186 reputation
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bio website lac.u-psud.fr/…
location Paris, France
age 38
visits member for 3 years, 4 months
seen Nov 14 at 13:49

Researcher in quantum information, mainly on cryptography.


Sep
15
comment Why are we advising PKI if we know that quantum computers will break them?
People working in quantum computation (aka my colleagues) estimate the arrival date of quantum computers between 20 and 200 years from now. In other words they agree on one thing: it is beyond the predictable technological horizon ! I really do not think anyone serious think we will have a quantum computer able to break classical cryptography in the next decade.
Sep
11
comment Quantum key exchange skepticism/confusion
You can do this, but it amounts to assume technological limitation to Eve, which 1) is always difficult to define rigorously 2) doesn’t really improve the protocol performance by a lot. So yes, it is possible, but it is not usually not worth it.
Sep
11
comment Quantum key exchange skepticism/confusion
@RickyDemer: I don’t really understand your question,but I’ll explain the things in another way, hoping to answer the question by chance ! There exist a (unknown) maximal value $e^*$ for the tolerable error rate. Alice and Bob can exchange a key if and only if their error rate $e$ obeys $e<e^*$. An upper bound $u≥e^*$ is often given by an explicit attack (like $u=25\%$ above), but we want a lower bound $l≤e^*$ ($l=11\%$ above), such that $e<l$ ensures $e<e^*$. Finding $l$ is not trivial, since one has to take account of an adversary smarter than us, to stay on the safe side!
Sep
10
comment Quantum key exchange skepticism/confusion
On your other comment, I don’t know how you derive the 68% figure, which is probably wrong, but the idea is correct.
Sep
10
comment Quantum key exchange skepticism/confusion
On Eve’s Balance : exactly ! This QKD transforms spyinf into a denial of service attack. In practice, the errors will come from technical imperfection, but Alice and Bob cannot be sure. This is what limits in practice the range of QKD
Sep
10
comment Quantum key exchange skepticism/confusion
Nice to read a simultaneous, but really similar answer to mine !
Sep
10
comment Quantum key exchange skepticism/confusion
More inforamtion theoretic details about modern security proofs for QKD are available p95 of this ETHZ course, but you’ll need to familiarize yourself with Smothh Quantum Rényi entropies (introduced earlier in the same course) in order to extract something from this link...
Dec
16
comment What kind of Quantum cryptography technology(protocols) can be used for Mobile Ad hoc networks(MANETS)?
Nice answer. I just have a minor point : daylight QKD open air has been done since at least 2000 arxiv.org/abs/quant-ph/0001088 , so it's not only at night and far away from civilisation.
Mar
30
comment Feedback on rolling my own entropy gatherer
The random.c file of the linux kernel is fully commented and explains its mode of operation really clearly, even for people (like me) who don't read C