Class MD2

Implemented Interfaces:
Cloneable, IMessageDigest

public class MD2
extends BaseHash

An implementation of the MD2 message digest algorithm.

MD2 is not widely used. Unless it is needed for compatibility with existing systems, it is not recommended for use in new applications.


  1. The MD2 Message-Digest Algorithm.
    B. Kaliski.
  2. The RFC ERRATA PAGE under section RFC 1319.

Field Summary

Fields inherited from class

blockSize, buffer, count, hashSize, name

Constructor Summary

Creates a new MD2 digest ready for use.

Method Summary

This method may be called to create a new copy of the Object.
protected byte[]
protected byte[]
Generates an array of padding bytes.
protected void
protected void
transform(byte[] in, int off)
Adds BLOCK_LENGTH bytes to the running digest.

Methods inherited from class

blockSize, clone, digest, getResult, hashSize, name, padBuffer, reset, resetContext, selfTest, transform, update, update, update

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details


public MD2()
Creates a new MD2 digest ready for use.

Method Details


public Object clone()
This method may be called to create a new copy of the Object. The typical behavior is as follows:
  • o == o.clone() is false
  • o.getClass() == o.clone().getClass() is true
  • o.equals(o) is true

However, these are not strict requirements, and may be violated if necessary. Of the three requirements, the last is the most commonly violated, particularly if the subclass does not override Object.equals(Object).

If the Object you call clone() on does not implement Cloneable (which is a placeholder interface), then a CloneNotSupportedException is thrown. Notice that Object does not implement Cloneable; this method exists as a convenience for subclasses that do.

Object's implementation of clone allocates space for the new Object using the correct class, without calling any constructors, and then fills in all of the new field values with the old field values. Thus, it is a shallow copy. However, subclasses are permitted to make a deep copy.

All array types implement Cloneable, and override this method as follows (it should never fail):

 public Object clone()
   catch (CloneNotSupportedException e)
       throw new InternalError(e.getMessage());
Specified by:
clone in interface IMessageDigest
clone in interface BaseHash
a copy of the Object
See Also:


protected byte[] getResult()
getResult in interface BaseHash


protected byte[] padBuffer()
Generates an array of padding bytes. The padding is defined as i bytes of value i, where i is the number of bytes to fill the last block of the message to BLOCK_LENGTH bytes (or BLOCK_LENGTH bytes when the last block was completely full).
padBuffer in interface BaseHash
the bytes to pad the remaining bytes in the buffer before completing a hash operation.


protected void resetContext()
resetContext in interface BaseHash


public boolean selfTest()
Specified by:
selfTest in interface IMessageDigest
selfTest in interface BaseHash


protected void transform(byte[] in,
                         int off)
Adds BLOCK_LENGTH bytes to the running digest.
transform in interface BaseHash
in - the byte array to take the BLOCK_LENGTH bytes from.
off - the offset to start from in the given byte array. -- Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc. This file is a part of GNU Classpath. GNU Classpath 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 of the License, or (at your option) any later version. GNU Classpath 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 GNU Classpath; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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.