I don&#x27;t know about the constructions and attack scenarios pertaining to this app, but MAC-then-encrypt is generally <i>insecure</i>; it&#x27;s not &quot;easier to get wrong&quot;, but is itself a flaw (typically: of exposing the cipher to malicious ciphertext, rather than screening it out with a MAC, which is designed to distinguish between valid and invalid ciphertext).