Comment on 'Eavesdropping on the ping-pong communication protocol'

Improved Wójcik's Eavesdropping Attack on Ping-Pong Protocol Without Eavesdropping-Induced Channel Loss

The eavesdropping scheme proposed by Wójcik [Phys. Rev. Lett. {\bf 90},157901(2003)] on the ping-pong protocol [Phys. Rev. Lett. {\bf 89}, 187902(2002)] is improved by constituting a new set of attack operations. The improved scheme has a zero eavesdropping-induced channel loss and produces perfect anticorrelation. Therefore, the eavesdropper Eve can safely attack all the transmitted bits and the eavesdropping information gain can always exceed the legitimate user's information gain in the whole domain of the quantum channel transmission efficiency $η$, i.e., [0,100%]. This means that the ping…

General individual attack on the ping-pong protocol with completely entangled pairs of qutrits

The general individual (non-coherent) attack on the ping-pong protocol with completely entangled pairs of three-dimensional quantum systems (qutrits) is analyzed. The expression for amount of the eavesdropper's information as functions from probability of attack detection is derived. It is shown, that the security of the ping-pong protocol with pairs of qutrits is higher the security of the protocol with pairs of qubits. It is also shown, that with the use by legitimate users in a control mode two mutually unbiased measuring bases the ping-pong protocol with pairs of qutrits, similar to the pr…

On Ping-Pong protocol and its variant

We discuss the Ping-Pong protocol which was proposed by Bostroem and Felbinger. We derive a simple trade-off inequality between distinguishability of messages for Eve and detectability of Eve for legitimate users. Our inequality holds for arbitrary initial states. That is, even if Eve prepares an initial state, she cannot distinguish messages without being detected. We show that the same inequality holds also on another protocol in which Alice and Bob use one-way quantum communication channel twice.

The security of Ping-Pong protocol

Ping-Pong protocol is a type of quantum key distribution which makes use of two entangled photons in the EPR state. Its security is based on the randomization of the operations that Alice performs on the travel photon (qubit), and on the anti-correlation between the two photons in the EPR state. In this paper, we study the security of this protocol against some known quantum attacks, and present a scheme that may enhance its security to some degree.

Secure Direct Communication based on Ping-pong Protocol

Communication security with quantum key distribution has been one of the important features of quantum information theory. A novel concept of secured direct communication has been the next step forward without the need to establish any shared secret key. The present paper is based on the ping-pong protocol with three particle GHZ state as the initial state where the receiver can simultaneously receive information from two parties. Possible eavesdropping on the travelling particle has been examined.

Improving the capacity of the ping-pong protocol

We present a quantum communication protocol which keeps all the properties of the ping-pong protocol [Phys. Rev. Lett. 89, 187902 (2002)] but improves the capacity doubly as the ping-pong protocol. Alice and Bob can use the variable measurement basises in control mode to detect Eve's eavesdropping attack. In message mode, Alice can use one unitary operations to encode two bits information. Bob only needs to perform a Bell type measurement to decode Alice's information. A classical message authentification method can protect this protocol against the eavesdropping hiding in the quantum channel …

Eavesdropping on the "Ping-Pong" Quantum Communication Protocol Freely in a Noise Channel

We introduce an attack scheme for eavesdropping the ping-pong quantum communication protocol proposed by Bostr$\ddot{o}$m and Felbinger [Phys. Rev. Lett. \textbf{89}, 187902 (2002)] freely in a noise channel. The vicious eavesdropper, Eve, intercepts and measures the travel photon transmitted between the sender and the receiver. Then she replaces the quantum signal with a multi-photon signal in a same state, and measures the photons return with the measuring basis with which Eve prepares the fake signal except for one photon. This attack increase neither the quantum channel losses nor the erro…

Ping-pong quantum key distribution with trusted noise: non-Markovian advantage

The ping-pong protocol adapted for quantum key distribution is studied in the trusted quantum noise scenario, wherein the legitimate parties can add noise locally. For a well-studied attack model, we show how non-unital quantum non-Markovianity of the added noise can improve the key rate. We also point out that this noise-induced advantage cannot be obtained by Alice and Bob by adding local classical noise to their post-measurement data.

Eavesdropping on the "ping-pong" type quantum communication protocols with invisible photon

The crucial issue of quantum communication protocol is its security. In this paper, we show that all the deterministic and direct two-way quantum communication protocols, sometimes called ping-pong (PP) protocols, are insecure when an eavesdropper uses the invisible photon to eavesdrop on the communication. With our invisible photon eavesdropping (IPE) scheme, the eavesdropper can obtain full information of the communication with zero risk of being detected. We show that this IPE scheme can be implemented experimentally with current technology. Finally, a possible improvement of PP communicati…

Game-theoretic perspective of Ping-Pong Protocol

We analyse Ping-Pong protocol from the point of view of a game. The analysis helps us in understanding the different strategies of a sender and an eavesdropper to gain the maximum payoff in the game. The study presented here characterizes strategies that lead to different Nash equilibriums. We further demonstrate the condition for Pareto optimality depending on the parameters used in the game. Moreover, we also analysed LM05 protocol and compared it with PP protocol from the point of view of a generic two-way QKD game with or without entanglement. Our results provide a deeper understanding of …

Security of modified Ping-Pong protocol in noisy and lossy channel

The "Ping-Pong" (PP) protocol is a two-way quantum key protocol based on entanglement. In this protocol, Bob prepares one maximally entangled pair of qubits, and sends one qubit to Alice. Then, Alice performs some necessary operations on this qubit and sends it back to Bob. Although this protocol was proposed in 2002, its security in the noisy and lossy channel has not been proven. In this report, we add a simple and experimentally feasible modification to the original PP protocol, and prove the security of this modified PP protocol against collective attacks when the noisy and lossy channel i…

How Secure Are Two-Way Ping-Pong and LM05 QKD Protocols under a Man-in-the-Middle Attack?

