Crypter is a fully fledged crypto app that can decrypt and encrypt any arbitrary data. This version has been released and fully tested for macOS (OSX), Linux (for all distros via AppImage) and Windows (32 & 64 bit). All core modules (modules that provide the core functionality) are fully tested (90%+ coverage). Some end-to-end tests have been written but end-to-end testing is still mostly a WIP.
Crypter uses a MasterPass (obtained at setup) to derive a MasterPassKey using the PBKDF2 key derivation algorithm from the MasterPass (see below for spec). It then derives very secure encryption keys that are used for the encryption of files from the MasterPassKey using the PBKDF2 key derivation algorithm again. This method allows for the generation of very secure encryption keys for data encryption. Moreover, by just publicly storing the credentials used to derive the MasterPassKey and the salts used to derive the encryption keys you have the flexibility of deriving the encryption keys whenever you need to and not having to worry about storing them securely. All you have to do is remember your MasterPass.