CODE-makers could be on the verge of winning their ancient arms race with code-breakers.
After 20 years of research, an encryption process is emerging that is considered unbreakable because it employs the mind-blowing laws of quantum physics.
This month, a small startup called MagiQ Technologies began selling what appears to be the first commercially available system that uses individual photons to transfer the numeric keys that are widely used to encode and read secret documents.
Photons, discrete particles of energy, are so sensitive that if anyone tries to spy on their travel from one point to another, their behavior will change, tipping off the sender and recipient and invalidating the stolen code.
"There are really no ways (of) cracking this code," said Lov Grover, a quantum computing researcher at Bell Laboratories who is not involved with MagiQ.
Called Navajo - a nod to the American Indian code specialists of World War II - MagiQ's system consists of 19-inch black boxes that generate and read the signals over a fibre-optic line.
MagiQ (pronounced "magic," with the "Q" for "quantum") expects that with a cost of $US50,000 to $US100,000, Navajo will appeal to banks, insurers, government agencies, pharmaceutical companies and other organizations that transmit sensitive information.
"We think this is going to have a huge, positive impact on the world," said Bob Gelfond, MagiQ's founder and chief executive.
Encryption schemes commonly used now are considered safe, though they theoretically could be broken someday.
But even before that day arrives, Gelfond believes quantum encryption is superior in one important way. In some super-high-security settings, people sharing passwords and other information must have the same key, a massive string of digits used to encode data. Sometimes the keys will be transferred by imperfect means - via courier or special software. They are not changed very often and can be susceptible to interception.
"Even if you have the perfect encryption algorithm, if someone gets your key, you're in trouble," Gelfond said.
The Navajo system not only transmits the keys on snoop-proof photons, it also changes them 10 times a second. "Even if somebody could get a copy of the key, it wouldn't do them any good," Gelfond said.
Of course, unbreakable codes would neutralize the ability of intelligence agents to intercept and read messages. That would necessitate greater reliance on human intelligence.
So does the world's foremost code-making and code-breaking organization, the U.S. National Security Agency, worry about the spread of quantum encryption? Better yet, is the NSA using the technology itself? Like most things about the NSA, those answers remain secret.
MagiQ is seeking the government's approval to sell Navajo boxes overseas. Gelfond hopes officials have realized - after trying and failing to restrict encryption exports in the 1990s - that there's little point in trying to "put the genie back in the bottle" once encryption methods have been invented. After all, he said, researchers in China are known to have experimented with quantum encryption.
At least one other company, Switzerland-based id Quantique SA, has produced a system similar to Navajo, though that remains in pilot phase.
Meanwhile, other organizations are exploring different ways of using subatomic particles as code carriers. QinetiQ, the commercial arm of Britain's defense research agency, and the national lab in Los Alamos, N.M., have experimented with transmitting quantum keys through the air rather than over fiber-optic lines.
Researchers at IBM, where quantum encryption was first demonstrated in the 1980s, are exploring ways to shrink quantum systems so they can plug more efficiently into existing computing and communications networks.
In any incarnation, quantum encryption employs one of the defining discoveries of physics: Heisenberg's Uncertainty Principle, which says subatomic particles exist in multiple possible states at once, however hard as that may be to imagine, until something interacts with them.
When one Navajo box sends out a code key, it imparts certain measurable characteristics to photons that travel through the fiber-optic line. When the second Navajo box measures those characteristics, that mere act throws off other characteristics - but the Navajo boxes confer with each other after the transmission is complete and sort it all out. The boxes can be up to 70 miles apart, after which additional boxes are needed as relays.
"It's intriguing," said James Capuano, operations director for NEON Communications, a Massachusetts-based telecom carrier that has tested Navajo boxes on its network and now is exploring whether its customers would pay extra to use them. "It's a very simple product to deploy."
It's also just the first step on a deeper quest to use quantum physics.
Within a few decades, scientists hope to use the multiple possible states and interactions of subatomic particles as replacements for the binary 0s and 1s used in computing today. A quantum computer, if it comes to pass, would be able to perform several complex calculations simultaneously, making it exponentially more powerful than today's supercomputers.
Researchers have performed simple calculations with a few particles but are a long way from being able to replicate that in a large quantum soup in a controllable and consistent manner.
In the 1990s, landmark research by Peter Shor of AT&T Labs showed that quantum computers would be powerful enough to crack any code in use today - except ones generated through quantum cryptography.
So at long last, code writers might be done fighting to stay ahead of code breakers.
"We'll stop this race," said Gregoire Ribordy, a founder of id Quantique. "We'd like to have a system that's forever secure."
