CueCat USB barcode scanner hacked!

Last week I ordered a CueCat USB barcode scanner from LibraryThing. Today I gave it a first try, on my new book Pragmatic Version Control Using Git. Eager to try my new toy that I had envisioned to ease the process of adding my books to a database I plugged it in, observed that it was recognised as a HID, tried to scan the barcode, and out came this gibberish: .C3nZC3nZC3n2C3P3DxP6DxnY.fHmc.E3zXDhv1C3nYDNzY.

Quite disappointed, I realized that this thing might not be easily used with Linux after all. I searched on Google for CueCat, and soon realized that the stupid scanner outputs a serial number unique to this scanner, followed by the type of barcode and finally the barcode number, and all this is encrypted with CueCat's sophisticated "XOR with C"-cipher:

#!/usr/bin/perl -n 
# Copyright: Larry Wall
printf "Serial: %s  Type: %s  Code: %s\n", 
    map { 
        tr/a-zA-Z0-9+-/ -_/; 
        $_ = unpack 'u', chr(32 + length()*3/4) . $_; 
        s/\0+$//; 
        $_ ^= "C" x length; 
    } /\.([^.]+)/g;

So I foresaw that this dongle was going to be a pain to use. But after some more reading, I came across this page that shows me how to hack the CueCat and disable the encryption alltogether. So disassembled the device and cut pin number 5, like this:


After reassembling the scanner, I tried it on my book again. And lo and behold, there was the real ISBN number I had been looking for: 9781934356159!