I have started a new blog post where I am designing an encryption engine that can be combined with a small microcontroller to secure serial data. I would appreciate any comments and feedback. You can read the first part of the blog at http://design-foundry.net/2016/10/18/a-simple-encryption-engine-part-1/.
Once I have completed the design of the FPGA/CPLD I am also going to create a simple Adruino shield that can be used to encrypt and decrypt serial data using DesignSpark so you'll get the gerber files too.
Update - Part 2 is now posted online too...