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| Privacy Guru Zimmerman Locks Down VOIP |
| 2005-07-28 |
| First there was PGP e-mail. Then there was PGPfone for modems. Now Phil Zimmermann, creator of the wildly popular Pretty Good Privacy e-mail encryption program, is debuting his new project, which he hopes will do for internet phone calls what PGP did for e-mail. Zimmermann has developed a prototype program for encrypting voice over internet protocol, or VOIP, which he will announce at the BlackHat security conference in Las Vegas this week. Like PGP and PGPfone, which he created as human rights tools for people around the world to communicate without fear of government eavesdropping, Zimmermann hopes his new program will restore some of the civil liberties that have been lost in recent years and help businesses shield themselves against corporate espionage. VOIP, or internet telephony, allows people to speak to each other through their computers using a microphone or phone. But because VOIP uses broadband networks to transmit calls, conversations are vulnerable to eavesdropping in the same way that e-mail and other internet traffic is open to snoops. Attackers can also hijack calls and reroute them to a different number. Few people consider these risks, however, when they switch to VOIP. "Years ago, people kind of stumbled into e-mail without really thinking about security," Zimmermann said. "I think that what's happening today with VOIP is that we're kind of stumbling into it (as well) without thinking about security." People don't think about it, he said, because they're used to phone calls being secure on the regular phone system -- known as the Public Switched Telephone Network. "The PSTN is like a well-manicured neighborhood, (while) the internet is like a crime-ridden slum," Zimmermann said. "To move all of our phone calls from the PSTN to the internet seems foolish without protecting it." Interest in VOIP is growing rapidly because the user pays less for the service and pays no long-distance toll charges. Some services are free. According to one recent survey, 11 million people worldwide use a subscription VOIP service, compared to only 5 million in 2004, and at least another 35 million use free VOIP services. That leaves a lot of people potentially open to eavesdropping. It's not as easy to eavesdrop on VOIP as it is to intercept and read e-mail. Phone conversations aren't stored or backed up where an attacker can access them, so the conversations have to be captured as they occur. But a program available for free on the internet already allows intruders to do just that. Using the tool, someone with access to a local VOIP network could capture traffic, convert it to an audio file and replay the voice conversation. The program is called Voice Over Misconfigured Internet Telephones, a name clearly chosen for its catchy acronym -- VOMIT. Bruce Schneier, chief technology officer of Counterpane Internet Security and author of the Crypto-Gram newsletter, said that the need for VOIP encryption is a given. "If you're concerned about eavesdropping, then encryption is how you defend against it," he said. "And it's not that hard to do. It's just a matter of writing the code." But David Endler, chairman of the VOIP Security Alliance industry group and director of security research at TippingPoint, said a protocol for encrypting and protecting VOIP data already exists and companies are starting to make VOIP phones that support the protocol. But he said that people typically don't enable the encryption option. "Probably because we're not seeing attacks yet," he said. He said most users are less concerned with eavesdropping than with having VOIP service that provides the same quality and reliability that they expect from regular phone service. "Some people can see clearly that there's a need for this, and others wonder if anyone cares about protecting phone calls," Zimmermann said. "But those are the same people who wondered why anyone would want to protect e-mail. I think as people gain experience with VOIP they're going to have a great appreciation for the need to come up with extra measures to protect it." Endler also said that companies using VOIP are reluctant to implement encryption because of the overhead involved in managing the public key infrastructure, or PKI. "You have to be able to store a key on most of these end points," he said. PKI requires two keys for encryption: a public key that a user gives to anyone who wishes to communicate with him or her, and a private key, which decrypts messages that the user receives. That won't be a problem with Zimmermann's system, which doesn't use PKI. Zimmermann said PKI is unnecessarily complex for VOIP. "There's no need to centrally manage public key infrastructure to make a phone call, in my view," he said. He won't elaborate on how his system works but is preparing a protocol document that will describe it in detail, which he'll post on the internet when the program is ready. The program is currently only a working prototype and still has non-security bugs that need to be worked out. For example, sometimes the program fails to hang up after a call, forcing the user to exit the program to end the call. It's designed for a Mac, but will be adapted for PCs before Zimmermann makes it available for download. He's looking for investors to back a startup company that will support the product and oversee its distribution. Zimmermann envisions it both as an add-on for manufacturers to put into VOIP phones and as a software client that users can install on their laptop to use when they don't have a VOIP phone with them. Both parties in a conversation will need to have the software on their phone or computer. If only one person has it, the call will still go through but it won't be encrypted... |
| Posted by:Anonymoose |