Single-Photon LED: Key To Uncrackable Encryption?

nut writes: "The BBC are carrying this story of new type of LED so precise that it can emit just one photon of light each time it is switched on. It has been developed by scientists from Toshiba Research Limited and the University of Cambridge. It is described in the journal Science, although I can find no mention of it on their website. One of the applications of this is supposedly uncrackable encryption, due to the law of indeterminacy. This application is described fully in 'The Code Book', by Simon Singh, although the method was only theoretical at the time the book was first published."

Comments

NOT Uncrackable

[MikeyNg]

The application refers to its use in quantum cryptography. It doesn't render the encryption process uncrackable, but makes it able to detect that someone is eavesdropping and/or has broken the encryption. With current methods, you can't tell if someone has broken your key and read your message. Using quantum cryptography, you can tell when someone has read your message.

(It all goes along the lines of you can't observe something without changing it. If someone along the way intercepts the message and observes it, they will change the message and you can detect THAT on the other end.)

Re:NOT Uncrackable

[MWright]

It is uncrackable.

It does detect if someone is eavesdropping, but it detects it as the key is generated, not when you send the message. Your post implies that you send the message, and can detect if anyone eavesdrops... this is not the case. Two parties use these quantum effects to generate random numbers... they can detect if someone is eavesdropping on this; if someone is, they don't have to use that key (even if someone does try to eavesdrop, it won't work, by the way). Once they have this key, they can use it in One-Time-Pad encryption, which is also uncrackable (see a text on information theory for an explanation about why OTPs are uncrackable).

Not only theoretical.

[Mr_Icon]

This application is described fully in 'The Code Book', by Simon Singh, although the method was only theoretical at the time the book was first published."

Uhm... I believe this is wrong. The book was issued in 1999, and it contains this sentence in chapter 8:

In 1995, researchers at the University of Geneva succeeded in implementing quantum cryptography in an optic fiber that stretched 23 km from Geneva to the town of Nyon.

Moreover, one paragraph further we see:

More recently, a group of scientists at Los Alamos National Laboratory in New Mexico has once again begun to experiment with quantum cryptography in the air. Their ultimate aim is to create a quantum cryptographic system that can operate via satellites. If this could be achieved, it would enable absolutely secure global communication. So far the Los Alamos group has succeeded in transmitting a quantum key through air over a distance of 1 km.

One of us is wrong -- either I'm reading this from an edited version of "the Code Book", although nowhere does it say "second edition", or the original poster needs to re-check his facts.