Encrypting VOIP Calls with

By Larry Seltzer  |  Posted 2006-05-22 Print this article Print

Softphones"> The average VOIP user (Im one of these) gets VOIP through a service provider, a phone or cable company, or even a third party like Vonage, which supplies a box for the user to connect to a network and phone system. Its purposely designed so that the user doesnt have to do any VOIP network management.
This puts the provider in a position where it can, if law enforcement requests it, "tap" the phone by storing and forwarding the communications to said authorities. (In fact, I can imagine pretty sophisticated management software that could be made available to law enforcement.)
But what about a more sophisticated user who chooses to use a "softphone" like CounterPaths X-Lite, Gizmo or SJPhone? These are programs that run on a PC (or a Mac or whatever) and over which the communications provider has no control. Such users now have the ability to use strong encryption in the form of Zfone, a free (at least as in speech) encryption system for SIP (Session Initiation Protocol) phones. Zfone was written by crypto-advocate Phil Zimmerman, once vigorously pursued by the feds for (hark!) publishing source code for an encryption system. All that did was make a hero out of him and publicize the software. I suspect someone snooping on the network connection of a Zfone user might be able to tell when calls were being made and perhaps determine to whom the call was made, assuming SIP traffic can be recognized and the addresses of the two parties identified. But the contents of the call are going to be very hard to crack. Of course, such calls must stay all VOIP-to-VOIP. Calls using the PSTN (Public Switched Telephone Network) would be easily tappable through conventional means. Click here to read about network providers attempts to fight the FCC over VOIP wiretapping. So if Im a criminal (or an innocent person) attempting to keep my calls private, I will have no trouble doing so, so long as the other party and I agree to use the same or compatible software and keep the call on the Internet. On the other hand, people not trying to conceal themselves will probably be as "tappable" as they were on the PSTN. I guess criminals do mistakenly make calls on insecure lines at times. Shouldnt law enforcement, with a valid warrant, be able to access such calls? The argument against it is an argument against conventional phone-tapping as well, and thats an overreaction. Clearly Zfone makes it possible to avoid such surveillance, if youre careful, but I think its necessary that the option exist. Just because law enforcement has a legitimate interest in monitoring some calls doesnt mean that users have no interest in their own privacy. It does make the job of law enforcement harder. Welcome to the 21st century. Security Center Editor Larry Seltzer has worked in and written about the computer industry since 1983. He can be reached at larryseltzer@ziffdavis.com. Check out eWEEK.coms for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at eWEEK.com Security Center Editor Larry Seltzers Weblog.

Larry Seltzer has been writing software for and English about computers ever since—,much to his own amazement—,he graduated from the University of Pennsylvania in 1983.

He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find absolutely no hits on any of these +products on Google.) His work at Desktop Software included programming the UCSD p-System, a virtual machine-based operating system with portable binaries that pre-dated Java by more than 10 years.

For several years, he wrote corporate software for Mathematica Policy Research (they're still in business!) and Chase Econometrics (not so lucky) before being forcibly thrown into the consulting market. He bummed around the Philadelphia consulting and contract-programming scenes for a year or two before taking a job at NSTL (National Software Testing Labs) developing product tests and managing contract testing for the computer industry, governments and publication.

In 1991 Larry moved to Massachusetts to become Technical Director of PC Week Labs (now eWeek Labs). He moved within Ziff Davis to New York in 1994 to run testing at Windows Sources. In 1995, he became Technical Director for Internet product testing at PC Magazine and stayed there till 1998.

Since then, he has been writing for numerous other publications, including Fortune Small Business, Windows 2000 Magazine (now Windows and .NET Magazine), ZDNet and Sam Whitmore's Media Survey.

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