Signapk.java: hide the password

import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;

import org.bouncycastle.util.encoders.Base64;

import java.io.Console;

import java.io.BufferedReader;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

    }

    /**

     * Reads the password from stdin and returns it as a string.

     * Reads the password from console and returns it as a string.

     *

     * @param keyFile The file containing the private key.  Used to prompt the user.

     */

    private static String readPassword(File keyFile) {

        // TODO: use Console.readPassword() when it's available.

        System.out.print("Enter password for " + keyFile + " (password will not be hidden): ");

        System.out.flush();

        BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));

        try {

            return stdin.readLine();

        } catch (IOException ex) {

        Console console;

        char[] pwd;

        if((console = System.console()) != null &&

           (pwd = console.readPassword("[%s]", "Enter password for " + keyFile)) != null){

            return String.valueOf(pwd);

        } else {

            return null;

        }

    }