[strongSwan] Good information on adding custom ESP encryption

[Yeagley, Josiah]

I've been trying to search for good information on how to add custom encryption for encrypting the payload portion of packets sent over an IPSec tunnel. I'm learned that the ESP encryption is done in the kernel and that I'll have to create a kernel module using the kernel's CryptoApi. However, everything I am finding on the subject seems to be rather old (circa 2009 as the latest) and most of the stuff I am finding doesn't really explain how exactly I can go about making the kernel module and getting IPSec (strongSwan) to use it. Does anyone know of any tutorials or good examples I can use/follow that explains how this can be done and how it all works?? Any help will be greatly appreciated.

Thank you for your time, 

~Josiah s. Yeagley