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 org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.Signer;
import org.bouncycastle.crypto.params.AsymmetricKeyParameter;

public abstract class AbstractTlsSigner
    implements TlsSigner
{
    protected TlsContext context;

    public void init(TlsContext context)
    {
        this.context = context;
    }

    public byte[] generateRawSignature(AsymmetricKeyParameter privateKey, byte[] md5AndSha1)
        throws CryptoException
    {
        return generateRawSignature(null, privateKey, md5AndSha1);
    }

    public boolean verifyRawSignature(byte[] sigBytes, AsymmetricKeyParameter publicKey, byte[] md5AndSha1)
        throws CryptoException
    {
        return verifyRawSignature(null, sigBytes, publicKey, md5AndSha1);
    }

    public Signer createSigner(AsymmetricKeyParameter privateKey)
    {
        return createSigner(null, privateKey);
    }

    public Signer createVerifyer(AsymmetricKeyParameter publicKey)
    {
        return createVerifyer(null, publicKey);
    }
}