from GDUFS video

base64.js

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var base64DecodeChars = new Array(
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
     52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
     -1,　0,　1,　2,　3, 4,　5,　6,　7,　8,　9, 10, 11, 12, 13, 14,
     15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
     -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
     41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);
function base64encode(str) {
     var out, i, len;
     var c1, c2, c3;
     len = str.length;
     i = 0;
     out = "";
     while(i < len) {
 c1 = str.charCodeAt(i++) & 0xff;
 if(i == len)
 {
      out += base64EncodeChars.charAt(c1 >> 2);
      out += base64EncodeChars.charAt((c1 & 0x3) << 4);
      out += "==";
      break;
 }
 c2 = str.charCodeAt(i++);
 if(i == len)
 {
      out += base64EncodeChars.charAt(c1 >> 2);
      out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
      out += base64EncodeChars.charAt((c2 & 0xF) << 2);
      out += "=";
      break;
 }
 c3 = str.charCodeAt(i++);
 out += base64EncodeChars.charAt(c1 >> 2);
 out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
 out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));
 out += base64EncodeChars.charAt(c3 & 0x3F);
     }
     return out;
}
function base64decode(str) {
     var c1, c2, c3, c4;
     var i, len, out;
     len = str.length;
     i = 0;
     out = "";
     while(i < len) {
 /* c1 */
 do {
      c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
 } while(i < len && c1 == -1);
 if(c1 == -1)
      break;
 /* c2 */
 do {
      c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
 } while(i < len && c2 == -1);
 if(c2 == -1)
      break;
 out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
 /* c3 */
 do {
      c3 = str.charCodeAt(i++) & 0xff;
      if(c3 == 61)
  return out;
      c3 = base64DecodeChars[c3];
 } while(i < len && c3 == -1);
 if(c3 == -1)
      break;
 out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
 /* c4 */
 do {
      c4 = str.charCodeAt(i++) & 0xff;
      if(c4 == 61)
  return out;
      c4 = base64DecodeChars[c4];
 } while(i < len && c4 == -1);
 if(c4 == -1)
      break;
 out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
     }
     return out;
}
function utf16to8(str) {
     var out, i, len, c;
     out = "";
     len = str.length;
     for(i = 0; i < len; i++) {
 c = str.charCodeAt(i);
 if ((c >= 0x0001) && (c <= 0x007F)) {
      out += str.charAt(i);
 } else if (c > 0x07FF) {
      out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
      out += String.fromCharCode(0x80 | ((c >>　6) & 0x3F));
      out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
 } else {
      out += String.fromCharCode(0xC0 | ((c >>　6) & 0x1F));
      out += String.fromCharCode(0x80 | ((c >>　0) & 0x3F));
 }
     }
     return out;
}
function utf8to16(str) {
     var out, i, len, c;
     var char2, char3;
     out = "";
     len = str.length;
     i = 0;
     while(i < len) {
 c = str.charCodeAt(i++);
 switch(c >> 4)
 {
  case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
      // 0xxxxxxx
      out += str.charAt(i-1);
      break;
  case 12: case 13:
      // 110x xxxx　 10xx xxxx
      char2 = str.charCodeAt(i++);
      out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
      break;
  case 14:
      // 1110 xxxx　10xx xxxx　10xx xxxx
      char2 = str.charCodeAt(i++);
      char3 = str.charCodeAt(i++);
      out += String.fromCharCode(((c & 0x0F) << 12) | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
      break;
 }
     }
     return out;
}

function doit() {
     var f = document.f
     f.output.value = base64encode(utf16to8(f.source.value))
     f.decode.value = utf8to16(base64decode(f.output.value))
}