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Hot answers tagged quantum-cryptography

7

I see two problems with this idea. The first problem is Shor's algorithm; that's a quantum algorithm that is able to find the cycle length of a group (and if you can solve that problem, it is easy to factor and compute discrete logs). In this case, if we define the group of elements defined by the initial start state in the signature, where $H^n$ is the ...

6

Actually, most of the primitives that are currently believed to be secure FHE methods would appear to be quantum resistant; a partial list would include Craig Gentry's original scheme based on ideal lattices, BGV (based on ring-LWE), and this NTRU-based approach. All three are based on hard problems that are not susceptible to Shor's algorithm.

6

The statement a 15360-bit RSA key is the equivalent to a 256-bit symmetric key does not take into account quantum algorithms. In fact, it is based on a specific computation model. It is just based on the fact that there exist sub-exponential algorithms for factoring and therefore you need longer keys than when using symmetric-key crypto where it is ...

3

ECC is not resistant against quantum computers. Quantum complexity for breaking RSA and ECC are $O(\frac{s^9}{{(\log (s))}^5})$ and $O(s^3)$ respectively. Which $s$ is security level $(80-96)$. So as SEJPM mentioned in comments, "ECC is less resistant against quantum computers than RSA". One of newest post quantum cryptographic schemes is isogeny ...

2

If we assume that Alice is the one sending the photons, and Bob is the one receiving them, then Bob selects random bases to take the measurements, and then announces them (both to Alice and any potential attacker) after he has taken those measurements. An attacker cannot use that announcement to decide how to take measurements himself, as he doesn't hear it ...

1

While Poncho's answer already handles some issues with periodicity, there might be some other, functional issues: You have to make sure that the PRNG can be publicly evaluated on an intermediate value of the chain (to allow verification). If you consider PRNG's like block ciphers in counter mode (or similar constructions) you have the fast accessibility ...

1

Bob and Alice then take the correct configurations, and they convert those to a prearranged code, which could be, as an example, that a correctly guessed diagonal detector is 0, and a correctly guessed rectilinear detector is 1. This way an encryption key will be composed. I believe that's where you got it a bit off. A correctly guessed ...

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