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 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto;


With FIPS PUB 202 a new kind of message digest was announced which supported extendable output, or variable digest sizes.
This interface provides the extra method required to support variable output on an extended digest implementation.

/**
 * With FIPS PUB 202 a new kind of message digest was announced which supported extendable output, or variable digest sizes.
 * This interface provides the extra method required to support variable output on an extended digest implementation.
 */
public interface Xof
    extends ExtendedDigest
{
    
Output the results of the final calculation for this digest to outLen number of bytes.

Params:
  • out – output array to write the output bytes to.
  • outOff – offset to start writing the bytes at.
  • outLen – the number of output bytes requested.
Returns:the number of bytes written
/**
     * Output the results of the final calculation for this digest to outLen number of bytes.
     *
     * @param out output array to write the output bytes to.
     * @param outOff offset to start writing the bytes at.
     * @param outLen the number of output bytes requested.
     * @return the number of bytes written
     */
    int doFinal(byte[] out, int outOff, int outLen);

    
Start outputting the results of the final calculation for this digest. Unlike doFinal, this method
will continue producing output until the Xof is explicitly reset, or signals otherwise.

Params:
  • out – output array to write the output bytes to.
  • outOff – offset to start writing the bytes at.
  • outLen – the number of output bytes requested.
Returns:the number of bytes written
/**
     * Start outputting the results of the final calculation for this digest. Unlike doFinal, this method
     * will continue producing output until the Xof is explicitly reset, or signals otherwise.
     *
     * @param out output array to write the output bytes to.
     * @param outOff offset to start writing the bytes at.
     * @param outLen the number of output bytes requested.
     * @return the number of bytes written
     */
    int doOutput(byte[] out, int outOff, int outLen);
}