Hackers Eavesdrop On Quantum Crypto With Lasers

Martin Hellman writes "According to an article in Nature magazine, quantum hackers have performed the first 'invisible' attack on two commercial quantum cryptographic systems. By using lasers on the systems — which use quantum states of light to encrypt information for transmission —' they have fully cracked their encryption keys, yet left no trace of the hack.'"

Comments

Re:pwned

[neumayr]

Not really. From the article:

"We have exploited a purely technological loophole that turns a quantum cryptographic system into a classical system, without anyone noticing," says Makarov.

So OK...

[hyades1]

...maybe they've cracked it in this universe, but what about all the others?

Re:Lessons

[neumayr]

The underlying principle still is valid, those people exploited a technical loophole - in a process that's part of

[..] years of dedicated effort in an open environment.

Re:pwned

[Unipuma]

If you read the article, you'll notice that the 'hack' is a classic man in the middle attack, and the receiving end can receive both classic and quantum messages. The man in the middle (after reading the quantum message) passes it on as a classic message, and the receiving device does not give a warning that the message received is a classic message, instead of a quantum message.

So it's really an design error on the device side, not a true hack in that quantum states were undisturbed regardless of reading them.

Re:pwned

[PseudonymousBraveguy]

No, it IS a huge problem. If you turn a quantum computing system into a classical system, you basically revert it to sending the key in plaintext. While it does not break the theory of quantum encryption, breaking all (commonly) available implementations of quantum crypto should be enough to be qualified as "huge kick in the balls".

Re:It seems that you could detect this

[PseudonymousBraveguy]

Yes, and if I understand the article correctly, the manufacturers developped a patch to fix the hole.

However, the hack shows (once again), that a system may be secure in theory, but actual implementations of that system may, and will, have bugs that render them insecure. This negates one of the most strong arguments for quantum crypto, i.e. the "proveable" security. If that argument does not hold, you could as well use any common "classical" key exchange algorithm, which also delivers "good, but not 100%" practical security, does not need fixed point-to-point fiber and expensive equipment, and is probably much better tested than the quantum systems.

a kick in the balls

[davidwr]

A kick in the balls (breaking all current implementations) is not the same as cutting them out and mounting them in a trophy case (proving there can be no secure implementation).

Either one hurts though.

Why 'hackers' and not 'researchers'?

[RevWaldo]

Even respecting the working-all-day-and-night-in-the-basement-computer-lab origin of the term, using 'hacker' in the article seems like a blatant attempt to jazz it up, making it at first glance seem to be more about something akin to bank heist than a story about funded researches working in a university lab trying to find flaws in a security system, with the manufacturer's full approval to boot.

.

Re:pwned

[maxwell demon]

Well, there are several points here:

• Every cryptographic security is only up to possible bugs in the implementation (remember the Debian ssh problem?), so exactly 100% security is impossible. However, one difference betweeen the classical and quantum case is that in the quantum case any possible exploit has to be "online" (i.e. you have to actually intercept the actual sent message and manage to manipulate the receiving system), while for classical key exchange the breaking can also be after the fact (i.e. if all you want is the exchanged information, you can passively record all data and then try to break it afterwards). This means that
  1. all communications performed before that exploit was found remains secure (unlike classical protocols where you only need the recorded data to apply any exploit), and
  2. since the attacker has to manipulate the systems during operation, as soon the exploit is known you can take additional measures in order to detect it (e.g. in this case, I think it should be quite easy to detect a relatively strong laser which is continuously shining at the receiving device), thus detecting whether someone tries to exploit it (unlike classical systems, where you have no clue if someone tries to attack your cryptographic system). That is, instead of replacing your whole cryptographic infrastructure (which may be expensive), you can simply add detectors for the manipulation needed for the exploit, so that you only transmit confidential information in case the exploit isn't applied.
• As the article mentions, the commercial systems add the quantum cryptography on top of the classical cryptography. So if the quantum cryptography is broken, you still have the security of the classical system. On the other hand, if the classical system used is broken (be it because the underlying cryptographic scheme is broken, or be it by exploiting a bug in the specific implementation) then you still have the security of the quantum cryptography.