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Quantum entanglement is such a neat phenomenon, but secure communication feels like such a boring application. How much extra security would a quantumly protect
by TipVFL 9y ago
Quantum entanglement is such a neat phenomenon, but secure communication feels like such a boring application. How much extra security would a quantumly protected communication channel provide over just using some really heavy encryption sent in a normal manner?
- alex_anglin 9y agoThat observation of the communication would break the link, versus capture and (attempt to) decrypt?
- Klathmon 9y agoThat to me seems like the coolest possibility. Encryption that breaks if someone other than the authorized parties observes it. Something which isn't possible with "traditional" encryption.
- nsxwolf 9y agoSounds like a denial of service attack though. Just keep trying to read messages and render the channel unusable.
- teraflop 9y agoThis kind of observation would already require physical access to the communications medium (e.g. a fiber optic cable). So if you could DoS a quantum encrypted channel by measuring it, you could equally well DoS a classical channel by just cutting the fiber.
- QAPereo 9y agoIf you have secrets to keep, and your adversaries have that kind of access, better a DDOS than a leak. Edit: This kind of observation would already require physical access to the communications medium (e.g. a fiber optic cable). So if you could DoS a quantum encrypted channel by measuring it, you could equally well DoS a classical channel by just cutting the fiber. The comment just above mine, which does a better job than me of explaining the degree of access required. Besides which, it’s not as though you can only use this. You try your quantum channel first, and if it’s down you know you’re under attack, and act accordingly with your Classical backups.
- thaumasiotes 9y agoWell, the whole point of encryption is that you can send your message through despite the fact that your adversary can see it. Replacing that with a system where your adversary can't see your message, and neither can your correspondent, is a downgrade, not an upgrade.
- mathw 9y agoThat depends entirely on your application.
- thaumasiotes 9y agoCould you give some examples of applications of encryption where the purpose is not to send a message that adversaries may see but cannot understand?
- eru 9y agoEncrypting data at rest, for example. (Depends on how wide your definition of 'send' is.)
- dsacco 9y ago> Encryption that breaks if someone other than the authorized parties observes it. Something which isn't possible with "traditional" encryption. As stated, this isn't possible with encryption enabled by quantum key exchange, either, nor is it an intended goal of the procedure. Quantum key exchange empowers integrity in the cryptographic key exchange process, but it doesn't intrinsically do anything to empower confidentiality (encryption) or authentication. If you successfully share a key with another party using a channel established via quantum entanglement, you will be (theoretically) capable of discerning with certainty whether or not there has been an attempt to record the key "outside" the channel. The quantum innovation ceases once the key has been successfully shared. The ciphertexts encrypted with a key shared via quantum key exchange are just like ciphertexts encrypted with a key shared via traditional key exchange. They will not "break" if observed by an unauthorized party; in fact, there is no way to endow a ciphertext with that property. Either a party has the correct key or the don't, but the ciphertext will not "self-destruct" or cease to become usable if the incorrect key is used. I feel this is an important nit to pick because even if you understand this, others reading your comment might not. Conceptually speaking, assurance of secure channel integrity is very different from assurance of confidentiality. It would be more accurate to say that in a quantum channel, you could exchange information in such a way that it cannot feasibly be read or tampered with; however, if the ciphertext were extracted from that channel, it would not be meaningfully different from a ciphertext extracted from TLS.
- Klathmon 9y agoNo but if you treat the "key exchange" process as a one time pad key and simply xor it with the message it doesn't matter that the actual ciphertext can be intercepted, since it's impossible to decrypt it. The only catch is that you would need to delay reading the "key" until the last possible second, and of course side channel attacks are still possible on both sides. Now with how complicated and costly creation of the entangled particles will be, I'm assuming that usage like this will be very very rare, but it's still possible.