We consider a man-in-the-middle attack on two-way quantum key distribution ping-pong and LM05 protocols in which an eavesdropper copies all messages in the message mode, while being undetectable in the mode. Under the attack there is therefore no disturbance in the message mode and the mutual information between the sender and the receiver is always constant and equal to one and messages copied by the eavesdropper are always genuine. An attack can only be detected in the control mode but the level of detection at which the protocol should be aborted is not defined. We examine steps of the prot…

Increasing the security of the ping-pong protocol by using many mutually unbiased bases

In this paper we propose an extended version of the ping-pong protocol and study its security. The proposed protocol incorporates the usage of mutually unbiased bases in the control mode. We show that, by increasing the number of bases, it is possible to improve the security of this protocol. We also provide the upper bounds on eavesdropping average non-detection probability and propose a control mode modification that increases the attack detection probability.

Deterministic Secure Direct Communication Using Ping-pong protocol without public channel

Based on an EPR pair of qubits and allowing asymptotically secure key distribution, a secure communication protocol is presented. Bob sends either of the EPR pair qubits to Alice. Alice receives the travel qubit. Then she can encode classical information by local unitary operations on this travel qubit. Alice send the qubit back to Bob. Bob can get Alice's information by measurement on the two photons in Bell operator basis. If Eve in line, she has no access to Bob's home qubit. All her operations are restricted to the travel qubit. In order to find out which opeartion Alice performs, Eve's op…

Eavesdropping on the Bostroem-Filbinger Communication Protocol in Noisy Quantum Channel

We show an eavesdropping scheme on Bostr\UNICODE{0xf6}m-Felbinger communication protocol (called ping-pong protocol) [Phys. Rev. Lett. 89, 187902 (2002)] in an ideal quantum channel. A measurement attack can be perfectly used to eavesdrop Alice's information instead of a most general quantum operation attack. In a noisy quantum channel, the direct communication is forbidden. We present a quantum key distribution protocol based on the ping-pong protocol, which can be used in a low noisy quantum channel. And we give a weak upper bound on the bit-error ratio that the detection probability $d$ sho…

A general scheme for information interception in the ping pong protocol

The existence of an undetectable eavesdropping of dense coded information has been already demonstrated by Pavičić for the quantum direct communication based on the ping-pong paradigm. However, a) the explicit scheme of the circuit is only given and no design rules are provided, b) the existence of losses is implicitly assumed, c) the attack has been formulated against qubit based protocol only and it is not clear whether it can be adapted to higher dimensional systems. These deficiencies are removed in the presented contribution. A new generic eavesdropping scheme built on a firm theoretical …

Deterministic Quantum Key Distribution Using Gaussian-Modulated Squeezed States

A continuous variable ping-pong scheme, which is utilized to generate deterministically private key, is proposed. The proposed scheme is implemented physically by using Gaussian-modulated squeezed states. The deterministic way, i.e., no basis reconciliation between two parties, leads a two-times efficiency comparing to the standard quantum key distribution schemes. Especially, the separate control mode does not need in the proposed scheme so that it is simpler and more available than previous ping-pong schemes. The attacker may be detected easily through the fidelity of the transmitted signal,…

量子场论中的超光速局域操作：乒乓球检验

Superluminal local operations in quantum field theory: A ping-pong ball test

该研究证明量子场论与经典相对论场论中均存在能引发局域区域内超光速效应的瞬时空间旋转类局域操作，表明相关不可能测量场景并非量子场论独有。

Deterministic Secure Direct Communication Using Mixed state

We show an improved ping-pong protocol which is based on the protocol showed by Kim Bostrom and Timo Felbinger [Phys. Rev. Lett. 89, 187902 (2002); quant-ph/0209040]. We show that our protocol is asymptotically secure key distribution and quasisecure direct communication using a single photon resource. And this protocol can be can be carried out with great efficiency and speed using today's technology.

Security of a High Dimensional Two-Way Quantum Key Distribution Protocol

Two-way quantum key distribution protocols utilize bi-directional quantum communication to establish a shared secret key. Due to the increased attack surface, security analyses remain challenging. Here we investigate a high-dimensional variant of the Ping Pong protocol and perform an information theoretic security analysis in the finite-key setting. Our methods may be broadly applicable to other QKD protocols, especially those relying on two-way channels. Along the way, we show some fascinating benefits to high-dimensional quantum states applied to two-way quantum communication.

It Does Not Follow. Response to "Yes They Can! ..."

This a response to "Yes They Can! ..." (a comment on [5]) by J.S. Shaari et al. [9]. We show that the claims in the comment do not hold up and that all the conclusions obtained in [5] are correct. In particular, the two considered kinds of two-way communication protocols (ping-pong and LM05) under a quantum-man-in-the-middle (QMM) attack have neither a critical disturbance (D), nor a valid privacy amplification (PA) procedure, nor an unconditional security proof. However, we point out that there is another two-way protocol which does have a critical D and a valid PA and which is resistant to a…