A way to intercept photons of light to create a security leak has been discovered.PunchstockQuantum 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.
Quantum cryptography is often touted as being perfectly secure. It is based on the principle that you cannot make measurements of a quantum system without disturbing it. So, in theory, it is impossible for an eavesdropper to intercept a quantum encryption key without disrupting it in a noticeable way, triggering alarm bells.
Vadim Makarov at the Norwegian University of Science and Technology in Trondheim and his colleagues have now cracked it. "Our hack gave 100% knowledge of the key, with zero disturbance to the system," he says.
In standard quantum cryptographic techniques, the sender — called 'Alice' for convenience — generates a secret key by encoding classical bit values of 0 and 1 using two different quantum states of photons, or particles of light. The receiver, 'Bob', reads off these bit values using a detector that measures the quantum state of incoming photons. In theory, an eavesdropper, 'Eve', will disturb the properties of these photons before they reach Bob, so that if Alice and Bob compare parts of their key, they will notice a mismatch.
In Makarov and colleagues' hack, Eve gets round this constraint by 'blinding' Bob's detector — shining a continuous, 1-milliwatt laser at it. While Bob's detector is thus disabled, Eve can then intercept Alice's signal. The research is published online in Nature Photonics today1.
Breaking the rules
The cunning part is that while blinded, Bob's detector cannot function as a 'quantum detector' that distinguishes between different quantum states of incoming light. However, it does still work as a 'classical detector' — recording a bit value of 1 if it is hit by an additional bright light pulse, regardless of the quantum properties of that pulse.
That means that every time Eve intercepts a bit value of 1 from Alice, she can send a bright pulse to Bob, so that he also receives the correct signal, and is entirely unaware that his detector has been sabotaged. There is no mismatch between Eve and Bob's readings because Eve sends Bob a classical signal, not a quantum one. As quantum cryptographic rules no longer apply, no alarm bells are triggered, says Makarov.
"We have exploited a purely technological loophole that turns a quantum cryptographic system into a classical system, without anyone noticing," says Makarov.
Makarov and his team have demonstrated that the hack works on two commercially available systems: one sold by ID Quantique (IDQ), based in Geneva, Switzerland, and one by MagiQ Technologies, based in Boston, Massachusetts. "Once I had the systems in the lab, it took only about two months to develop a working hack," says Makarov.
This is the latest in a line of quantum hacks. Earlier this year, a group led by Hoi-Kwong Lo at the University of Toronto in Ontario, Canada, also showed that an IDQ commercial system could be fully hacked. However, in that case, the eavesdropper did introduce some noticeable errors in the quantum key2.
Grégoire Ribordy, chief executive of IDQ, says that the hack of Makarov and his group is "far more practical to implement and goes further than anything that has gone before".
Both IDQ and MagiQ welcome the hack for exposing potential vulnerabilities in their systems. Makorov informed both companies of the details of the hack before publishing, so that patches could made, avoiding any possible security risk.
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"We provide open systems for researchers to play with and we are glad they are doing it," says Anton Zavriyev, director of research and development at MagiQ.
Ribordy and Zavriyev stress that the open versions of their systems that are sold to university researchers are not the same as those sold for security purposes, which contain extra layers of protection. For instance, the fully commercial versions of IDQ's system also use classical cryptographic techniques as a safety net, says Ribordy.
Makarov agrees that the hack should not make people lose confidence in quantum cryptography. "Our work will ultimately make these systems stronger," he says. "If you want state-of-the-art security, quantum cryptography is still the best place to go."
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References
- Lydersen, L. et al. Nature Photonics advance online publication doi:10.1038/NPHOTON.2010.214 (2010).
- Xu, F., Qi, B. & Lo, H.-K. Preprint at http://arxiv.org/abs/1005.2376v1 (2010).
Just want to add a link to page with pictures on how we did the hack.
Are these cryptographic systems truly quantum? If systems are still coupled to a 'classical detector' then isn't the encryption binary and not quantum?
If Eve intercepts Alice's photons and in some way has to decide when to block Bob's receptor by sending a pulse or not, this decision-making takes time. While not familiar with the circuit or if the time required to intercept, decide, and emit the false beam is measurable or not. Common sense tells me that there has to be at least some delay.
