Code Talkers Engineering offers a Non-Disclosure Agreement to cover gaps in your resume. 

Does this NDA actually give you a job when you are unemployed? No.

Does this NDA actually help you learn a skill better than without? Nope.

Does this NDA actually provide an alibi in the event law enforcement wants to know where you were? Not even a little.

It does, however, offer you an alternative response to an interview question. And that isn't too bad. Maybe it becomes an icebreaker. Maybe it becomes a fun story.