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Questions tagged [quantum-cryptanalysis]

Use this tag on questions about attacks that break cryptographic guarantees / security properties of primitives and protocols and utilize quantum computers as an essential part.

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5
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0answers
78 views

How would quantum computers affect password based encryption?

At first glance: Assuming that the output of the password hashing function is large enough, quantum computers should have no effect on password encryption as on symmetric cryptography in general. Is ...
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1answer
4k views

How does IBM's 53-bit quantum computer compare to classical ones for cryptanalytic tasks?

IBM just announced "a new 53-qubit quantum computer". How does it compare to classical computers, performance-wise, for cryptanalytic tasks? E.g. finding a 48- or 64-bit value whose SHA-256 has a ...
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1answer
161 views

Are there post-quantum cryptosystems with a gap between classical and quantum security?

Is there a gap between classical attacks and quantum attacks against some post-quantum security assumptions? (I'm particularly interested in asymmetric cryptography.) I understand that there is no ...
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2answers
237 views

How Will Quantum Computing Change Cryptography's Future? [closed]

Quantum computing is at the intersection of math, physics, and computer science. It seems so complicated that only large organizations could build such algorithms and have their own quantum computing ...
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0answers
43 views

Finding the period of a function with a single output qubit - impact on RSA

In this paper,May and Schlieper claim that one can find the period of a function $f()$ by embedding $h \circ f = h(f(x))$ for input $x$. This would have the immediate consequence of reducing the ...
11
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1answer
409 views

Is this paper's technique for factoring RSA 2048 with noisy qubits realistic?

A paper titled How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits has just come out which proposes a technique to factor RSA keys with moduli up to 2048 bits with a design ...
3
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1answer
104 views

Does the block size of a symmetric cipher impact the security of the cipher itself? [duplicate]

Will a 128 bit block have some security implication in post-quantum cryptography?
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3answers
368 views

Can Shor's algorithm factor multi-prime numbers?

I know that Shor's algorithm can factor semi-primes ($N = p \times q \space, \{p, \space q \in \Bbb{P} \space \vert \space p, \space q \gt 0 \} $). Assuming that all prime numbers are so large that ...
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Time-memory tradeoffs in Shor's algorithm

Can a quantum computer with insufficient qubits to factor an integer of a given size make any progress in factoring it? For example, what if a quantum computer is only one qubit short of what is ...
4
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2answers
66 views

Does a thermodynamic limit on key search apply to quantum computers?

There is (or at least was) a thermodynamic reasoning that any form of brute force key search would require an energy at least $k\,T$ per key tested, where $k$ is Boltzman's constant and $T$ the device'...
5
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1answer
160 views

Combining classical attacks and quantum cryptanalysis

I'm regularly reading that AES-256 is secure against quantum computers because Grover's algorithm will only halve the key strength (i.e. "only" require $\sqrt{2^l} = 2^{l/2}$ operations instead of the ...
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1answer
73 views

What happens when quantum-resistant cryptography is implemented using a quantum computer?

What happens when quantum-resistant cryptography is implemented using a quantum computer? Give the whole deal with the qubits, is this even a worthy action?
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2answers
3k views

Can quantum computers put computer security in jeopardy?

There are many articles about quantum computers describing how powerful they are in computing and that they can solve very complicated equations in a short time. One of the biggest security measures ...
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0answers
88 views

How many qbits are required to break Diffie-Hellman over a multiplicative group

There have been comparisons between RSA and ECDH with regards to the number of qbits (qubits) required to break the algorithm with a specific key size. But how many qbits are required to break "...
2
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1answer
140 views

Will using large keys with Classic cryptographic algorithms beat quantum computers?

This is a purely theoretical question. Everyone is talking about quantum cryptography being the next big thing as quantum computers will be much faster than the computers we have today. So, from my ...
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3answers
3k views

Largest integer factored by Shor's algorithm?

I'm studying Shor's quantum factoring algorithm. I was wondering what the largest integer is which they were able to factor with a small quantum computer. Does anybody has an idea about this?
4
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1answer
142 views

What are the implications of quantum collision search algorithms like Ambainis for collision-resistant hash functions?

I just stumbled onto a series of 2017 papers about applying the Ambainis quantum collision-finding algorithm to hash functions. (disclaimer: I haven't read all of them in full yet): Post-quantum ...
4
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4answers
816 views

What telltale signs would indicate that quantum computers are about to become dangerous to classical cryptography?

What would be telltale signs that quantum computers become imminent and sizable danger to classical cryptography in commercial applications ? Make classical cryptography consist of symmetric ...
2
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1answer
247 views

Why is the number of qubits used in Shor's factoring algorithm so high?

When preparing the initial state of the algorithm to factor $n$ he computes $q = 2^l$ such that $n^2 \leq q < 2n^2$. The first register then contains $l$ qubits. Why does this need to be so high. ...
4
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1answer
184 views

it is possible to use quantum algorithm search (Grover's algorithm) for new searching strategies for differential and linear attacks

I am trying to use Grover's algorithm to find Differential characteristic of Feistel and SPN structures block ciphers. basically, which is Finding a good differential characteristic with high ...
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1answer
257 views

Real world performance of (still theoretical) Grover's Algorithm

Grover's Algorithm is a quantum algorithm for searching "black box" functions and could be used to reduce the search space for things like symmetric ciphers and hashes by as much as half (quadratic ...
2
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0answers
362 views

XTS-AES-128 and Grover's algorithm

AES-128 is considered weak against quantum computers because Grover's algorithm effectively halves its key length to unacceptable 64 bits. XTS-AES-128 as described in IEEE 1619-2007 doubles key ...
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150 views

Space complexity of quantum collision search?

Is there a known way to reduce the space complexity of quantum collision search (PDF) beyond what is offered by the built-in time-space tradeoff, while keeping the time complexity significantly below ...