I heard* that all smartphones&#x2F;cellphones are inherently insecure because:<p>1. By design, the cellular radio controller (called the baseband) accepts important&#x2F;privileged commands from the cell tower.  (For example, &quot;update firmware&quot;.  Sometimes, there&#x27;s even &quot;read range of bytes from phone&#x27;s internal storage&quot;.)<p>2. Portable fake cell towers exist (called Stringrays).<p>Therefore, unfortunately, it seems unreasonable to claim that private keys generated by this eZing app never leave the phone.<p>* Probably previously here on HN.  Couldn&#x27;t find the link today.<p>UPDATE: This pgp-centric secure email is not open source?  <i></i><i>giggle</i><i></i>  Where do these people come from?