By John Schwartz
One of the most common systems for scrambling sensitive digital data has been defeated in a 56-hour attack by a custom-built computer costing just $250,000.
Privacy advocates said the feat, part of a contest sponsored by a computer security company, casts doubt on the strength of a standard encryption system used by private business and government, and also undercuts the U.S. policy of trying to restrict the export of stronger forms of encryption.
Encryption, the science of scrambling information, is an essential tool for business and privacy-minded people who communicate via computers. The Commerce Department has set limits on the strength of encryption systems that can be licensed for export in the hopes of keeping such technology from criminals and terrorists, who might use it to hide their plans and misdeeds behind a cloak of unbreakable codes.
That policy has been criticized by cryptographers and privacy advocates, who say that the Data Encryption Standards (DES) systems allowed for export are too weak to offer adequate security and hurt American companies.
DES had been cracked before but after much greater effort and time during a previous cryptography contest sponsored by RSA Data Security Inc., a Silicon Valley company that makes powerful cryptography systems. That successful 1997 attack involved a network of thousands of networked computers crunching away at the problem for five months. A second attack earlier this year achieved the same goal in 39 days.
A measure of strength of cryptographic systems is the length of the "key," or chunk of code used to unscramble data. The contest winner announced yesterday cracked a form of DES using a 56-bit key the same key length found in systems that the government does allow for export as long as such systems will eventually include a back door for law enforcement.
"This is finally public proof that DES is totally inadequate, and government proposals that threaten key length are seriously threatening privacy and security on the Net," said David Banisar of the Electronic Privacy Information Center, a Washington-based policy group.
Law enforcement and national security officials have repeatedly told lawmakers that DES is a strong cryptographic system that would take millions of dollars worth of supercomputing power and huge amounts of time to crack. The fact that a relatively inexpensive computer could crack DES suggests that those agencies also have the capacity or should, said Barry Steinhardt, executive director of the Electronic Frontier Foundation (EFF), the California-based high-tech policy group that created the cracking computer.
"They either misled the Congress or they're not doing their jobs," Steinhardt said.
A spokeswoman for the Commerce Department, which regulates cryptography exports, would not comment. Calls to the National Security Agency were not returned.
The EFF effort was headed by John Gilmore, a civil liberties activist, and cryptographer Paul Kocher. The machine itself was a high-end personal computer connected to an array of specially designed chips that was able to search through 88 billion keys per second to find the one that worked.
EFF and O'Reilly and Associates announced the publication of a new book describing the new machine and the software it used. The group is not trying to aid criminals or hackers, Steinhardt said. Instead, the group hopes "to bring honesty to the encryption debate" by revealing flaws in the government's policies.
"Our long-term goal is to reverse the export policy that limits the export of strong cryptography," Steinhardt said.
Encryption systems can be strengthened by using longer keys, or by scrambling data repeatedly; cryptographers have not yet cracked a triple-scrambled DES message.