During World War II, the Nazis used a famously complex code machine to communicate military orders, assuming that no one would go through the effort needed to break its formidable encryption. The typewriter-like Enigma was a marvel of engineering, full of gears, dials, lights, keys, and a plugboard. But despite its clever design, the cipher was eventually broken by computers; because it relied on pseudo-random mechanical encryption, there were only a finite number of patterns possible. By the end of the war, British and American intelligence services were routinely decoding and reading intercepted Nazi messages.
Now Seth Lloyd, a researcher at MIT, has demonstrated that by exploiting the quirks of quantum physics, it is possible to build an encryption machine that is truly unbreakable.
"The funny thing about quantum mechanics is when you measure something, you mess it up," Lloyd tells Popular Science. Lloyd's theoretical quantum cryptography machine works like this: When an eavesdropper tries to make a measurement that would help him or her crack the code, the act of making the measurement disrupts what he or she is trying to measure. Tricky, right?
A peculiarity of quantum physics turns photons, fired one at a time, into a secure lock. The observer effect states that an observed photon behaves differently than an unobserved one. If a code relies on patterns of photons, the key to breaking it is therefore unobservable. This protects the whole message and makes it impossible for a third party to eavesdrop on the conversation, because the very act of eavesdropping changes the code. The is called quantum data locking, and it is at the core of Lloyd's theoretical quantum enigma machine.
The intended recipient of a message is able to decode the transmission because he or she would already have prior knowledge of the message's quantum state.
There is one weak spot: If the third party intercepting the message has already received a decoded partial fragment of the message (and therefore knows how to measure the incoming message) the key securing the rest of the message can be broken, and then the whole message can be deciphered. (This, of course, would require obtaining a partial message through other means.)
The paper is titled "Quantum enigma machines."
i remember that enigma machine ... the british stole it from the germans and cracked the codes.
i think the movie of the event was U-571 ... although they replaced the historically correct British, with the hot ticket selling Americans.
damn hollywood treatment. sigh ... it would make you think that the Iranian hostage situation was planned exclusively by the Americans, and not by the Historically correct Canadians.
But who wants to sit through the 'Canadian Caper' when they can sit through Argo ...
i'm gonna stop complaining now. ;)
but seriously, wicked tech. good article.
I read this article and all I have to say is: what?
Every encrypted msg is meant to be decrypted by something. That means I don't need to cipher your msg. I could simply entangle the source, or the target, and read your msg at either end. I don't even have to entangle the msg target or transmission either. I could simply entangle the photons coming from your screen and read what you read. Entanglement is the thing that makes full security of quantum cryptography both possible and vulnerable. The advancements of changing the energy states of the Atoms/Photons/Qubits that are containing your messages will be the key to making this technology as truly safe as your article claims. True that QC is capable of creating secure messages but it doesn't stop someone from Eaves Dropping the msg, though they may not be able to cipher it, and it doesn't stop someone from entangling your msg source, target or peripherals used to visualize said msg. Therefore, it's not safe. You could entangle the entire room that houses the computers your msg was sent from and I assure you that the msg can be observed by a 3rd party. Today we entangle Qubits, of varying types... tomorrow, entanglement via dissipation (not coherence) we entangle rooms worth of atoms.
A good classical comparison would be... why catch the email that you are sending to someone when I could capture your whole network that your sending it from? Then I have all your data including the message. No one is trying to brute force crack your QC message and that is the "case" that most present when they speak of an unobservable message. We are talking about the replacement for RSA (prime number) encryption that is the standard today. The work it would take to bust a long prime number WAS difficult. It's not now. Make no mistake though, in the very near future entanglement will be able to capture it all. Period. QC and quantum computing are so new. Any breakthrough in this field today is premature for the new technology. It is naive to rely on such a new technology as your security of the future. Especially when such loopholes exist in the physics of said new technology. We should wait a few more years at least before considering this a standard for secure communication.
"Do not try and bend the spoon. That is impossible. Only try and realize the truth - there is no spoon."