I was concerned about securing my projects to my clients, having to burn some fuses in the chip is not enough, so i decided to add a small chip that acts as a key. the key has two modes , encode and decode configurable from a jumper switch.

The chip communicates through a serial port and uses aes or hash/sha1 encryption.

it can be used to validate a key before loading the main program or used to validate a section of the code.

I am still working on my prototype but will publish more details as i progress along.

*UPDATE 24/5/2017

I added TWI communication, it can now be wired in circuit and user can use the function to access the chip engine.