/* DigitalSignature.java */

import java.io.*;
import java.security.cert.Certificate;
import java.security.*;

public class DigitalSignature
{
  static final String KEYSTORE = "c:\\windows\\.keystore";
  static final char[] KSPASS   = {'h','j','p','3','k','s'};
  static final String ALIAS    = "hjp3";
  static final char[] KEYPASS  = {'h','j','p','3','k','e','y'};

  public static void main(String[] args)
  {
    try {
      //Laden der Schlüsseldatenbank
      KeyStore ks = KeyStore.getInstance("JKS");
      FileInputStream ksin = new FileInputStream(KEYSTORE);
      ks.load(ksin, KSPASS);
      ksin.close();
      //Privaten Schlüssel "hjp3" lesen
      Key key = ks.getKey(ALIAS, KEYPASS);
      //Signatur-Objekt erstellen
      Signature signature = Signature.getInstance("SHA/DSA");
      signature.initSign((PrivateKey)key);
      //Eingabedatei einlesen
      FileInputStream in = new FileInputStream(args[0]);
      int len;
      byte[] data = new byte[1024];
      while ((len = in.read(data)) > 0) {
        //Signatur updaten
        signature.update(data, 0, len);
      }
      in.close();
      //Signatur berechnen
      byte[] result = signature.sign();
      //Signatur ausgeben
      FileOutputStream out = new FileOutputStream(args[1]);
      out.write(result, 0, result.length);
      out.close();
    } catch (Exception e) {
      System.err.println(e.toString());
      System.exit(1);
    }
  }
}