Answer for https://groups.google.com/forum/?fromgroups=#!topic/play-framework/MF_cQ743vv4

Application.java

/**
 * Answer for https://groups.google.com/forum/?fromgroups=#!topic/play-framework/MF_cQ743vv4
 */

package controllers;

import com.typesafe.config.ConfigFactory;
import play.*;
import play.libs.Crypto;
import play.mvc.*;

import java.io.UnsupportedEncodingException;

public class Application extends Controller {

    public static final String MESSAGE_TO_SIGN = "hello";

    public static Result index() {
        return ok(MESSAGE_TO_SIGN + " signed: " + Crypto.sign(MESSAGE_TO_SIGN));
    }


    public static void main(String[] args) throws UnsupportedEncodingException {
        System.out.println(signWithoutStartingWebServer(MESSAGE_TO_SIGN));
    }

    private static String signWithoutStartingWebServer(String message) throws UnsupportedEncodingException {
        final Configuration configuration = new Configuration(ConfigFactory.load());
        final String secret = configuration.getString("application.secret");
        return Crypto.sign(message, secret.getBytes("utf-8"));
    }
}