INTELLIGENCE OPERATIONS: Phone Taps Just Got Impossible April 12, 2006: Eavesdropping on phone calls just got a lot harder. Phil Zimmermann, the guy who invented PGP encryption for Internet mail, has developed a similar product, Zfone, for VOIP (telephone calls over the Internet). Zfone, like PGP, is free and easy to use. PGP drove intelligence agencies nuts, because it gave criminals and terrorists access to industrial grade cryptography. PGP doesn't stop the police or intel people from reading encrypted email, but it does slow them down. Zfone, however, uses stronger encryption. This means more delays, perhaps fatal delays, in finding...