Questions tagged [quantum-cryptography]

Quantum cryptography describes the use of quantum mechanical effects to perform cryptographic tasks. This is not to be confused with quantum computing or cryptanalysis techniques such as Shor's algorithm.

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New quantum attack on lattices (or Shor strikes again)?

Lior Eldar and Peter W. Shor published a paper on arXiv.org in which they present a new quantum algorithm against a variant of BDD. They claim that their new algorithm can efficiently solve the ...
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Applicability of IBM's projected 50-qubit quantum computer Q to cryptanalysis?

IBM announced Q, a project for a 50-qubit universal quantum computer, according to the press realease. Here is more PR spin, and the research sub-page. What would be the applicability of that to ...
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What makes Quantum Cryptography secure?

This is my current understanding of how Quantum Cryptography works: (The first bit is Quantum Key Distribution) Alice sends a beam of photons to Bob through a quantum channel such as an optical fiber....
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In layman's terms, how does Shor's algorithm work?

I've just been reading up on Shor's algorithm, and I find it both fascinating and baffling. I don't really understand much about it, other than that it can factor semiprimes in polynomial time. Could ...
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What does a “real” quantum computer need for cryptanalysis and/or cryptographic attack purposes?

The cryptographic world has been buzzing the word "quantum" for a while now (even the NSA is currently preparing itself for a post-quantum crypto world) and quantum-related hardware engineering is ...
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How effective is quantum computing against elliptic curve cryptography?

I've been reading the Wikipedia page on Elliptic-Curve Cryptography and I came across the following. in August 2015, the NSA announced that it plans to replace Suite B with a new cipher suite due ...
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Dice vs quantum random number generator

I recently championed quantum key distribution networks. This has led me to also question quantum random number generators. It appears that randomness is randomness, even if made by custom quantum ...
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Qubit / Qutrit - Is there a theoretical limit on how many orthogonal states a quantum bit has?

Seems like a quantum bit with $3$ orthogonal quantum states is called a qutrit - and they have been demonstrated practically. In comparison with $n$ qubits that have ~$2^{n}$ states, these have ~$3^{n}...
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Is full Homomorphic encryption quantum resistant?

Since most of our asymmetric encryption algorithms are going to be out-of-date in a couple of year due to Shor's algorithm, I was wondering about the future of FHE schemes. I have found this paper, ...
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What role plays Quantum Fourier Transformation in Shor's integer factorization algorithm?

I cannot seem to understand the role or goal of Quantum Fourier Transformation in Shor's integer factorization algorithm. Is it used to collapse all quantum states into one, in which it has a factor ...
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What is the difference between Shor's algorithm for factoring and Shor's algorithm for logarithm

There is a paper from Peter W. Shor from 1994: http://www.csee.wvu.edu/~xinl/library/papers/comp/shor_focs1994.pdf "Algorithms for Quantum Computation: Discrete Logarithms and Factoring", and I have a ...
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Is quantum key distribution safe against MITM attacks too?

i read this recently: http://www.newscientist.com/article/dn12786-quantum-cryptography-to-protect-swiss-election.html and some parts of this: http://en.wikipedia.org/wiki/Quantum_key_distribution ...
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Can Shor's algorithm compromise RSA when both the public and private key are secret?

If RSA is to create a public private key pair and encryption is performed on plain test P to create cipher text C, given P and C could Shor's algorithm be used to find either of the public and private ...
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Are there any applications of Quantum Computation to Cryptography? (besides Cryptanalysis)

I know that people may be yelling "of course!" at the title of the question, but my concern is not about how to construct quantum-resistant primitives, but rather how to use the power of quantum ...
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Are hash functions strong against quantum cryptography and/or independent enough of mathematics?

I work on ethereum and other blockchain technologies. And seeing that quantum pc's are someday going to see the light I have some questions / doubts. I was wondering if hash functions are strong ...
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What does “a 15360-bit RSA key is the equivalent to a 256-bit symmetric key” mean?

NIST key management guidelines suggest that 15360-bit RSA keys are equivalent in strength to 256-bit symmetric keys. If a 15360-bit RSA key is the equivalent to a 256-bit symmetric key, does that mean ...
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Quantum key distribution simulation

I'm looking for a simulation of the Quantum Key Distribution protocol. Does anyone here have one that they could recommend?
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Could quantum computers “break” symmetric crypto-systems (e.g. AES)?

These days I'm reading about quantum computing and quantum cryptography which I've found extremely interesting. Well, I also read some blog posts of Bruce Schneier talking about how quantum computers ...
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Generating a random number using a quantum computer

I have been looking into the creation of truly random numbers using a quantum computer, but I have been having trouble with finding resources on this problem. Is it possible to create a truly random ...
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How do Latin squares relate to quantum cryptography?

About ten years ago I became interested in Latin squares. A friend who was at the Clay Institute at the time mentioned that applications for Latin squares were exploding, and that they were being ...
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How important is hardware based crypto in Quantum-safe TLS in mobile devices?

Microsoft Research published an approach to Quantum-safe TLS here, namely RLWE-ECDSA-AES128-GCM-SHA256. One highlight is that when it's used with ECC, there is only a slight performance hit. ...
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Quantum key exchange skepticism/confusion

I was hoping somebody could explain some issues I have with quantum key exchange that I don't quite understand. I've read bits and pieces about BB84 but I'm sure my questions probably apply to other ...
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Advantages of RSA / EC against QC attacks

We know that both the RSA and ECC algorithms are vulnerable against attacks using (future) Quantum Computing (QC). Are there however any advantages of choosing one algorithm over the other? As an ...
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What does Shor's algorithm tell us about the complexity class of RSA and the DLP?

