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.jce.exception;


This is an extended exception. Java before version 1.4 did not offer the
possibility the attach a cause to an exception. The cause of an exception is
the Throwable object which was thrown and caused the
exception. This interface must be implemented by all exceptions to accomplish
this additional functionality.

/**
 * 
 * This is an extended exception. Java before version 1.4 did not offer the
 * possibility the attach a cause to an exception. The cause of an exception is
 * the <code>Throwable</code> object which was thrown and caused the
 * exception. This interface must be implemented by all exceptions to accomplish
 * this additional functionality.
 * 
 */
public interface ExtException
{

    
Returns the cause of the exception.

Returns:The cause of the exception.
/**
     * Returns the cause of the exception.
     * 
     * @return The cause of the exception.
     */
    Throwable getCause();
}