code: function(_key,_data){
          var _bkey = __str2bin(_key,!0);
          if (_bkey.length>16)
              _bkey = __data2md5(_bkey,_key.length*__chrsz);
  
          var _ipad = Array(16),
              _opad = Array(16);
          for(var i=0;i<16;i++){
              _ipad[i] = _bkey[i]^0x36363636;
              _opad[i] = _bkey[i]^0x5C5C5C5C;
          }
  
          var _hash = __data2md5(_ipad.concat(
                                 __str2bin(_data,!0)),
                                 512+_data.length*__chrsz);
          return __data2md5(_opad.concat(_hash),512+128);
      }
docs: /*
  Calculate the HMAC-MD5, of a key and some data