Mathematical proof could lead to unbreakable code

Thursday, March 1st 2001, 12:00 am
By: News On 6

BOSTON (AP) _ Cryptology experts are abuzz over a Harvard professor's claim that he can make an unbreakable code that can be used over and over again.

Computer science professor Michael Rabin, with the help of doctoral student Yanzhong Ding, developed a mathematical proof that experts say could be used to make a code indecipherable even by the most powerful computers.

``We are doing something that is seemingly impossible, and that is, of course, extremely exciting,'' Rabin said Wednesday.

Rabin's method uses a stream of randomly generated characters that can be decoded with a mathematical formula. Once the message is decoded, the stream disappears, leaving nothing for hackers to decipher, Rabin said. The key can be reused on a different message.

``Unbreakable codes'' have been created before, but they were for one-time-use only, experts say.

Rabin said he is not yet planning to commercialize the system. If he does, it could be used by corporations, governments or any group that wanted to keep top-secret information secure.

Richard Lipton, a computer science professor at Princeton University, said he has seen the formula and is convinced it could work. Lipton said Rabin's most significant achievement was proving his ideas mathematically.

``Though the idea seems obvious, the math behind it is quite hard,'' he said.

Another professor, however, said by e-mail that he has reservations.

``There are a few places in which I would need to investigate much more before I would accept these claims,'' said Richard Kaye, a mathematics professor at the University of Birmingham in England. Kaye made headlines last fall when he argued that playing the computer game Minesweeper could lead to a way of cracking codes efficiently.

Even supporters such as Lipton do not believe Rabin's work will create a code that is unbreakable forever. Someday, they say, computers will be able to store enough information to render Rabin's code vulnerable.

``It becomes an arms race, just as it is with virus detection or missile defense,'' Lipton said.