Kobo● Global eBook retailer● “We believe consumers should be able to read any book, anytime, anywhere, and on the device of their choice”● “We believe open standards for eBooks are best for consumers, publishers, retailers and hardware manufacturers. Closed systems stifle innovation and growth. Kobo proudly supports EPUB and encourages our users to read a Kobo-purchased eBook on their smartphone, Sony Reader, laptop, or whichever device they choose.”
● I BUY books. I dont “lend them under certain terms”.● $10 for a digital copy, and you restrict how I use it?
NOTICE● I ONLY WANTED TO ACHIEVE INTEROPABILITY WITH OTHER PROGRAMS ● THAT ARE NOT COMPETING WITH THE KOBO READER● KOBOPIER ONLY REPRODUCES THE DECRYPTION INTERFACE● DONT PIRATE XOR DONT GET CAUGHT
On the right track!● Then: “Is it possible?”● Now: “How to make it practical?”● More patching: Dumping all parts of the key ● Caller of the decryption method creates the key ● Three strings as input ● Does some weirdass stuff, more on that later
Key parts/OzEca8ESalQNvd/xknj8g==ee13373-bb8a-5a09-ccdd-af9c4fbgf844503668452247539May the logs be with you.
Hashing IDs && Base64 decode● H(DeviceID || UserID).substring(16);● Algorithms (hardcoded arrays/tables) look intimidating in smali● Public Domain Base64.java :)
Result: Kobopier http://sporkbomb.eu/kobopier/* Kobopier - a Kobo Android ePub DRM stripper** You can reach the author at email@example.com.* New versions of Kobopier will be made available at http://sporkbomb.eu/kobopier/.** Important note: Kobopier is not made for piracy. It does not break any encryption,* it simply replicates a few steps the original Android Kobo reader does.* Please read the license below. Also, consider that it is YOUR responsibility to deal* with any legal issues that arise from YOU using this tool.* If you buy one copy of an ebook, decrypt it with this tool and then give it away,* thats fine with me - but you alone are responsible if Kobo sues you.** Copyright (C) 2011 sporkbomb