5 ms·

Im not an expert in this field but a colleague of mine did mention the mitm can be remedied using newer device independent qkd techniques. The main issue as I u

Im not an expert in this field but a colleague of mine did mention the mitm can be remedied using newer device independent qkd techniques. The main issue as I understand is QKD systems have very poor key rates, hence they arent very efficient.

yodon 5y ago
Apologies in advance as it's been a very long time since I was focused on Quantum Cryptography, so please be kind if I'm garbling things or stating things poorly. I haven't thought about this stuff in 20+ years so the mental paths are a bit rusty. The ultimate purpose of quantum crypto is to prevent eavesdropping on your channel. With quantum crypto, mitm attacks will almost always be the easiest form of attack so you can't trust quantum crypto if you can't prevent mitm attacks. If you share enough information to detect and prevent an mitm attack, you share enough info to form a classical crypto system with equivalent protection (as in, if you don't know who you are talking to, there's fundamentally no way to know if you've been mitm'ed, quantum crypto or not, so you have to share some kind of info with the other party in order to prove the end of the system is your intended recipient, and you can't bootstrap that sharing with your quantum crypto system so you must have found some secure key distribution mechanism to do so prior to using the quantum system - this is fundamentally the key distribution problem, and quantum doesn't actually help with this part it just obfuscates that it's happening because people get distracted by the shiny uncertainty principle math). That required shared info is what the security of your quantum crypto "protected" system is actually built on. You can do just as well at protecting your transmissions against eavesdropping using classical methods far more cheaply and far more easily. Someone, (possibly Bernstein?, it's been a long time since I was thinking about this stuff), wrote a paper in the late 90's on communicating over noisy channels (or using noisy channels to a public random number source? as I said, it's been 20 years) and showed as long as you could estimate/demonstrate that your channel had lower noise than your opponents you could use the knowledge of that noise difference to deliver any desired level of security through the channel. That paper didn't make an explicit connection to quantum crypto because quantum crypto was so new and so niche at the time, but all Quantum Crypto is really doing is providing a way to get a good estimate of the noise ratios between your channel and your attacker's channel. That's handy, but mostly theater. The rest works just as well classically.

yodon 5y ago

Apologies in advance as it's been a very long time since I was focused on Quantum Cryptography, so please be kind if I'm garbling things or stating things poorly. I haven't thought about this stuff in 20+ years so the mental paths are a bit rusty. The ultimate purpose of quantum crypto is to prevent eavesdropping on your channel. With quantum crypto, mitm attacks will almost always be the easiest form of attack so you can't trust quantum crypto if you can't prevent mitm attacks. If you share enough information to detect and prevent an mitm attack, you share enough info to form a classical crypto system with equivalent protection (as in, if you don't know who you are talking to, there's fundamentally no way to know if you've been mitm'ed, quantum crypto or not, so you have to share some kind of info with the other party in order to prove the end of the system is your intended recipient, and you can't bootstrap that sharing with your quantum crypto system so you must have found some secure key distribution mechanism to do so prior to using the quantum system - this is fundamentally the key distribution problem, and quantum doesn't actually help with this part it just obfuscates that it's happening because people get distracted by the shiny uncertainty principle math). That required shared info is what the security of your quantum crypto "protected" system is actually built on. You can do just as well at protecting your transmissions against eavesdropping using classical methods far more cheaply and far more easily. Someone, (possibly Bernstein?, it's been a long time since I was thinking about this stuff), wrote a paper in the late 90's on communicating over noisy channels (or using noisy channels to a public random number source? as I said, it's been 20 years) and showed as long as you could estimate/demonstrate that your channel had lower noise than your opponents you could use the knowledge of that noise difference to deliver any desired level of security through the channel. That paper didn't make an explicit connection to quantum crypto because quantum crypto was so new and so niche at the time, but all Quantum Crypto is really doing is providing a way to get a good estimate of the noise ratios between your channel and your attacker's channel. That's handy, but mostly theater. The rest works just as well classically.