# Tag Info

28

How does it compare to classical computers, performance-wise, for cryptanalytic tasks? Not at all - IBM's quantum computer cannot perform any nontrivial cryptanalytic task. For one, 53 physical qubits far too few to do anything interesting; for example, implementing SHA-256 would take thousands of logical qubits. For another, the qubits are not even close ...

17

can they (quantum computers) do such complicated computing (cryptanalysis)? Not currently. Current quantum computers (including the adiabatic variants specialized in quantum annealing) do not perform anything useful for cryptanalysis. In the future: we don't know. Is it possible quantum computers put the computer security in jeopardy? It is reasonable ...

12

Grover's algorithm on AES-128 If all of the problems of Grover's algorithm are solved then yes, otherwise no! Grover's algorithm provides quadratic speed up so AES-128 has 64-bit security in the terms of searching complexity of Grover's method. Grover's attack for AES-128 requires approximately $2^{64}$ successive AES evaluations. That is one has to set up ...

10

If quantum computers are physically feasible, then there are some algorithmic problems that they should be able to solve faster than classical computers. It happens that brute-force search and discrete logarithms are two of those problems. Unfortunately, the security of symmetric cryptosystems depends on brute-force search being hard, and the security of ...

6

Well, the best answer I can think of is by referring you to Scott Aaronson's wonderful blog. Quoting the very header of the blog: If you take just one piece of information from this blog: Quantum computers would not solve hard search problems instantaneously by simply trying all the possible solutions at once. So no, a quantum computer would not try ...

6

What is Quantum Cryptography? Today's "normal" cryptography relies mostly on mathematical principles. For example RSA is based on the practical difficulty of the factorization of the product of two large prime numbers, the so-called "factoring problem". Quantum cryptography (quote from Wikipedia): Quantum cryptography is the science of exploiting ...

5

It depends on the kind of quantum computer and how many logical qubits it has. Not all quantum computer designs are capable of breaking cryptographic systems. The popular adiabatic quantum computers, while very useful for certain tasks, have no cryptanalytic utility. Designs that are capable of running, say, Shor's algorithm are currently in their infancy. ...

5

But is there also a notion of computational security in quantum cryptography (assuming a polynomial-time quantum adversary)? No, not really, or at least, none that has been explored. The goal of Quantum Cryptography is to be secure, even if the adversary has a Quantum Computer and that they are computationally unbounded; that is, the goal is to rely (as ...

4

The Post Quantum Cryptography is a type of cryptography that lies on physics properties instead of mathematics , it has many algorithms and implementations like NTRU , McEliece , SIDH ... etc. But there is a difference between Post Quantum Cryptography and Quantum Cryptography Let's try to classify this: Quantum Privacy Amplification, which is the honest ...

3

Can I use Quantum encryption/decryption algorithms in IoT devices such as RaspberryPi, Arduino etc, or should the hardware infrastructure obey in quantum logic? The question needs to be reformulated as: Can I use Post-Quantum encryption/decryption algorithms in IoT devices (..) ? Yes. They can use such encryption/decryption/key exchange algorithms, ...

3

Considering quantum computing to break passwords in the online setup would be nonsense. In that setup, passwords are sent to a classical system testing the password. That seems to be the question's scenario. In the offline setup, the information that allows testing if a password is accepted or not is assumed to have leaked to the attacker (e.g. because the ...

2

I do not know if the result is true, since I did not check it, but note that this algorithm is not in the standard model of quantum computation. As the author himself put it: The Deutsch model of quantum computation is extended to allow for thermodynamically irreversible operations by allowing the system of interest to interact with an outside reservoir. ...

2

I've looked quite a bit into post-quantum cryptography, so I could tell you plenty of algorithms for that. Post-quantum cryptography is secure against a quantum computer, but can be executed on a classical system. Quantum cryptography on the other hand would need to be executed on a quantum computer, so even if you could find an implementation on GitHub or ...

2

MACs don't involve any key exchange. The ability to share the key is assumed, just like with symmetric encryption. I'd tend to recommend a 256 bit key over a 192 bit key, because the effective key length is halved. 96 bits effective security might be breakable eventually, 128 bits effective security basically never will without discovery of flaws in the ...

1

Privacy amplification (PA) cannot be done at all with only a QRNG (which I take to be a quantum random number generator). Privacy amplification resides further along the application stack, and requires two co-operating parties (Bob and Alice) and an opponent (Eve) listening in on their quantum channel within their quantum key distribution network (QKDN) :- ...

1

However, to my understanding, the only purpose of Shor's Algorithm is quickly finding the prime factors of very large numbers. Your understanding is incorrect. Shor's Algorithm is usable for both factoring integers and finding discrete logarithms. Shor's algorithm works in two parts. First, it turns the problem (factoring or discrete log) into one of ...

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