I must say, it doesn't look like the N.S.A. is going to stop warrantless intercepts of phone calls and e-mails anytime soon. And despite the Bush administrations insistence that this is a "Terrorist Surveillance Program" and that the program focuses on people who are communicating with known terrorists, it is clear that it is mostly innocent Americans who are being caught in the dragnet.
According to this past Sunday's
Washington Post, less than 10 U.S. citizens or residents per year who were monitored by the program have been suspicious enough for the Federal government to obtain a warrant to intercept their domestic phone calls. The NY Times
reported last month that the FBI has found the leads generated by the program to be generally useless in the War on Terror. "We'd chase a number, find it's a school teacher with no indication they've ever been involved in international terrorism - case closed," said one former FBI official, who was aware of the program and the data it generated for the bureau. "After you get a thousand numbers and not one is turning up anything, you get some frustration." The situation is so bad that in the FBI, the N.S.A. material continued to be viewed as a waste of time. One official who supervised field agents told the Times that a new batch of N.S.A. leads lead his men to joke about more "calls to Pizza Hut".
It is clear to me that the N.S.A. intercept program is both illegal and ineffective, and that eventually, it will be stopped for those reasons. But although I'm neither a school teacher nor a Pizza Hut employee nor a terrorist, I still don't cotton to the idea of the N.S.A. listening in on me in the meanwhile. So, for my benefit and yours, here is a simple guide to a few things you can do to prevent the N.S.A. from being able to monitor your calls and emails.
Note: None of the methods I will suggest are illegal. No information will be provided here that isn't readily available someplace else.
First of all, to get an idea of what we are talking about, let's begin with the two major forms of phone intercepts. The more familiar kind, to anyone who watches police shows, is called a loop-extender tap. In a loop-extender tap, the target telephone line is tapped in the field with a loop-extender device, which relays the signals and content to the law enforcement agency over its own telephone line. These systems can only intercept wireline (traditional non-cellular) telephone calls, and are largely obsolete. However, many law-enforcement agencies still have this equipment in use.
The loop-extender taps have been largely replaced with CALEA taps (which stands for the 1994 Communications Assistance for Law Enforcement Act). CALEA taps act on the legislation which mandated that there be a standard interface between telephone service providers (including wireline and cellular services) and agencies that perform wiretaps. In CALEA taps, the telephone company decodes the signaling information and, when a full audio intercept is authorized, separates out the call audio to its own channel. The law enforcement agency connects to the telephone company through the standard interface, the signaling information (including dialed digits, on-/off-hook status, and so on) and call audio are sent to the agency over separate channels. This is of special significance: since the phone companies have provided government agencies direct access to the switches, there is no telling how many calls are being pulled via that interface.
One method of defeating loop-extender taps is pretty simple. Telephones not in use generate a sound called a C-Tone, which indicates that the line is idle. Most intercept systems use this C-Tone to signal when a phone is in use and to begin recording. Some military phones have a C-Tone button that can be used to generate a false C-Tone; you can find those often on eBay. You can also download software that can be used to generate a C-Tone. In all cases, some modification may be needed to reduce the volume of the C-Tone so that it can be spoken over. This excellent site has a sample mp3 of a phone conversation with a C-Tone generated intercept failure, as well as the entire conversation recorded with the C-Tone bursts included.
In an excellent piece in Slate, a test performed by University of Pennsylvania Professor Matt Blaze shows that even CALEA systems still have a surprising vulnerability to C-Tone interference. Mr. Blaze believes that the Department of Justice may have asked to have the C-Tone feature included in new systems so that they would remain compatible with older systems. For more information, you can see articles here, here, and here. Anyone interested in Matt Blaze's study in full can see it here courtesy of the magazine Security & Privacy.
If there is continued interest, I'll try to provide further work on legal methods you can take to put your privacy into your own hands. And in addition, I'd be interested in any links or suggestions of where to find more resources in this area.