var alphabet = "abcdefghijklmnopqrstuvwxyz1234567890@.-";
var alphaLen = alphabet.length;

function vigenere_decrypt (key, chiffre) {
  var i, j = 0;
  var hlp  = 0;
  var text = "";

  chiffre = chiffre.toLowerCase();
  key     = key.toLowerCase();
  for (i=0; i < chiffre.length; i++) {
    hlp = alphabet.indexOf(chiffre.charAt(i));
    if (hlp >= 0) {
      text = text + alphabet.charAt((alphaLen+(hlp-alphabet.indexOf(key.charAt(j))))%alphaLen);
      j = (j+1) % key.length;
    } else text = text + chiffre.charAt(i);
  }
  return text;
}

function spam_protection (key, chiffre) {
  location.href='mailto:'+vigenere_decrypt(key, chiffre);
}