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
      );

//±àÂ뺯Êý
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;
}

//½âÂ뺯Êý
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;
}