Your messages are secured during their entire life span using the same encryption algorithms approved for top secret information. They can only be read by you and the recipients on authorized devices.
Wickr then deletes all metadata from its communications and our Secure File Shredder cleans the RAM after each message or picture is opened.
We unfortunately can't prevent someone from using a camera to take a picture of a message on a screen, but maybe in the future we can come up with a way to stop even that!
On Android we can block in-phone screen capture, however, on iOS we can't prevent screenshots and instead notify the other user(s) that a screenshot has been taken.
If you'd like to know more about the technical details of how we keep your messages private, please feel free to read about it here: Wickr's Core Crypto Goes Public, or for a more concise version, here: How Wickr's Security Works.