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. 
package org.bouncycastle.crypto.tls;

import java.io.IOException;

public interface TlsSignerCredentials extends TlsCredentials
{
    byte[] generateCertificateSignature(byte[] md5andsha1) throws IOException;
}