Therefore sending these data "pulses" at regular intervals, checking the timing of the arriving signal to see that it matches the expected pattern, and looking for a delay would indicate that someone is eavesdropping on the system, no?
Jarod: they are truly quantum, before we fire up our blinding laser (then they become classical).
Steven: yes, if you just cut the fiber line and insert some electronic equipment, there will be a bit of extra delay to the signals. However, this is a fiber line where signals travel at 2/3 the speed of light (which can be substituted by direct line-of-sight radio communication at the speed of light), and also the fiber line is never quite straight (some corners can be cut). It is trivial for Eve to shorten signal travel time in a part of the line and fully compensate the delay her equipment introduces, making the overall extra delay zero.
Regarding the claim that "If you want state-of-the-art security, quantum cryptography is still the best place to go." --
Most applied cryptographers would probably disagree with you there. I know the physics seems fancy and cool, but from a cryptography and information security perspective, quantum cryptography solves the wrong problem.
I would refer you to Perry Metzger's cryptography mailing list for extensive discussion of this point. e.g.,
http://www.mail-archive.com/cryptography@metzdowd.com/msg07680.html
http://www.mail-archive.com/cryptography@metzdowd.com/msg00818.html
http://www.mail-archive.com/cryptography@metzdowd.com/msg00847.html
and the ensuring discussion threads.
See also the comments to this article; the article is lame, but the comments are outstanding:
http://hackreport.net/2006/12/13/quantum-cryptography-its-some-kind-of-magiq/
I'd like to make sure people don't forget some prior art: particularly, Adi Shamir's side-channel attack on quantum cryptography, which he described at Cryptec 1999. It's a bit different, but it has some similar elements. See my comments at the end of the following article ( http://www.newscientist.com/article/dn14866-laser-cracks-unbreakable-quantum-communications.html ) for a few more details.
Can you point to a published record of Adi Shamir's attack?
I think you may be referring to the Trojan horse attack on quantum crypto, which is covered in a couple papers (both published after 1999, none of them Shamir's; but the idea appeared around this time).
I admit there is an interception of the message intended to be exchanged between "Alice" and "Bob". How does "Eve" access the decryption codes in the QKD? In other words if you do manage to install an "Eve" between satellite and the ground receiver, what sort of effect should we expect and on what scale?
a very nice thread and discussion indeed. Thank you nature.com. I found what i was searching for.
Great job Makarov..way to go..!!!
Vadim can you explain what you mean... before we fire up our blinding laser, then they become classical? how did it change or did it? Still not sure it started as a quantum system.
William, you should look at Figure 1 and its explanation in the article. The APDs are in quantum single-photon detection regime when biased above the breakdown voltage, but they are just classical photodiodes when biased below the breakdown voltage. When we shine a bright laser, the voltage at the detector permanently falls below breakdown (because the illuminated APD conducts photocurrent and its biasing circuit has a non-zero impedance, Ohm's law: I times R equals a voltage drop). An APD biased below breakdown is a classical photodetector with a classical sensitivity threshold.
This is an important and impressive work, although it is not the first successful quantum hacking on a commercial quantum crypto-system. The first quantum hacking experiment against a commercial quantum crypto-system was actually published in 2008 (Y. Zhao et al., "Quantum hacking: Experimental demonstration of time-shift attack against practical quantum-key-distribution systems", Physical Review A, 78: 042333, 2008).
Moreover, I would like to point out that, in order to be really sure that the counter-measures work and do not introduce new loopholes, it is important for the QKD manufactures to publish details of their counter-measures. After all, QKD security should be based on quantum physics, rather than "security from obscurity".
