function randomChar() {
  var securityWord = new Array("esel", "bank", "toor", "blau", "rot", "grün", "@wer", "@§$%", "Haus", "Fahne", "Schiene" );
  
  var word = securityWord[(Math.round(Math.random() * 10) % (securityWord.length-1)) + 1];
  var number = (Math.round(Math.random() * 10) % word.length) + 1;
  
  var text = "<label for=\"char\">Geben sie bitte das " + number +
             ". Zeichen<br\/> im Wort '<b>" + word +
             "<\/b>' ein*<\/label><input type=\"hidden\" name=\"char1\" value=\"" + word.charAt(number-1) +
             "\"\/>";
  
  document.write(text);
}

function openWindow(uri) {
  window.open(uri,'blank','toolbar=no');
}