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.IOException;

public interface TlsSignerCredentials
    extends TlsCredentials
{
    byte[] generateCertificateSignature(byte[] hash)
        throws IOException;

    SignatureAndHashAlgorithm getSignatureAndHashAlgorithm();
}