text: var _utf8_encode = function (string) {
    string = string.replace(/\r\n/g, "\n");
    var utftext = "";
    for (var n = 0; n < string.length; n++) {
      var c = string.charCodeAt(n);
      if (c < 128) {
        utftext += String.fromCharCode(c);
      } else if ((c > 127) && (c < 2048)) {
        utftext += String.fromCharCode((c >> 6) | 192);
        utftext += String.fromCharCode((c & 63) | 128);
      } else {
        utftext += String.fromCharCode((c >> 12) | 224);
        utftext += String.fromCharCode(((c >> 6) & 63) | 128);
        utftext += String.fromCharCode((c & 63) | 128);
      }
    }
    return utftext;
  };
  md5 = function md5(string) {
    var k, AA, BB, CC, DD, a, b, c, d;
    var S11 = 7, S12 = 12, S13 = 17, S14 = 22;
    var S21 = 5, S22 = 9, S23 = 14, S24 = 20;
    var S31 = 4, S32 = 11, S33 = 16, S34 = 23;
    var S41 = 6, S42 = 10, S43 = 15, S44 = 21;
    string = _utf8_encode(string);
    var x = ConvertToWordArray(string);
    a = 0x67452301;
    b = 0xEFCDAB89;
    c = 0x98BADCFE;
    d = 0x10325476;
    for (k = 0; k < x.length; k += 16) {
      AA = a;
      BB = b;
      CC = c;
      DD = d;
      a = FF(a, b, c, d, x[k], S11, 0xD76AA478);
      d = FF(d, a, b, c, x[k + 1], S12, 0xE8C7B756);
      c = FF(c, d, a, b, x[k + 2], S13, 0x242070DB);
      b = FF(b, c, d, a, x[k + 3], S14, 0xC1BDCEEE);
      a = FF(a, b, c, d, x[k + 4], S11, 0xF57C0FAF);
      d = FF(d, a, b, c, x[k + 5], S12, 0x4787C62A);
      c = FF(c, d, a, b, x[k + 6], S13, 0xA8304613);
      b = FF(b, c, d, a, x[k + 7], S14, 0xFD469501);
      a = FF(a, b, c, d, x[k + 8], S11, 0x698098D8);
      d = FF(d, a, b, c, x[k + 9], S12, 0x8B44F7AF);
      c = FF(c, d, a, b, x[k + 10], S13, 0xFFFF5BB1);
      b = FF(b, c, d, a, x[k + 11], S14, 0x895CD7BE);
      a = FF(a, b, c, d, x[k + 12], S11, 0x6B901122);
      d = FF(d, a, b, c, x[k + 13], S12, 0xFD987193);
      c = FF(c, d, a, b, x[k + 14], S13, 0xA679438E);
      b = FF(b, c, d, a, x[k + 15], S14, 0x49B40821);
      a = GG(a, b, c, d, x[k + 1], S21, 0xF61E2562);
      d = GG(d, a, b, c, x[k + 6], S22, 0xC040B340);
      c = GG(c, d, a, b, x[k + 11], S23, 0x265E5A51);
      b = GG(b, c, d, a, x[k], S24, 0xE9B6C7AA);
      a = GG(a, b, c, d, x[k + 5], S21, 0xD62F105D);
      d = GG(d, a, b, c, x[k + 10], S22, 0x2441453);
      c = GG(c, d, a, b, x[k + 15], S23, 0xD8A1E681);
      b = GG(b, c, d, a, x[k + 4], S24, 0xE7D3FBC8);
      a = GG(a, b, c, d, x[k + 9], S21, 0x21E1CDE6);
      d = GG(d, a, b, c, x[k + 14], S22, 0xC33707D6);
      c = GG(c, d, a, b, x[k + 3], S23, 0xF4D50D87);
      b = GG(b, c, d, a, x[k + 8], S24, 0x455A14ED);
      a = GG(a, b, c, d, x[k + 13], S21, 0xA9E3E905);
      d = GG(d, a, b, c, x[k + 2], S22, 0xFCEFA3F8);
      c = GG(c, d, a, b, x[k + 7], S23, 0x676F02D9);
      b = GG(b, c, d, a, x[k + 12], S24, 0x8D2A4C8A);
      a = HH(a, b, c, d, x[k + 5], S31, 0xFFFA3942);
      d = HH(d, a, b, c, x[k + 8], S32, 0x8771F681);
      c = HH(c, d, a, b, x[k + 11], S33, 0x6D9D6122);
      b = HH(b, c, d, a, x[k + 14], S34, 0xFDE5380C);
      a = HH(a, b, c, d, x[k + 1], S31, 0xA4BEEA44);
      d = HH(d, a, b, c, x[k + 4], S32, 0x4BDECFA9);
      c = HH(c, d, a, b, x[k + 7], S33, 0xF6BB4B60);
      b = HH(b, c, d, a, x[k + 10], S34, 0xBEBFBC70);
      a = HH(a, b, c, d, x[k + 13], S31, 0x289B7EC6);
      d = HH(d, a, b, c, x[k], S32, 0xEAA127FA);
      c = HH(c, d, a, b, x[k + 3], S33, 0xD4EF3085);
      b = HH(b, c, d, a, x[k + 6], S34, 0x4881D05);
      a = HH(a, b, c, d, x[k + 9], S31, 0xD9D4D039);
      d = HH(d, a, b, c, x[k + 12], S32, 0xE6DB99E5);
      c = HH(c, d, a, b, x[k + 15], S33, 0x1FA27CF8);
      b = HH(b, c, d, a, x[k + 2], S34, 0xC4AC5665);
      a = II(a, b, c, d, x[k], S41, 0xF4292244);
      d = II(d, a, b, c, x[k + 7], S42, 0x432AFF97);
      c = II(c, d, a, b, x[k + 14], S43, 0xAB9423A7);
      b = II(b, c, d, a, x[k + 5], S44, 0xFC93A039);
      a = II(a, b, c, d, x[k + 12], S41, 0x655B59C3);
      d = II(d, a, b, c, x[k + 3], S42, 0x8F0CCC92);
      c = II(c, d, a, b, x[k + 10], S43, 0xFFEFF47D);
      b = II(b, c, d, a, x[k + 1], S44, 0x85845DD1);
      a = II(a, b, c, d, x[k + 8], S41, 0x6FA87E4F);
      d = II(d, a, b, c, x[k + 15], S42, 0xFE2CE6E0);
      c = II(c, d, a, b, x[k + 6], S43, 0xA3014314);
      b = II(b, c, d, a, x[k + 13], S44, 0x4E0811A1);
      a = II(a, b, c, d, x[k + 4], S41, 0xF7537E82);
      d = II(d, a, b, c, x[k + 11], S42, 0xBD3AF235);
      c = II(c, d, a, b, x[k + 2], S43, 0x2AD7D2BB);
      b = II(b, c, d, a, x[k + 9], S44, 0xEB86D391);
      a = AddUnsigned(a, AA);
      b = AddUnsigned(b, BB);
      c = AddUnsigned(c, CC);
      d = AddUnsigned(d, DD);
    }
  
