Is using a service like privnote a plausible way to communicate privately? According to the privacy policy, at no time is any note held in any readable format state on their servers. Also each message 'self destructs' after being opened one time.
People might say that "there are no posted attacks for privnote", but that just means the bad guys haven't told you they can crack your encryption. Since bad guys will never tell you that they can crack your encryption you must not assume lack of evidence of cracks is the same as lack of cracks.
(http://pablohoffman.com/how-privnote-really-works)
There's some stuff that is vaguely worrying about privnote.
Really, learn GPG / PGP. Help other people learn it. Fix the UI. Fix the documentation. Sign everything. Encrypt everything.