Callas had also co-founded several secure comms companies, including including PGP Corp, Silent Circle and Blackphone. A Senate committee is still debating legislation that could compel companies to help law enforcement agencies bypass their own encryption -- something that Apple says would make its products more vulnerable to hacking.

Apple's work on security doesn't stop with this hire. As the WSJ reported a few months back, the company is also working on improving encryption in iCloud. It also recently grabbed Frederic Jacobs, the developer behind Signal, a secure chat app used by Edward Snowden, as an intern.