var keyStr = "ABCDEFGHIJKLMNOP" +
              "QRSTUVWXYZabcdef" +
              "ghijklmnopqrstuv" +
              "wxyz0123456789+/" +
              "=";
  
  function encode64(input) {
    var output = "";
    var chr1, chr2, chr3 = "";
    var enc1, enc2, enc3, enc4 = "";
    var i = 0;
  
    do {
       chr1 = input.charCodeAt(i++);
       chr2 = input.charCodeAt(i++);
       chr3 = input.charCodeAt(i++);
  
       enc1 = chr1 >> 2;
       enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
       enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
       enc4 = chr3 & 63;
  
       if (isNaN(chr2)) {
          enc3 = enc4 = 64;
       } else if (isNaN(chr3)) {
          enc4 = 64;
       }
  
       output = output + 
          keyStr.charAt(enc1) + 
          keyStr.charAt(enc2) + 
          keyStr.charAt(enc3) + 
          keyStr.charAt(enc4);
       chr1 = chr2 = chr3 = "";
       enc1 = enc2 = enc3 = enc4 = "";
    } while (i < input.length);
  
    return output;
  }
  
  function decode64(input) {
    var output = "";
    var chr1, chr2, chr3 = "";
    var enc1, enc2, enc3, enc4 = "";
    var i = 0;
  
    // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
    var base64test = /[^A-Za-z0-9\+\/\=]/g;
    if (base64test.exec(input)) {
       alert("There were invalid base64 characters in the input text.\n" +
             "Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='\n" +
             "Expect errors in decoding.");
    }
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
  
    do {
       enc1 = keyStr.indexOf(input.charAt(i++));
       enc2 = keyStr.indexOf(input.charAt(i++));
       enc3 = keyStr.indexOf(input.charAt(i++));
       enc4 = keyStr.indexOf(input.charAt(i++));
  
       chr1 = (enc1 << 2) | (enc2 >> 4);
       chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
       chr3 = ((enc3 & 3) << 6) | enc4;
  
       output = output + String.fromCharCode(chr1);
  
       if (enc3 != 64) {
          output = output + String.fromCharCode(chr2);
       }
       if (enc4 != 64) {
          output = output + String.fromCharCode(chr3);
       }
  
       chr1 = chr2 = chr3 = "";
       enc1 = enc2 = enc3 = enc4 = "";
  
    } while (i < input.length);
  
    return output;
  }
   
  function mailto(who)
  {
    location = 'mailto:' + decode64(who);
  }