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.modes.kgcm;

public class BasicKGCMMultiplier_512
    implements KGCMMultiplier
{
    private final long[] H = new long[KGCMUtil_512.SIZE];

    public void init(long[] H)
    {
        KGCMUtil_512.copy(H,  this.H);
    }

    public void multiplyH(long[] z)
    {
        KGCMUtil_512.multiply(z, H, z);
    }
}