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.digests;

import org.bouncycastle.util.Memoable;


implementation of GOST R 34.11-2012 256-bit

/**
 * implementation of GOST R 34.11-2012 256-bit
 */
public final class GOST3411_2012_256Digest
    extends GOST3411_2012Digest
{
    private final static byte[] IV = {
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
        0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
    };

    public GOST3411_2012_256Digest()
    {
        super(IV);
    }

    public GOST3411_2012_256Digest(GOST3411_2012_256Digest other)
    {
        super(IV);
        reset(other);
    }

    public String getAlgorithmName()
    {
        return "GOST3411-2012-256";
    }

    public int getDigestSize()
    {
        return 32;
    }

    public int doFinal(byte[] out, int outOff)
    {
        byte[] result = new byte[64];
        super.doFinal(result, 0);

        System.arraycopy(result, 32, out, outOff, 32);

        return 32;
    }

    public Memoable copy()
    {
        return new GOST3411_2012_256Digest(this);
    }
}