&quot;Necessary keys are generated within the app so the private key never leaves the device&quot;<p>Funny. With my email+PGP setup, my private key never even enters the device - <a href="https:&#x2F;&#x2F;grepular.com&#x2F;An_NFC_PGP_SmartCard_For_Android" rel="nofollow">https:&#x2F;&#x2F;grepular.com&#x2F;An_NFC_PGP_SmartCard_For_Android</a>