This app is powered by libgdx (for the GUI).
The ciphering is made with gwt crypto.
The source is fully open just appropriate it as you which.
The cipher currently is AES 128 bits, even to cipher the key. The ciphered key can be saved but take care if you do so to not compromise it. Your key will be ciphered by a AES_CBC with key and clear your own inputed key. So this app cannot be used as an open Crypto wrapper. It is just doing what I need, the text can only be unciphered with this own app. That was done on purpose.
If you are looking for open crypto libs and crossplatform, just look and javax.crypto or gwt crytpo.