Questions tagged [key-distribution]
For questions about quantum key distribution (QKD). It is a secure communication method which implements a cryptographic protocol involving components of quantum mechanics. (Wikipedia) In case it's also a question about quantum-cryptography, use the [cryptography] tag along with this.
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Role of eavesdroppers in B92 of phase modulation
I have a question about the phase modulation scheme described in Bennett et al. (1992). In figure 2 of this paper, it says
Source at left supplies the coherent pulse of M>1 expected photons ...
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Choosing E91/BB84 basis states and angles
What is the logic for choosing the angles of E91 for the specific basis states? I have noticed a variety of different angles being used as the basis states for Alice and Bob. Would adding more basis ...
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Role of Intensity Modulator's Extinction Ratio on transmitter side in COW/DPS QKD using Weak Coherent Pulses
What is the role of having a high extinction ratio (30-40 dB) for the intensity modulator on the transmitter side in COW/DPS QKD using Weak Coherent Pulses, when ultimately the pulses have to be ...
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Vmod in Gaussian Modulated QKD
In the paper "Continuous-Variable Quantum Key Distribution with Gaussian Modulation – The Theory of Practical Implementations" by Fabian Laudenbach, there's a distinction between the ...
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Why does entanglement of 3 qubits break this?
Another user asked about the Ekert Quantum Key Distribution protocol: Alice and Bob each randomly choose one of three bases separated by $120^{\circ} $ in which to measure, and then later compare the ...
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Which protocol does the Qiskit textbook use for Quantum Key Distribution?
I've worked through a couple different protocols for quantum key distribution, but when I look at the Qiskit textbook on this page I am unable to determine which one was used in this lesson. If anyone ...
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What type of attack(individual attack, collective attack, coherent attack) is a PNS attack?
While studying the attack method of QKD, I found that intercept and resend attack is an example of an individual attack.
What are the examples of collective attack and coherent attack?
Specifically, ...
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E91 probability of wrong conclusion of eavesdropper
If I use E91 protocol for QKD, with n bits exchanged, what is the probability that you think there is an eavesdropper but there really isn't one or the opposite you think there is no eavesdropper but ...
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In the E91 protocol, how can Alice and Bob detect Eve if she waits to measure until A&B publish their bases?
I'm studying the E91 protocol. Suppose Eve has a qubit entangled with Alice's and Bob's qubits.
I understand how Alice and Bob can detect Eve if Eve measures before A&B by testing Bell's ...
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BB84 Protocol doubt
I was studying BB84 protocol from lecture notes by John Watrous. I had some doubts which i thought of asking. Here is the protocol.
Alice prepares strings $x=(01110100)$ and $y=(11010001)$. based on ...
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Why is Measurement Device Independent (MDI) Quantum Key Distribution (QKD) truly MDI?
This is a repost from a question I posted in the physics stack exchange
I am having a hard time understanding why MDI-QKD is truly measurement device independent. My current vision is that Charlie (...
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Doubt in CSS error correction step
At the end of page 3 in Simple proof of security of the BB84 QKD, the following equation (equation 4) is given :
$$
\begin{array}{r}
\frac{1}{2^{n}\left|C_{2}\right|} \sum_{z}\left[\sum_{w_{1}, w_{2} ...
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Doubt in Simple proof of Security of the BB84 QKD
I am not able to understand an argument from Simple proof of Security of the BB84 QKD; I need your help. In page 2 it is mentioned that "Alice can measure her half of the encoded EPR pairs before ...
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Major Security proofs available for Device-Independent QKD
I've lately started working on a DI-QKD project. I've started looking into Vazirani and Vidick's PRL paper on Device-Independent QKD security proof. It's proving to be quite time-consuming for me to ...
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Can we do error correction for entangled particles?
There are several quantum error correction techniques, such as 3-qubit bit-flip code, and Shor’s 9-qubit code. 3-qubit bit-flip code is a straightforward technique for correcting a single error (...