    var temp = WordToHex(a) + WordToHex(b) + WordToHex(c) + WordToHex(d);
    return temp.toUpperCase();
  };
  /**
   * @return {number}
   */
  var RotateLeft = function (lValue, iShiftBits) {
    return (lValue << iShiftBits) | (lValue >>> (32 - iShiftBits));
  };
  
  /**
   * @return {number}
   */
  function AddUnsigned(la, lb) {
    var lX4, lY4, lX8, lY8, lResult;
    lX8 = (la & 0x80000000);
    lY8 = (lb & 0x80000000);
    lX4 = (la & 0x40000000);
    lY4 = (lb & 0x40000000);
    lResult = (la & 0x3FFFFFFF) + (lb & 0x3FFFFFFF);
    if (lX4 && lY4) {
      return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
    }
    if (lX4 || lY4) {
      var number = lResult & 0x40000000;
      if (number) {
        return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
      } else {
        return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
      }
    } else {
      return (lResult ^ lX8 ^ lY8);
    }
  }
  
  /**
   * @return {number}
   */
  function F(x, y, z) {
    return (x & y) | ((~x) & z);
  }
  
  /**
   * @return {number}
   */
  function G(x, y, z) {
    return (x & z) | (y & (~z));
  }
  
  /**
   * @return {number}
   */
  function H(x, y, z) {
    return (x ^ y ^ z);
  }
  
  /**
   * @return {number}
   */
  function I(x, y, z) {
    return (y ^ (x | (~z)));
  }
  
  /**
   * @return {number}
   */
  function FF(a, b, c, d, x, s, ac) {
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac));
    return AddUnsigned(RotateLeft(a, s), b);
  }
  
