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Questions tagged [cryptography]

For questions about cryptography as it relates directly to quantum computing. Not for general cryptographic methods.

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1answer
32 views

Lattice based cryptography vs BB84

Am I correct in thinking that post-quantum cryptography such as lattice-based solutions run on classical computers are resistant to quantum attacks (as opposed to RMS), whereas quantum key ...
3
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1answer
78 views

How many qubits does it take to break a 10 characters password?

Let's assume we developed a hashcat-like programs for quantum computer. How many qubits we need to find the correct hash (WPA, MD5,...) from a 10 characters password make from upper, lower & ...
8
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1answer
79 views

How many bits do Alice and Bob needs to compare to make sure the channel is secure in BB84?

I was trying to self-study qmc by reading the Quantum Computing A Gentle Introduction book, in section 2.4 it talks about the quantum key distribution protocol BB84. After (I thought) I understood it ...
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0answers
28 views

Are non-secret-based quantum money mini-schemes susceptable to Jogenfors' “reuse attack?”

Aaronson and Christiano call public-key or private-key quantum mini-schemes $\mathcal M$ secret-based if a mint works by first uniformly generating a secret random classical strings $r$, and then ...
6
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1answer
123 views

Can quantum money be reliably “burned?”

One of the novel features of Bitcoin and other cryptocurrencies is that coins can be irrefutably "burned" or destroyed, by creating a transaction to send the money to a junk burn address. Thinking ...
6
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2answers
118 views

What measures can be taken against attacks on cryptosystems by quantum computers other than just classifying research?

If quantum computers advance to the point where they can defeat RSA, DSA, SHA (and really all existing classical public key encryption or and authentication) then it appears that it would be ...
7
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1answer
67 views

What classical public key cryptography protocols exist for which hacking is QMA complete or QMA hard?

Such a public key cryptosystem would be "quantum safe" in the sense that quantum computers cannot efficiently solve QMA hard problems.
9
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2answers
108 views

How to justify post quantum encryption security?

Is there some definition or theorem about what a quantum computer can achieve from which post-quantum cryptographic schemes (eg lattice cryptography, but not quantum cryptography) can justify their ...
8
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0answers
148 views

Time Entangled Quantum Blockchain

This answer cites a paper[$\dagger$] which purposes a quantum blockchain using entanglement in time. "The weakness is that the research only presents a conceptual design." - QComp2018 How could a ...
16
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2answers
2k views

Is quantum cryptography safer than classical cryptography?

Quantum computing allows us to encrypt information in a different way compared to what we use today, but quantum computers are much more powerful than today's computers. So if we manage to build ...
6
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1answer
82 views

BB84 Protocol Alice Choice to Bob

The image is taken from this link. Here Alice is using random bases to encode 0 or 1. After the process is completed, Bob has similarly polarized photons as Alice. These polarization can be any of ...
4
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2answers
87 views

'Rectilinear' and 'Diagonal' Basis in BB84 Protocol

A lot of the tutorials on BB84 protocol talks about these two measurement bases, 'Rectilinear' or 'Vertical-Horizontal' and 'Diagonal'. I understand that it is possible to create a physical device ...
8
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3answers
120 views

How can we reliably know if a key size is still safe to use as new quantum computers are created?

I've heard that quantum computers pose a major threat to 1024 bit and possibly even 2048 bit RSA public-private key cryptography. In the future however, bigger size keys will probably become at risk ...
11
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2answers
209 views

Rigorous security proof for Wiesner's quantum money

In his celebrated paper "Conjugate Coding" (written around 1970), Stephen Wiesner proposed a scheme for quantum money that is unconditionally impossible to counterfeit, assuming that the issuing bank ...
7
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1answer
230 views

How would Blockchain technologies change to survive a post-quantum world? [closed]

Reading this entertaining piece of a QC enthusiast mining bitcoins with a Quantum Computer (although efficiently mining bitcoins with the current state of QCs is far-fetched, it is quite possible to ...
4
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0answers
74 views

Will post quantum crypto come soon enough? [closed]

The main reason to start with Post Quantum Crypto (PQC) right now is because creating strong crypto, good implementation and accepted standards takes very long. Right now, most PQC is in the 'crypto' ...
17
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1answer
205 views

Quantum Bitcoin Subdivision

Background Recently I was reading the article "Quantum Bitcoin: An Anonymous and Distributed Currency Secured by the No-Cloning Theorem of Quantum Mechanics" which demonstrates how a quantum bitcoin ...
12
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2answers
197 views

Advantage of quantum key distribution over post-quantum cryptography

Post-quantum cryptography like lattice-based cryptography is designed to be secure even if quantum computers are available. It resembles currently employed encryptions, but is based on problems which ...
11
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1answer
170 views

Are there any encryption suites which can be cracked by classical computers but not quantum computers?

Are there any encryption suites that can be cracked by usual computers or super computers, but not quantum computers? If that's possible, what assumptions will it depend on? (Factorizing big numbers, ...
16
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2answers
202 views

Blind Quantum Computing Generic Structure Variable Selection

Background Recently I came upon a research article entitled Experimental Demonstration of Blind Quantum Computing. Within this research article, the scientists claimed that - through the proper ...
15
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2answers
177 views

How is quantum cryptography different from cryptography used nowadays?

Recent researches indicate that quantum algorithms are able to solve typical cryptology problems much faster than classic algorithms. Have any quantum algorithms for encryption been developed? I'm ...
34
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4answers
786 views

Is it possible for an encryption method to exist which is impossible to crack, even using quantum computers?

Quantum computers are known to be able to crack in polynomial time a broad range of cryptographic algorithms which were previously thought to be solvable only by resources increasing exponentially ...