };

    private static final byte[]		TEST_PLAINTEXT =
    {
        (byte) 0x01, (byte) 0x23, (byte) 0x45, (byte) 0x67,
        (byte) 0x89, (byte) 0xAB, (byte) 0xCD, (byte) 0xEF,
        (byte) 0x00, (byte) 0xFF, (byte) 0x00, (byte) 0xFF,
        (byte) 0xA5, (byte) 0xC3, (byte) 0xB4, (byte) 0x81,
    };


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Static methods

    /***************************************************************************
    * Test driver.
    *
    * <!-- ----------------------------- -->
    * @param	args
    * Command line arguments.
    *
    * @throws	Exception
    * Thrown if an error occurs in the encryption engine.
    *
    * @since	1.1, 2005-04-25
    */

    public static final void main(String[] args)
        throws Exception
    {
        // Test this cipher SPI
        test(new NullCipherSpi(), TEST_KEY, TEST_PLAINTEXT);
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Variables

    // (None)


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Constructors

    /***************************************************************************
    * Default constructor.
    *
    * @throws	NoSuchAlgorithmException
    * Never thrown.
    *
    * @throws	NoSuchPaddingException
    * Never thrown.
    *
    * @since	1.1, 2005-04-25
    */

    public NullCipherSpi()
        throws NoSuchAlgorithmException, NoSuchPaddingException
    {
        // Initialize
        super(new NullCipher(), MODE_ECB, PADDING_NONE);
        m_alg = ALGORITHM;
        m_blockLen = BLOCK_SIZE;
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Methods

    /***************************************************************************
    * Initialize this cipher.
    *
    * @param	key
    * The symmetric (secret) key for this cipher.
    *
    * @param	decrypt
    * If true, this indicates that this cipher is to be initialized for
    * decrypting, otherwise it is to be initialized for encrypting.
    *
    * @since	1.1, 2005-04-25
    */

    protected void initialize(byte[] key, boolean decrypt)
        throws InvalidKeyException
        //overrides tribble.crypto.SymmetricCipherSpi
    {
/*+++NOT USED
        if (key == null)
            throw new InvalidKeyException("Key missing");
        if (key.length < 1)
            throw new InvalidKeyException("Invalid key length");
        this.m_keyLen = key.length;
+++*/

        this.m_decrypt = decrypt;
    }


    /***************************************************************************
    * Encrypt exactly one block of plaintext.
    *
    * @param	in
    * Array containing a single block of plaintext bytes to encrypt.
    * The length of the block is exactly equal to the cipher block size.
    *
    * @param	inOff
    * Index of the first byte of the plaintext block within array <tt>in</tt> to
    * encrypt.
    *
    * @param	out
    * Array that will be filled with the encrypted ciphertext block.
    * The length of the block is exactly equal to the cipher block size.
    *
    * @param	outOff
    * Index of the first byte of array <tt>out</tt> to fill with the encrypted
    * ciphertext block.
    *
    * @see	#blockDecrypt blockDecrypt()
    * @see	#initialize initialize()
    *
    * @since	1.1, 2005-04-25
    */

    protected void blockEncrypt(/*const*/ byte[] in, int inOff,
        byte[] out, int outOff)
        //overrides tribble.crypto.SymmetricCipherSpi
    {
        // This cipher algorithm does nothing
        for (int i = BLOCK_SIZE;  i > 0;  i--)
            out[outOff++] = in[inOff++];
    }


    /***************************************************************************
    * Decrypt exactly one block of plaintext.
    *
    * @param	in
    * Array containing a single block of ciphertext bytes to decrypt.
    * The length of the block is exactly equal to the cipher block size.
    *
    * @param	inOff
    * Index of the first byte of the ciphertext block within array <tt>in</tt>
    * to decrypt.
    *
    * @param	out
    * Array that will be filled with the decrypted plaintext block.
    * The length of the block is exactly equal to the cipher block size.
    *
    * @param	outOff
    * Index of the first byte of array <tt>out</tt> to fill with the decrypted
    * plaintext block.
    *
    * @see	#blockEncrypt blockEncrypt()
    * @see	#initialize initialize()
    *
    * @since	1.1, 2005-04-25
    */

    protected void blockDecrypt(/*const*/ byte[] in, int inOff,
        byte[] out, int outOff)
        //overrides tribble.crypto.SymmetricCipherSpi
    {
        // This cipher algorithm does nothing
        for (int i = BLOCK_SIZE;  i > 0;  i--)
            out[outOff++] = in[inOff++];
    }
}

// End NullCipherSpi.java