  /**
   * @return {number}
   */
  function GG(a, b, c, d, x, s, ac) {
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac));
  
    return AddUnsigned(RotateLeft(a, s), b);
  }
  
  /**
   * @return {number}
   */
  function HH(a, b, c, d, x, s, ac) {
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac));
    return AddUnsigned(RotateLeft(a, s), b);
  }
  
  /**
   * @return {number}
   */
  function II(a, b, c, d, x, s, ac) {
    a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac));
    return AddUnsigned(RotateLeft(a, s), b);
  }
  
  function ConvertToWordArray(string) {
    var lWordCount;
    var lMessageLength = string.length;
    var lNumberOfWords_temp1 = lMessageLength + 8;
    var lNumberOfWords_temp2 =
        (lNumberOfWords_temp1 - (lNumberOfWords_temp1 % 64)) / 64;
    var lNumberOfWords = (lNumberOfWords_temp2 + 1) * 16;
    var lWordArray = new Array(lNumberOfWords - 1);
    var lBytePosition = 0;
    var lByteCount = 0;
    while (lByteCount < lMessageLength) {
      lWordCount = (lByteCount - (lByteCount % 4)) / 4;
      lBytePosition = (lByteCount % 4) * 8;
      lWordArray[lWordCount] = (lWordArray[lWordCount] | (string.charCodeAt(
          lByteCount) << lBytePosition));
      lByteCount++;
    }
    lWordCount = (lByteCount - (lByteCount % 4)) / 4;
    lBytePosition = (lByteCount % 4) * 8;
    lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80 << lBytePosition);
    lWordArray[lNumberOfWords - 2] = lMessageLength << 3;
    lWordArray[lNumberOfWords - 1] = lMessageLength >>> 29;
    return lWordArray;
  }
  
  /**
   * @return {string}
   */
  function WordToHex(lValue) {
    var WordToHexValue = "", WordToHexValue_temp = "", lByte, lCount;
    for (lCount = 0; lCount <= 3; lCount++) {
      lByte = (lValue >>> (lCount * 8)) & 255;
      WordToHexValue_temp = "0" + lByte.toString(16);
      WordToHexValue =
          WordToHexValue + WordToHexValue_temp.substr(
          WordToHexValue_temp.length - 2, 2);
    }
    return WordToHexValue;
  }
  
  // private property
  var _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
  // public method for encoding
  base64 = function (input) {
    var output = "";
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
    var i = 0;
    input = _utf8_encode(input);
    while (i < input.length) {
      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);
    }
    return output;
  };
  
  signClient = function (options) {
    signClient.allowableClientTimeDifference = options.allowableClientTimeDifference;
    if (undefined === signClient.allowableClientTimeDifference) {
      signClient.allowableClientTimeDifference = 0;
    }
    signClient.verifyUserAgent = options.verifyUserAgent;
    signClient.clientSecret = options.clientSecret;
    signClient.parameterName = options.parameterName || 'sign';
  
    signClient.toQueryString = function (data) {
      var str = '', index = 0, length = Object.keys(data).length;
      for (var i in data) {
        str += i + '=' + data[i];
        index++;
        if (index < length) {
          str += '&'
        }
      }
      return str;
    };
    signClient.sign = function (data) {
      var type = typeof data, timestamp = new Date().getTime();
      if ('string' === type) {
        var datap = {}, paramstr = data.split('&');
        for (var p in paramstr) {
          var kv = paramstr[p].split('=');
          if (kv.length < 2) {
            continue;
          }
          datap[kv[0]] = kv[1];
        }
        data = datap;
      }
  
      var keys = Object.keys(data).sort();
      var prestr = '';
      for (var i in keys) {
        var key = keys[i], value = data[key];
        if (value === undefined || value === null || value === ''
            || key.toUpperCase() === "sign".toUpperCase()
            || key.toUpperCase() === "sign_type".toUpperCase()) {
          continue;
        }
        prestr = prestr + key + "=" + value + "&";
      }
      if (signClient.allowableClientTimeDifference <= 0
          && !signClient.verifyUserAgent) {
        return md5(prestr + signClient.clientSecret)
      } else {
        var paramsSign = md5(prestr
            + signClient.clientSecret).substring(0, 16),
  
            userAgentSign = md5(
                navigator.userAgent
                + signClient.clientSecret).substring(
                16, 24),
            timeSign = md5(Math.floor(
                timestamp / (signClient.allowableClientTimeDifference
                * 1000))
                + signClient.clientSecret).substring(24, 32);
        return paramsSign + userAgentSign + timeSign;
      }
    }
  };
  