If quantum computers operate in BQP and (using Shor's algorithm) they are able to factor large integers and break the discrete log problem, what does that tell us about the complexity class of these ...
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Quantum Random Oracle Model

Let $\mathcal{H} : \{0,1\}^* \rightarrow \{1,\cdots,n\}$ be a hash function. I believe that in the Random Oracle model, the probability that an adversary $A$ can find a message $M$ such that $\...
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Blind quantum computing and fully homomorphic encryption

I am somewhat familiar with current research on fully homomorphic enryption schemes and their possible application to Cloud computing. I've just noticed (somewhat late) that a marketing-savvy group ...
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What authentication techniques can be used by QKD Systems?

As it is well known that QKD systems are prone to simple MITM attacks… what authentication techniques are being used in QKD to prevent those attacks in practice?
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Is E91 safer than BBM92?

I would like to compare the security of these two QKD protocols which both use entangled photons that are distributed between the users Alice and Bob. In the case of E91, the photon is measured ...
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Any implication of a Yale result to security of quantum cryptology?

Quantum key distribution depends, if I don't err, on (irreversible) damages done by MITM's measurements on qbits. Now news.yale.edu/2013/01/11/new-qubit-control-bodes-well-future-quantum-computing ...
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How does quantum encryption work?

There has been a lot of buzz about quantum computing especially with D-Wave breaking the limits each month. I have basic knowledge about cryptography with an introductory course in quantum computing. ...
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Quantum key distribution and the one-time pad

Why is QKD usually associated with OTP ? QKD is about key distribution, where as OTP is about using key as long as message to get perfect secrecy, can any one explain how they are related ?
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Small Quantum Signatures - Reality check needed

I've been thinking a bit lately about how to get quantum resistant signatures fast and (relatively) small. One idea I've been keen on exploring is finding a crypto PRNG that allows fast-forwarding, e....
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great discovery in the field of elliptic curves cryptography?

Prof. Adi Shamir says in The Cryptographers' Panel 2016: i think that NSA has made a great discovery in the field of elliptic curves cryptography and NSA wants to avoid the increased use and ...
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Understanding Quantum Key Distribution

I have watched dozens of videos on YouTube talking about Quantum Cryptography and how the BB84 algorithm works. However none of them bothered himself to explain how quantum key exchange process works ...
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what is the motivation behind quantum key distribution with Continuous variable?

Quantum Key Distribution protocol is a technique that allow two parties to share common secret key for cryptographic purpose and defined as being secure, by definition. But I am still wondering what ...
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Is quantum cryptography unbreakable?

People always say that "there is no such thing as unbreakable crypto!" In most cases they are right. AES, RC4, RSA, C25519, DH, .... are all cryptographic algorithms which are crackable (with extreme ...
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Practical quantum attacks on AES - Is AES-128 used in a block mode vulnerable to attack using quantum algorithms

Can Grover's (or similar) algorithm be used to attack AES-128 when used in cipher modes like CTR? It seems like the answer is no... Also I have a similar question for SHA256 when used for a MAC. It ...
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Can quantum computers break quantum cryptography?

I happened to learn that encryption by quantum cryptography would be impossible to break as it's state changes the instant of an eavesdropping event(by non-quantum systems) occurs. But I'm not sure if ...
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Cryptocurrency for quantum computers that is physically impossible to double-spend?

Could a cryptocurrency running (at least partially) on a quantum computer (and/or on a quantum network) be developed in which it is physically impossible to double-spend? In other words, a coin in ...
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Is quantum randomness different to conventional randomness?

I've been reading a question regarding the uses of quantum computing. There is a broad theme throughout the answers that seems to suggest that randomness generated via quantum means is somehow better ...
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Need an XL Algorithm example

could anyone give me a small example with actual numbers and variables over a finite field of how the XL algorithm is used to solve overdetermined systems? And the steps involved. I understand the ...
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How can Shor's Algorithm be applied to ECC?

I have not found a specific answer to this question on here. Shor's algorithm can be used to factorize a large (semi)prime $N$ by reducing the task to period-finding of a function $f(x)=x^a$ mod $N$. ...
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BB84 - Bits needed to detect Eve's presence

From Quantum Computing: A Gentle Introduction: In the BB84 protocol, how many bits do Alice and Bob need to compare to have a 90% chance of detecting Eve's presence? I am having some trouble ...
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What are the current known weaknesses/attacks on quantum key distribution?

I am writing a paper on the implementation of QKD in the future. I want to know if there are any viable attacks on the BB84 protocol or QKD in general? I know of the Photon Number Splitting attack or ...
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Quantum Cryptography Used in a messaging application

Is it possible to create a messaging application and apply a quantum cryptography technique to encrypt the messages between two parties within the application?
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Why a Unitary Matrix in Quantum Cryptography?

I've read that in Quantum circuits the matrix that encodes the transformation has to be unitary. I understand that it must preserve the norm of the resulting qubit, but what is the intuition behind it?...
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Is using quantum computing to break passwords non-sense?

I understand the concept of 'trying all possibilities at once' but can anyone explain this with respect to the fact that my PC only accepts one password at a time? There's no input field that accepts ...
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Shor's algorithm for elliptic curve discrete logarithm problem

Could you write Shor's algorithm for solving the discrete logarithm problem and how it could apply to elliptic curves in a few, easy to understand steps? I have a basic understanding of quantum ...
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What kind of Quantum cryptography technology(protocols) can be used for Mobile Ad hoc networks(MANETS)?

Typically ad hoc networks do not have a proper infrastructure and the routing is done only through the base stations which are connecting a wired and wireless network. Does quantum cryptography ...
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Quantum algorithm encrypting classical data

Are there schemes for encrypting classical ciphertext using quantum algorithms? Specifically, if a public key system exists for classical data, and classical ciphertexts, can this scheme be ...