/* * Copyright (C) 1995, 1996 Systemics Ltd (http://www.systemics.com/) * All rights reserved. * * This library and applications are FREE FOR COMMERCIAL AND NON-COMMERCIAL USE * as long as the conditions within the COPYRIGHT file are adhered to. * */ package java.crypt;/** * This class implements the SHA message digest. * <p>The native code SHA implementation used by the class was * developed by Peter C. Gutmann from the implementation in * Bruce Schneiers "Applied Cryptography". * <p>Copyright (C) 1995, 1996 Systemics Ltd (http://www.systemics.com/) * All rights reserved. * * @version     1.00, 12/02/1996 * @author      Systemics (Michael Wynn) */public final class SHA extends MessageDigest{	/**	 * This is the length of the final hash (in bytes).	 */	public static final int HASH_LENGTH = 20;	static	{		// load the dll that contains the native code implementation of the		// hash algorithnms.		System.loadLibrary("sha");	}	/**	 * This is the amount of data required by the native code.	 */	private static final int INT_BUFFER_LENGTH = 94;	/**	 * contextBuffer required by the native code.	 */    private byte contextBuf[];		/* SHA data buffer */	/**	 * The public constructor.	 */	public SHA()	{		contextBuf = new byte[INT_BUFFER_LENGTH];		reset();	}	/**	 * Return length of the hash (in bytes).	 * @see #HASH_LENGTH	 * @return   The length of the hash.	 */	public int length()	{		return HASH_LENGTH;	}			/**	 * Initialise (reset) the message digest.	 */	public void reset()	{		init();	}	/**	 * Returns the digest of the data added and resets the digest.	 * @return    the digest of all the data added to the message digest.	 */	public byte[] digest()	{		byte buf[] = new byte[HASH_LENGTH];		finish( buf );		return buf;	}	/**	 * Add data to the message digest (calls the native code).	 * @param data    The data to be added.	 * @param offset  The start of the data in the array.	 * @param length  The amount of data to add.	 */	protected void addToDigest( byte data[], int offset, int length )	{		update( data, offset, length );	}	// The native functions that implement SHA	/**	 * Resets the Context buffer to initial values.	 */	private native void init();	/**	 * Adds to the hash.	 * @param data    The data to be added.	 * @param offset  The start of the data within the array.	 * @param length  The amount of data to add.	 */	private native void update( byte data[], int offset, int length );	/**	 * Fills the buffer with the digested output and resets the digest.	 * @param output   The buffer where the digest is to be stored.	 */	private native void finish( byte output[] );}