Originally, the security of a cryptogram depended on the secrecy of the entire encrypting and decrypting procedures. Today, however, we use ciphers in which the algorithm for encrypting and decrypting could be revealed to anybody without compromising the security of a particular message. In such ciphers a set of specific parameters, called a key, is used together with the plaintext as an input to the encrypting algorithm, and together with the cryptotext as an input to the decrypting algorithm. The encrypting and decrypting algorithms are publicly announced; the security of the cryptogram depends entirely on the secrecy of the key. To prevent this being discovered by accident or systematic search, the key is chosen as a very large number. Once the key is established, subsequent secure communication can take place by sending cryptotext, even over a public channel that is vulnerable to total passive eavesdropping, such as public announcements in mass media. However, to establish the key, two users, who may not be in contact or share any secret information initially, will have to discuss it, using some other reliable and secure channel. But since interception is a set of measurements performed by an eavesdropper on a channel, however difficult this might be from a technological point of view, any classical key distribution can in principle be passively monitored, without the legitimate users realizing that any eavesdropping has taken place.
Yeah, I'm with Sammy at this moment... Good additional info Sam..!!
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The next time I read a weblog, I hope that it doesnt disappoint me as a lot as this one. I mean, I know it was my option to learn, but I truly thought youd have something fascinating to say. All I hear is a bunch of whining about something that you could repair when you werent too busy looking for attention.
It seems like a very interesting idea. However, might I add that an easy way around this supposed easy hack is to vary the light pulse frequency using a random generation key. These types of techniques were known in real usage in the field as well as in sic fi fantasy shows. "ROTATE the SHIELD FREQUENCY Mr. DATA" ENGAGE.
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It is trivial for Eve to shorten signal travel time in a part of the line and fully compensate the delay her equipment introduces, making the overall extra delay zero.Essay Writing
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Ha, Quantum Cryptography what a term haha, makes it sound like a whole new science, I've got a mate working as a quantum cryptographer and it's all he thinks and talks about all day tricyclic antidepressants clonazepam side effects types of kisses xanax side effects
The cryptogropher who brought it up said it was not a flaw with quantum crypto itself (quantum crypto is unbreakable because of the laws of physics), but rather that the implementation was flawed. Implementation is everything with crypto systems, whether they be QC or classical. I suspect this attack is also a result of a flaw in the implementation. template website
Yes after that events ,everyone wants to be in the picture with Eve. The members of Quantum Hacking group (quantum hackers) are from University of Science and Technology, Norway (UCTN) and Center for Quantum Technologies, National University of Singapore. Eve, is a jumble of wires and electronic components used to lazer Quantum Key Distribution. Its name derives from the English "eavesdropping" which means "spy" or "espionage". The researchers used Eve to decrypt a type of an encrypted communication, thought to be inviolable, called quantum encryption.
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I dont have any idea about hacking but with the issue that hacking that doesnt leave a trace could be a good thing and a bad thing. Its good if its done to solve and help others and create new technology but bad if its done in the opposite way. Keira Jones of Sulfate Free Shampoo and Shellac
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I never thought this would actually work with hte lasers. Some people here in Finland have tried something similar but failed.
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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.
Quantum cryptography is often touted as being perfectly secure. It is based on the principle that you cannot make measurements of a quantum system without disturbing it. So, in theory, it is impossible for an eavesdropper to intercept a quantum encryption key without disrupting it in a noticeable way, triggering alarm bells.
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In standard quantum cryptographic techniques, the sender — Testosteron 'Alice' for convenience — generates a secret key by encoding classical bit values of 0 and 1 using two different quantum states of photons, or particles of light.
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Betting that every method of security, given time, money, and knowledge, has a way of being bypassed, is safe, lol. Outside of that, no, nothing is, lol.
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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.
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There is no mismatch between Eve and Bob's readings because Eve sends Bob a classical signal, not a quantum one. As quantum cryptographic rules no longer apply, no alarm bells are triggered. Timbukto of paracord bracelet
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It's pretty amazing how hackers can get around these systems. IMO they should have the open versions of their systems that are sold to university researchers be the same as those sold for security purposes. Why? To see if the extra layers of protection can be cracked and improve any weaknesses in the system.
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It's pretty amazing how hackers can get around these systems. IMO they should have the open versions of their systems that are sold to university researchers be the same as those sold for security purposes. Why? To see if the extra layers of protection can be cracked and improve any weaknesses in the system.
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Quantum cryptography is a completely new field of encryption. Some scientists also believe that in theory can provide a hundred percent safety data. At least my diary will be safe!
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If systems are still coupled to a 'classical detector' then isn't the encryption binary and not quantum? visit
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