Kate

I have preserved a comment block written by the author of the encode64/decode64 functions. My contributions are also public domain.

base64.js

// This code was written by Tyler Akins and has been placed in the
// public domain.  It would be nice if you left this header intact.
// Base64 code from Tyler Akins -- http://rumkin.com

var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

function encode64(input)
{
  var output = "", output2 = "";
  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 += keyStr.charAt(enc1) +
              keyStr.charAt(enc2) +
              keyStr.charAt(enc3) +
              keyStr.charAt(enc4);
  }
  while (i < input.length);

  i = 0;

  while (i < output.length)
  {
    if ((i > 0) && (i % 76 == 0)) output2 += '\n';
    output2 += output[i];
    i++;
  }

  if (output2[output2.length -1] != '\n')
    output2 += '\n';

  return output2;
}


if (!view.hasSelection()) view.selectAll();

c = view.selectionStartColumn;
l = view.selectionStartLine;
t = encode64(view.selection());
document.editBegin();
view.removeSelectedText();
document.insertText(l, c, t);
document.editEnd();

unbase64.js

// This code was written by Tyler Akins and has been placed in the
// public domain.  It would be nice if you left this header intact.
// Base64 code from Tyler Akins -- http://rumkin.com

var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

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 =
   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);
      }
   } while (i < input.length);

   return output;
}

if (!view.hasSelection()) view.selectAll();

c = view.selectionStartColumn;
l = view.selectionStartLine;
t = decode64(view.selection());
document.editBegin();
view.removeSelectedText();
document.insertText(l, c, t);
document.editEnd();