Anyone have an http iApp template with cookie encryption??

What version of BIG-IP are you using?

The included f5.http iApp with versions 11.4 and beyond actually allows for this, though it isn't part of the default deployment.

The first step is to build a Cookie Persistence Profile with Cookie Encryption Policy set the way you desire. Then, use the f5.http iApp, and switch to "Advanced" configuration mode. You will find a way to select the Cookie Persistence Profile that you created with the first step in the "Virtual Servers and Pools" section.

Hopefully this is sufficient. If this doesn't work for you, let us know.