Quantum Cryptography to the Rescue

Cryptographic systems can be cracked. And people make mistakes. Take those two factors out of the equation, and you have quantum cryptography and a new way to protect your data.

May 01, 2005 — CSO — Most modern crypto-graphic techniques ultimately stand on some pretty weak assumptions. The popular RSA public-key encryption algorithm gets its strength from the difficulty of factoring large numbers. But if a government or criminal organization has a mathematician who figures out how to factor large numbers quickly and efficiently, then much of the information that's encrypted on today's Internetand almost everywhere elsewill suddenly become vulnerable to eavesdropping and wiretapping. CSOs need to understand that today's cryptographic systems, which protect information moving over networks, are vulnerable to human error and attack. But there's something you can do about it. A new kind of cryptography based on quantum physics is now ready for serious consideration.

It turns out that there are only two encryption techniques that are provably unbreakable. The first technique, called a one-time pad, uses an encryption key that is as long as the message you are trying to encrypt. Such systems don't work well in practice: It's just too easy to make a mistake and reuse a part of the encryption key. The key also has to be completely random and you need to distribute the key, which you can do only with a physical courier. Make sure he has a gun.

The second kind of secure encryption is based on quantum physics. Called quantum cryptography, such systems have been the gist of academic conferences and physics journals since the basic scheme was invented by IBM in 1984. Quantum cryptography has also been a running joke among some security pundits, who say the system is so secure nobody needs itconventional cryptography is strong enough because cryptography is never the weakest link in the chain.

But wait! Now there's a real-live quantum cryptography system that you can purchase for about $70,000. It provides absolutely unbreakable security for any fiber link you wantprovided that the link you need to secure is no more than 120 kilometers longand the system is astoundingly easy to set up and administer. That's because unlike virtual private networks, or VPNs, which are based on conventional cryptography, quantum cryptography doesn't require you to create keys and keep them secret, and there's no need to distribute certificates. The system makes its own keys automatically. They're absolutely random, and they change a dozen times every second.

I recently had a chance to visit the labs of MagiQ Technologies, the company that's commercializing this technology. MagiQ's system uses quantum cryptography to transfer encryption keys from a sender, which the company affectionately calls "Alice," to a receiver, which the company calls "Bob." Once Alice and Bob have used quantum cryptography to get that secret encryption key across the link, those keys are used to encrypt standard TCP/IP or UDP/IP packets sent across a single-mode optical fiber. MagiQ calls this approach quantum key distribution (QKD), and they call the resulting VPN a quantum private network, or QPN.