Cryptographer. Co-author of OpenPGP, DKIM, syslog-sign, ZRTP, the Skein hash function, Threefish cipher, and other things.

Businessman. Co-founder of PGP Corporation, Silent Circle, World Benders, and others. Presently CTO at Entrust.

Software engineer. Worked at the above as well as Apple, DEC, NASA, and others.