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:So OK...

[thijsh]

I would take a look, but I'm too afraid I'll kill the cat... And you all know how much Slashdot-geeks love that inter-dimensional pussy.

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.

not really that bad

[mogness]

The problem isn't really with quantum encryption, it's with the technical implementation. And anyway, according to the article, they've already figured out a way to detect the hack and defeat it, so it's still pretty solid.

Makorov informed both companies of the details of the hack before publishing, so that patches could made, avoiding any possible security risk.

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.

Quantum is for Quacks

[Anonymous Coward]

This is what you get when even educated men can't make sense of your technology.

Pretty obvious now we need to return to traditional cryptosystems such as rot13 etc.
Arguably not the most secure, but it is efficient. And for military use, where security
requirements are higher, triple-rot13 is an option.

Re:Commercial Systems

[PseudonymousBraveguy]

Quantum cryptography is academic at this point. It is not as strong as old fashioned cryptography (like AES) and is much more expensive. Then I realized that there is no reason that someone can't use both.

Quantum crypto (at this point) is a key exchange mechanism. Thus, it doesn't compare to AES at all. You HAVE to use quantum crypto together with a classical exncryption algorithm. However, if you use quantom crypto you care about 100% theoretical security. Else you would simply use DH or any other well-known classical key exchange. And if you care about 100% theoretical security, there is no alternative to OTP.

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.

alice and bob

[brainscauseminds]

Poor Alice and Bob, they do not have a chance ever to live normal lives without hordes of geeky cryptographers debating/fighting over every bloody bit they exchange.

Re:Commercial Systems

[julesh]

Except that to be able to use quantum crypto at all, you need to provide a physical way to pass the quantum state. And with that requirement, why won't you just pass the key the good old fashioned way? Strictly more secure, and much cheaper.

More secure? Hardly. All you have to do is eavesdrop on the key exchange and you have the key. In a real world scenario, typically this means bribing a few security guards, breaking into one of the communicators' homes or offices and retrieving the key from their computer, or intercepting a message sent over a physical line, probably encrypted via a non-100%-reliable cryptographic system, with the (at least) theoretical possibility that the encryption on the key exchange can be broken.

In a properly implemented quantum crypto system, this is theoretically impossible: the key passes directly from one endpoint to the other, and any interference between the two is easily detectable. It isn't stored for longer than the message takes to be sent, so breaking in to retrieve it is impractical. Done properly, the quantum crypto system is as secure as it is possible to be. As it happens, the system here was not done properly; it failed to detect interference on the line (and as ability to detect interference is, essentially, the point of quantum crypto, this is bad news).

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:Why 'hackers' and not 'researchers'?

[Vadim Makarov]

with the manufacturer's full approval to boot

I'm not sure the manufacturers would approve the existence of our lab if they could dictate it. Thankfully we are independent and need not seek their approval. The manufacturers did appreciate responsible disclosure, though. I don't know how this hacking affects their business in the short term (may as well be detrimental to sales), even though it is surely good for business in the long term as it leads to more secure systems.

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.

Re:It seems that you could detect this

[PseudonymousBraveguy]

No it doesn't – it just makes the software more expensive to write. It's entirely possible to write software that has key properties proved to be correct and bug free,

It's not only the software. There's a lot of hardware involved, most of which could have bugs of some kind (e.g. for this hack you'd have to prove that your sensor can reliably detect that it's still in "quantum mode"). And after you have proven a lot of properties off all your hard- and software, you'll have to prove that all those properties are actually sufficient for achieving perfect security.

Article Makes No Sense

[SeekerDarksteel]

The article is either missing massive details or these researchers are vastly overstating the power of their technique. The entire _point_ of quantum key exchange is that if Eve intercepts the signal she cannot tell if she read a 0 or a 1 because she does not know which basis the 0 or 1 was generated in. Even IF Eve passed a 1 along every time she read a 1, when Alice and Bob go to do the basis comparison over the standard channel they will notice errors because Eve read the signal in the wrong basis and passed along an incorrect value.

I've tried reading the actual journal paper, but unfortunately they just seem to handwave this problem away. Maybe there's a reason they can, but its sure as hell not explained as far as I can see unless they're assuming Eve has also compromised the classical channel as well as the quantum channel.

Re:pwned

[WED Fan]

Why the GP was modded troll is beyond me. This is a "huge kick in the balls". Isn't the point of QC to make it easy to detect if someone has even listened in, let alone broken anything? I'd have to say that what it means is the current implementation of QC is an epic fail. Back to the old drawing board.