Interfacing a Numeric Keypad

I am a beginner in interfacing and am currently working on my school project which is to be complete in June.

The module I am currently working is a USB Numeric Keypad. I need the numeric keypad to send signals to the Arduino (MEGA or UNO) and the Arduino will decode the signals in to numbers that will be used to enter in variables.

I believe that I have two choices from where I stand. Either I try to work with the Signals the USB D+ and D- wires emit or Construct a PCB containing a resistive ladder which will be used to create an analogue voltage.

My questions are the following:
1)Which will take the least time?
2)How difficult is it to work with (and decode) the USB protocol?
3)Are there any other options on how to tackle this module?

Pictures of the disassembled Numeric Keypad can be seen below

Thank You

If you want USB input you will need something like a USB Host Shield.

The easiest way to interface a keypad is with the Keypad library. You would separate the USB electronics from the keyboard matrix row and column lines and connect those rows and columns to your Arduino pins.

Thank you for your help.

I will take that approach into consideration. The only drawback of it however is that will take 9 pins and I was hoping of using only one pin.

Sounds like it's time to switch to a Mega. That will give you another 40 or so pins to work with.