Here are some whitepapers and blogpapers that should help you get started/learn more about hardware security. I’ve divided the page into divisions for easier viewing.
I’ll keep adding to the list when I remember any other sites/papers that I refer to. Please let me know of any mistakes/suggestions down in the comments!
General hardware reverse engineering/ attacks
LayerOne talk on hardware reverse engineering [Check the other parts too]
Bluetooth Low Energy
Side channel attacks
Video for the above talk: https://www.youtube.com/watch?v=i27NiVuWmhE
Books to read:
http://www.amazon.com/Android-Hackers-Handbook-Joshua-Drake/dp/111860864X/ [Good section on hardware hacking]