Put your passphrase/key in the key box, put your text (either encrypted or plain) in text box, hit the button going the direction you require. The result will show below.
Nothing posted, nothing stored, nothing recorded.
Currently finishing the Android version, its made but needs tarting up, same goes for the Windows desktop and mobile versions. (As does this, but I'll do that when I get the app's finished).
Hideous colour? click a monkey.