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.tls;

import java.io.ByteArrayOutputStream;

import org.bouncycastle.crypto.Digest;

class DigestInputBuffer extends ByteArrayOutputStream
{
    void updateDigest(Digest d)
    {
        d.update(this.buf, 0, count);
    }
}