3 ms·

Following nabla9's suggestion in the parallel reply: http://www.nist.gov/manuscript-publication-search.cfm?pub_id=901595 http://www.nist.gov/manuscript-publica

by acqq 10y ago

Following nabla9's suggestion in the parallel reply: http://www.nist.gov/manuscript-publication-search.cfm?pub_id=901595 http://www.nist.gov/manuscript-publication-search.cfm?pub_id... "Bennet, Bernstein, Brassard, and Vazirani demonstrated that quantum computers cannot provide an exponential speedup for search algorithms, suggesting that symmetric encryption algorithms, one-way functions, and cryptographic hash algorithms should be resistant to attacks based on quantum computing [4]." (4: C. Bennett, E. Bernstein, G. Brassard, and U. Vazirani. Strengths and weaknesses of quantum computation. Special Issue on Quantum Computation of the Siam Journal of Computing, Oct. 1997.) Note, this was already known in 1997, two decades ago. After all the discussion up to now, I believe even more in djb's conclusion: "Ultimately the victims are the users. A quarter of a billion Euros, despite being explicitly aimed at communication security, will actually be devoted to quantum technologies that are much less secure than modern real-world cryptography. The occasional users who can afford to deploy quantum cryptography won't realize how easy it is to break. Meanwhile a similar level of funding will be sensibly devoted to quantum computing, but without a proper acknowledgment of the resulting security apocalypse, and without a corresponding level of funding for the most plausible plan to prevent this apocalypse." However it's sure that not only EU scientists make grandiose claims: http://www.macleans.ca/society/science/trudeau-versus-the-experts-quantum-computing-in-35-seconds/ http://www.macleans.ca/society/science/trudeau-versus-the-ex... "With a quantum computer, we hope to find a more efficient way to produce artificial fertilizer, having direct impact on food production around the world, and we hope to combat global warming." Ugh. And cure cancer and make your pennies bigger. Hey it's quantum. Anyway Chinese already sell the "quantum diagnostics devices" comparably "amazing": https://www.youtube.com/watch?v=iaDQgVwKO-Y https://www.youtube.com/watch?v=iaDQgVwKO-Y

ThePhysicist 10y ago
That quantum computers can't break symmetric cyphers efficiently is well-known, I just don't see why this makes quantum cryptography obsolete, as it is mostly about secure key exchange. Also, why are quantum algorithms less secure? There are some possible exploits (e.g. due to problems in the detector), but theoretically the encryption is unbreakable with our current understanding of Physics.
- acqq 10y ago
  > why are quantum algorithms less secure? It's not about the "algorithms" it's about everything around them. The security is a strong as the weakest link: Again djb, the original article we are supposed to comment here: "Fundamentally, quantum cryptography makes the same mistake as locked-briefcase cryptography: it aims for security in an oversimplified model of the physical world, takes resources away from more serious security techniques, and ends up damaging security in the real world. Quantum cryptography, like locked-briefcase cryptography, also relies on a preexisting secure channel (to authenticate choices of "bases" by Alice and Bob), and does nothing to address the problems handled by public-key cryptography." See also my comment to "quantum credit cards" here as another illustration.
  - ThePhysicist 10y ago
    But why does this make research on quantum cryptography worthless? Building a system that delivers the full promise of quantum encryption and addresses the weaknesses of the system is the very goal of such research. Classical encryption schemes would never have gotten to the point they are today without this kind of research funding, so why don't we grant this to quantum cryptography as well? And if the method is so fundamentally flawed as some people want to make us believe, why are several dozen research organizations around the world pursuing it? And why is it a bad thing to talk about applications that seem far-fetched today, like "quantum credit cards"? Blockchain-based currencies were probably also a pretty far-fetched concept 20 years ago, but today they have a fixed place in the currency eco-system.

by acqq 10y ago

ThePhysicist 10y ago

That quantum computers can't break symmetric cyphers efficiently is well-known, I just don't see why this makes quantum cryptography obsolete, as it is mostly about secure key exchange. Also, why are quantum algorithms less secure? There are some possible exploits (e.g. due to problems in the detector), but theoretically the encryption is unbreakable with our current understanding of Physics.

acqq 10y ago
> why are quantum algorithms less secure? It's not about the "algorithms" it's about everything around them. The security is a strong as the weakest link: Again djb, the original article we are supposed to comment here: "Fundamentally, quantum cryptography makes the same mistake as locked-briefcase cryptography: it aims for security in an oversimplified model of the physical world, takes resources away from more serious security techniques, and ends up damaging security in the real world. Quantum cryptography, like locked-briefcase cryptography, also relies on a preexisting secure channel (to authenticate choices of "bases" by Alice and Bob), and does nothing to address the problems handled by public-key cryptography." See also my comment to "quantum credit cards" here as another illustration.
- ThePhysicist 10y ago
  But why does this make research on quantum cryptography worthless? Building a system that delivers the full promise of quantum encryption and addresses the weaknesses of the system is the very goal of such research. Classical encryption schemes would never have gotten to the point they are today without this kind of research funding, so why don't we grant this to quantum cryptography as well? And if the method is so fundamentally flawed as some people want to make us believe, why are several dozen research organizations around the world pursuing it? And why is it a bad thing to talk about applications that seem far-fetched today, like "quantum credit cards"? Blockchain-based currencies were probably also a pretty far-fetched concept 20 years ago, but today they have a fixed place in the currency eco-system.