Jon Callas, who as co-founder and chief technologist of PGP helped bring strong encryption to the masses, has taken a job with Apple working on operating-system security.

His move around the beginning of the year was confirmed by two of his long-time friends and this brief bio, which says Callas remains on PGP's technical advisory board. He previously served as CTO and CISO of PGP Corporation since its founding in 2002.

Callas is the latest celebrity researcher to join Apple's security team. Last month, former Mozilla security boss Window Snyder, credited with making Firefox's security response more professional, took a job in Cupertino's security department. And in May 2009, One Laptop Per Child's top security architect, Ivan Krstic, signed on to Apple, with the title of "Security Samurai, Core OS."

Callas didn't respond to an email and phone call seeking details. His Linked profile lists his position as "Cryptographer at I Could Tell You But Then I'd Have To Kill You and Associates." His move marks the second time he's been employed at Apple, having worked as a "software developer and researcher focused on new networking and collaboration products" from 1995 to 1997, according to his resume (PDF).

The new gig is the latest stop on a 25-year journey that's also included engineering and software architect positions at the now-defunct Digital Equipment, Counterpane Internet Security (now owned by BT), and Wave Systems. His biggest claim to fame was his involvement at PGP, which successfully marketed one of the first publicly available implementations of public key encryption, written by Phil Zimmermann.

In the 1990s, Callas served as chief scientist of PGP Inc., which was purchased in 1997 by Network Associates. In 2002, as PGP floundered under its new owners, he was instrumental in regaining the rights to the PGP technology and forming PGP Corporation, along with Phil Dunkelberger, who remains the company's CEO.

"He's quite a valuable guy," Zimmermann told The Register. "He has good people skills and good perspectives on his craft, which is cryptography." During much of his tenure, Zimmermann added, Callas focused on the generation, exchange and safe storage of cryptographic keys, a highly complex procedure generally referred to as key management.

Zimmermann and Bruce Schneier, founder of Counterpane, both confirmed Callas's new job.

Callas's precise responsibilities at Apple are unknown. Given his expertise in cryptography and his focus on OS security, it's tempting to speculate he's perfecting FileVault. The security feature built into Mac OS X encrypts only a user's home directory, a shortcoming that allows snoops easy access to many sensitive files that by default are stored elsewhere. While at PGP, Callas oversaw development of software that encrypted Macs' entire hard drive, according to this 2008 article from CNET's Declan McCullagh.

But Callas has stressed that his work is by no means limited to encryption.

"I'm known primary these days as a cryptographer, but I did operating system security for a long time before I did cryptography," he wrote in a 2009 blog post congratulating Apple on the hire of Krstic. "In my own mind, I'm an OS guy who has had a successful side project in crypto."

He went on to share a bit about his approach for safely engineering new software features that ought to serve Apple well as it continues to bring new classes of devices to market.

"The classic problem with designing new OS concepts is ignoring what went before," he wrote. "Any designer of new features and systems needs to answer the question, 'What did MULTICS and VMS do?' The best security of the past is rarely met by the present." ®