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.pqc.crypto.sphincs;

import org.bouncycastle.util.Arrays;

public class SPHINCSPrivateKeyParameters
    extends SPHINCSKeyParameters
{
    private final byte[] keyData;

    public SPHINCSPrivateKeyParameters(byte[] keyData)
    {
        super(true, null);
        this.keyData = Arrays.clone(keyData);
    }

    public SPHINCSPrivateKeyParameters(byte[] keyData, String treeDigest)
    {
        super(true, treeDigest);
        this.keyData = Arrays.clone(keyData);
    }

    public byte[] getKeyData()
    {
        return Arrays.clone(keyData);
    }
}