code: function ab2hex(ab) {
        var dv = new DataView(ab)
          , i
          , len
          , hex = ''
          , c
          ;
  
        for (i = 0, len = dv.byteLength; i < len; i += 1) {
          c = dv.getUint8(i).toString(16);
  
          if (c.length < 2) {
            c = '0' + c;
          }
  
          hex += c;
        }
  
        return hex;
      }
docs: convert from arraybuffer to hex