Philip R. Zimmermann wants to protect online privacy. Who could object to that?
He has found out once already. Trained as a computer scientist, he developed a program in 1991 called Pretty Good Privacy, or PGP, for scrambling and unscrambling e-mail messages. It won a following among privacy rights advocates and human rights groups working overseas — and a three-year federal criminal investigation into whether he had violated export restrictions on cryptographic software. The case was dropped in 1996, and Mr. Zimmermann, who lives in Menlo Park, Calif., started PGP Inc. to sell his software commercially.
Now he is again inviting government scrutiny. On Sunday, he released a free Windows software program, Zfone, that encrypts a computer-to-computer voice conversation so both parties can be confident that no one is listening in. It became available earlier this year to Macintosh and Linux users of the system known as voice-over-Internet protocol, or VoIP.
