I first downloaded Pretty Good Privacy a couple of years ago, at the request of an interview subject. He was nervous about discussing his drug use through unprotected e-mail, and my willingness to use PGP reassured him not only that he would be safe from eavesdroppers but that he could trust me to take his privacy concerns seriously.
It was a small illustration of encryption's power, but it brought home to me what a godsend this kind of readily available, easily used software must be to dissidents who risk prison by sharing unauthorized information or expressing forbidden opinions. Phil Zimmermann had such people in mind when he created PGP a decade ago and risked prison by posting it online.
At the time, the U.S. government considered strong encryption software a "munition," and by making it available to human rights activists around the world Zimmermann was arguably violating a federal ban on the export of such weapons. Some politicians are trying to revive this sinister view of encryption in the wake of last month's terrorist attacks.
In a floor speech a week after hijacked airplanes collided with the Pentagon and the World Trade Center, Sen. Judd Gregg, R-N.H., worried aloud about "somebody out there using encryption technology for the purposes of pursuing a terrorist act in the United States." He declared, "There is no excuse for anybody to be underwriting that type of activity in our country."
To prevent terrorists from shielding their communications, Gregg wants to make all producers of encryption systems design their products so the government can read the messages they generate. The surveillance would be "judicially controlled" to make sure it "simply gets at the bad guys."
Gregg's opposition to strong encryption is echoed in some surprising quarters. Boston Globe columnist Cathy Young, a colleague of mine at Reason magazine, has confessed that "the idea of people being able to encrypt electronic communications so that they are beyond surveillance" has always seemed "scary" to her, "precisely because of the threat of terrorism."
This is like saying that computers or telephones or airplanes or box cutters are scary. Any technology can be used for good or ill. The question is whether the potential for evil justifies restrictions on legitimate uses.
As more than one critic has pointed out, the arguments against strong encryption could also be used against strong locks, since criminals tend to hatch their plans behind closed doors. That doesn't mean all of us should make extra sets of house keys for the police in case they need to search our homes.
We have been down this road before with various proposals during the 1990s for "key recovery" arrangements through which the authorities could break otherwise unbreakable codes. Now as then, the most decisive argument against encryption controls is that they wouldn't work because PGP-like software is already available from a variety of sources.
Does Sen. Gregg plan to come to my house and erase my copy of PGP? If not, how can he possibly hope to stop terrorists, who are much more highly motivated than I am to shield their communications, from obtaining and using such software?
The attempt to do so would weaken security rather than enhancing it. A 1998 report from a panel of distinguished cryptographers and computer scientists concluded that "there are compelling reasons to believe that, given the state of the art in cryptology and secure systems engineering, government-access key recovery is not compatible with large scale, economical, secure cryptographic systems." A member of the panel, Matt Blaze, recently told The Washington Post, "I am extremely doubtful that this could be done without weakening computer systems, and the costs would be absolutely staggering."
In addition to the bugs introduced by added complexity, keeping extra copies of the keys used to decode messages would create tempting targets for thieves. The keys could also be compromised by incompetent or corrupt officials charged with protecting them.
Misuse of official records is not exactly unheard of in this country, and the problem would be magnified if every unsavory regime that has enlisted in the war on terrorism were to be trusted with the keys to its citizens' e-mail. For the dissidents Phil Zimmermann is rightly proud of helping, the whole point of encryption is to guard against official surveillance. If Gregg's vision were ever realized, they would once again have to watch what they say.