- dsacco 9y ago> No but if you treat the "key exchange" process as a one time pad key, it doesn't matter that the actual ciphertext can be intercepted, since it's impossible to decrypt it. Sure, I'm not saying you can't achieve information theoretic security. My point here is that discussion of quantum key exchange should use precision in terminology - integrity and confidentiality are meaningfully different. If the ciphertext from a quantum channel is extracted (in whatever way), it is not more secure than a ciphertext in which the keys were shared in person and promptly destroyed via Cold War-era means. You won't be aware of an adversary trying to break the encryption once they have it in their possession, and the ciphertext won't "break" if plied with an incorrect key (though it would be secure for other reasons). Rather, you'd know if the key exchange process is being broken, or if information was not transmitted correctly.
- urgoroger 9y agoYes, this is pretty much the basis to quantum key distribution protocols, and probably one of the first studied uses of quantum information in general. Consider BB84 (http://www.cse.wustl.edu/~jain/cse571-07/ftp/quantum/ http://www.cse.wustl.edu/~jain/cse571-07/ftp/quantum/, https://en.wikipedia.org/wiki/BB84 https://en.wikipedia.org/wiki/BB84, apparently the first quantum cryptography protocol), which would allow the transmission of a one time pad with an any eavesdropper being unnoticed with provably exponentially decreasing probability in terms of key length. The one time pad can then be used to securely transmit data. Thus it is possible to transmit arbitrary (classical) data with exponentially decreasing probability that we do not detect an eavesdropper. Alice and Bob can communicate with each other knowing that there is provably pretty much no chance that anyone else knows what they said to each other.
- reacweb 9y agoencryption breaks if someone "observes more" than is allowed by error correction. Physical world is rarely binary.
- jacoblambda 9y agoWell it basically boils down to if somebody observes enough to be able to make any use of it.
- TipVFL 9y agoThat seems very exploitable, an enemy could theoretically intercept all your communications, just to prevent you from communicating.
- Asooka 9y agoA channel that disappears the moment you look at it seems like it would be very vulnerable to DoS.
- amelius 9y agoWhat is the practical application of this then, considering that you can choose an arbitrarily large key to make eavesdropping or tampering practically impossible? I don't get what's so exciting about this. Or does this only become practically useful once quantum computing breaks traditional encryption?
- yoz-y 9y agoFrom what I have gathered it is relatively easy to create protocols that are not insecure in presence of quantum computing.
- tonmoy 9y agoYou would know that a third party is not even storing your encrypted data for a future time when that encryption method/implementation may become obsolete.
- nixpulvis 9y agoSeems to me you avoid the problem of large bad actors collecting a lot of encrypted data with the goals of decyrypting one day with better hardware. That said, who knows what kinda fun could be had with the side channels of our own physics system.
- cookingrobot 9y agoOne-time pads seem like a much easier solution, and they're never breakable given any amount of computation. They require upfront preparation to trade the pad, but seem a lot easier than quantum anything.
- dsacco 9y agoI'm in the camp that quantum cryptography (i.e. quantum key exchange) is silly. If quantum key exchange is not easier to use than a one-time pad, that's an argument against both, not an argument for a one-time pad. One-time pads are approximately never worth their effort, and in the modal case would just encourage poorer security overall.
- jandrese 9y agoThe problem with one time pads is that you have to deliver the pad to your recipient first without it being observed in transit. This typically requires cumbersome physical security, and even then you can't be 100% sure. Transmitting the one time pad over a medium that you can be positively sure nobody has eavesdropped on could make it practical. If someone does eavesdrop on the signal than you ignore that one time pad. This is the technology that makes one time pads finally practical, at least in some cases.
- jacoblambda 9y agoI'd make the argument that one time pads are way more practical with access to quantum key exchanges.
- zitterbewegung 9y agoCurrent production quantum key distribution systems are actually succeptable to attack by gaming the systems that detect the particles and going beyond their limitations .
- binarytransform 9y agoSource?
- filleokus 9y agoI'm not sure if GP is talking about this https://en.wikipedia.org/wiki/Quantum_key_distribution#Trojan-horse_attacks https://en.wikipedia.org/wiki/Quantum_key_distribution#Troja... or not, but that's definitely an issue.
- deleted 9y ago[deleted]