Harvard prof in uncrackable crypto claim

A Harvard computer science professor says he has developed a provably unbreakable encryption technique, with a key based on a stream of random numbers.

The idea of a disposable key is not new, and was used to great effect during World War II, but according to Dr Michael Rabin, this is the first time it has been made to work electronically. Rabin said that he could also provide mathematical proof of its security.

"This is the first provably unbreakable code that is really efficient," Rabin told Cryptome. "We have proved that the adversary is helpless."

The key is taken from a continuously generated string of random numbers. Somehow, the sender and recipient agree on which section of the number string they will use to encipher and then decipher the message.

The two parties could use any publicly available encryption system to decide on the start time, Rabin says. If someone were to intercept this communication, by the time it was decrypted, the sequence would already have started and the information would be useless.

Then, because the numbers are not stored anywhere on either machine, there is no way either party could be forced to hand over the key.

However, not everyone is convinced that having an uncrackable code is a guarantee of security.

Dr Robert Morris, a former NSA cryptographer, said that there were other methods of revealing the contents of a secure message. "You can still get the message, but maybe not by cryptanalysis. If you're in this business, you go after a reasonably cheap, reliable method. It may be one of the three Bs: burglary, bribery or blackmail," he said. ®

Related Link

The full story and a discussion of the method is over at Cryptome.