http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5. 
package org.bouncycastle.util.encoders;


general interface for an translator.

/**
 * general interface for an translator.
 */
public interface Translator
{
    
size of the output block on encoding produced by getDecodedBlockSize()
bytes.

/**
     * size of the output block on encoding produced by getDecodedBlockSize()
     * bytes.
     */
    public int getEncodedBlockSize();

    public int encode(byte[] in, int inOff, int length, byte[] out, int outOff);

    
size of the output block on decoding produced by getEncodedBlockSize()
bytes.

/**
     * size of the output block on decoding produced by getEncodedBlockSize()
     * bytes.
     */
    public int getDecodedBlockSize();

    public int decode(byte[] in, int inOff, int length, byte[] out, int outOff);
}