it would probably stop a casual snooper. i doubt the encryption would stand up to a subpoena or a super computer for long. you dont have to break the private key, just the shared key to open & read the message.
about encryption. The deletion function is nice but like snapchat not precisely true.
i suppose you could confuse snoopers by taking a jpg and saving it as a text file and then transmitting it. the person on the other end renames it as a jpg and reads the message. it just delays any determined snooper. this is the kinda software that attracts snoopers like a fly to sugar - or like British reporters to dead peoples voice mail.
if you and your intended recipient are using a one time pad then added encryption isn't necessary. if well designed, the message is sent out with normal traffic making identifying the 'nugget' difficult.
https://en.wikipedia.org/wiki/One-time_pad
