That test put the lie to claims by U.S. Commerce Department, law enforcement and national security officials who repeatedly insisted to lawmakers that DES could withstand any but the most sophisticated supercomputing hacker attempts to break it.
Then, early this year, a second attack on DES succeeded after 39 days.
And this summer, one $250,000 custom-built computer cracked the code in just 56 hours.
That computer was built by the Electronic Frontier Foundation, a high-tech policy group based in California. EFF entered the machine in a contest sponsored by RSA Data Security Inc., a Silicon Valley company that makes cryptography programs. The DES system it cracked was based on a 56-bit key-the length of code used to unscramble the encrypted data-that the U.S. government allows software makers to export as long as they promise to include a law-enforcement "back door" at some point in the future. The computer sorted 88 billion keys per second for more than two days to find the one 56-bit key that worked.
One way to strengthen DES resistance to code-breaking attempts is to lengthen the key, says Greg Garcia, coalition manager at Americans for Computer Privacy, a Washington, D.C.-based industry and policy group. Cryptographers estimate that "if you took a platoon of supercomputers and set them to break a 128-bit encryption, the time it would take them to run the number of combinations available would be something like 6.3 trillion times the age of the universe," Garcia says.
Of course, that's with today's computing power. In a few years, 256-bit keys may be needed to keep secrets. But that's not the main thing Garcia and the 90 or so software-makers in his group are worried about.
Rather, it's the insistence of the Clinton administration and the FBI that cryptographers imbed that "back door" into every encryption system they write. Law-enforcement and national-security officials say they need that back door to monitor the computer and online activities of criminals and terrorists. But Garcia and his group argue that "what you're doing is setting up a whole infrastructural vulnerability."
"This is going to affect everybody," Garcia says, "whether or not you use a computer." Everything from municipal power and water systems to corporate bank accounts and proprietary business information relies on some form of encryption to secure it from prying eyes. "Think of any scenario where you want to protect information, and somebody else wants to get it." Yet software manufacturers will have to incorporate "key recovery" routines to open a back door into protected system, if the FBI proposal is not thwarted in Congress.
Two bills-H.R. 695, the Security and Freedom through Encryption Act, and S. 2067, the so-called "E-Privacy" Act-are pending in Congress to address "key recovery" and close the back door. "We support both these bills very strongly," Garcia says. As a compromise, ACP proposed setting up a NET Center to make industry-encryption experts available to law enforcement for emergency code-breaking. The Clinton administration has said it is considering the idea and may announce an agreement this fall.
As long as the FBI resists attempts to close the cryptographic back door on new encryption software, Garcia says no business's information will be completely secure. And the $2 billion-a-year U.S. encryption software industry will be vulnerable to competition from manufacturers, such as Germany, where key recovery back doors are not required.