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Understanding the (2,3) threshold quantum secret sharing scheme in Cleve et al. 1999
In the paper "How to share quantum secret" by R.Cleve et al (arxiv).
There is an example of secret sharing using qutrit in a (2,3) threshold scheme.
$$\alpha\vert0\rangle+\beta\vert1\rangle+\...
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Average secret key rate calculation
I am working on a problem related to average secret key rate calculation in satellite quantum key distribution (QKD). The problem is similar to a paper on arXiv:1712.09722 (P. No. 21).
In a single ...
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Quantum bit error rate
I am trying to understand the quantum key distribution and Quantum Bit Error Rate (QBER). I have question: Why is the QBER given by the average of the diagonals of the crosstalk matrix? Why the need ...
Rasha rashed
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What is meant with "reconciliation" in CV QKD?
I am working on a paper about Continuous Variable QKD. (https://arxiv.org/abs/1711.08500v2)
I read about direct and reverse reconciliation in this paper. I don't understand what exactly Reconciliation ...
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The Methodology of Quantum Key Distributions Systems
While reading an answer in Cryptography.SE I saw this
As for security, that's one possible way to perform Quantum Key Distribution, another real thing. However, most current QKD systems sold today do ...
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How are Franson Interferometers used to prove security in Photonic QKD Experiments?
I am currently reading this paper about Quantum Key Distribution Protocols which use Franson Interferometers to secure against eavesdroppers. I am having trouble understanding how the interferometers ...
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What is the intuition behind the following entanglement distillation protocol for continuous variable systems?
The protocol is:
We start with a supply
of identically prepared bipartite non-Gaussian states. The overall protocol then amounts to an iteration of the following
basic steps.
The states will be mixed ...
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In the BICONF information reconciliation protocol for QKD: should I also run BINARY on the complementary bits subset?
The descriptions of the BICONF information reconciliation protocol in the literature appear to be inconsistent.
All descriptions agree that in each iteration Alice and Bob should select a random ...
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BB84 and B92 protocols: what is maximum and minimum bits that Alice and Bob might agree on?
Say Alice wants to transmit a 10-bit key.
For the BB84 protocol, if we assume that Alice and Bob use the same basis to encode and decode 6 qubits (and different ones for the other 4), then what ...
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What authentication protocol to use for BB84 and other QKD protocols?
Just like other classical and quantum key distribution protocols, BB84 is vulnerable to "man"-in-the-middle attacks, where Eve pretends to be Bob to Alice, and Eve pretends to be Alice to ...
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In what ways can qubits be used for applications that do not require entanglement?
Many good questions on this site have explored how entanglement lies at the boundary between the quantum world and the classical. For example in computational speedups, or teleportation or superdense ...
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Counting channel uses of the lossy bosonic channel or definition of channel uses
The PLOB-bound ("Fundamental Limits of Repeaterless Quantum Communications") gives an asymptotic upper bound on the secret-key rate per used lossy bosonic channel.
However, I'm not sure how to count ...
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What role do Hecke operators and ideal classes perform in “Quantum Money from Modular Forms?”
Cross-posted on MO
The original ideas from the 70's/80's - that begat the [BB84] quantum key distribution - concerned quantum money that is unforgeable by virtue of the no-cloning theorem. A ...
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What is the difference between quantum key distribution and quantum key exchange?
Both the words 'Quantum Key Distribution' and 'Quantum Key Exchange' are used in quantum cryptography in the problem of a secure key distribution for encryption/decryption between parties. There are ...
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Implementing BB84 protocol with easily-obtained consumer hardware
Following on from my question on educational quantum computing toys, I was wondering whether it is possible to implement the BB84 key distribution protocol with easily-obtained consumer hardware - ...
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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 ...
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Why is the efficiency of Ekert 91 Protocol 25%?
In Cabello's paper Quantum key distribution without alternative measurements, the author said "the number of useful random bits shared by Alice and Bob by transmitted qubit, before checking for ...
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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 ...
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