Two-party Quantum Key Agreement Research Articles

Authenticated quantum key agreement based on cluster states against collective noise

Quantum key agreement (QKA) is an important branch of quantum cryptography. Particles are easily affected by noise in quantum channel transmission, which provides a cover for eavesdropper Eve to attack maliciously and eventually leads to the protocol failure. In this paper, based on the properties of four-particle cluster states and their entanglement swapping, two authenticated two-party QKA protocols that can resist collective noise (collective-dephasing noise and collective-rotation noise) by using CZ, CNOT, and Pauli operations are designed, respectively. Besides, both parties can authenticate each other’s identities, which makes our protocol more secure. In addition, security analysis shows that these two protocols can resist various attacks from inside and outside, such as participant attacks and entangle-measure attacks.

Two-party Quantum Key Agreement with Six-particle Entangled States Against Collective Noise

Two-party Quantum Key Agreement with Six-particle Entangled States Against Collective Noise

Improvements on new quantum key agreement protocol with five-qubit Brown states

Recently, Cao et al. [Mod. Phys. Lett. A 34, 1950332 (2019)] presented a two-party quantum key agreement scheme using the five-qubit Brown states and the decoy protocol. They also extended their scheme to the multiparty case, and it was compared with existing works. The authors also introduced the security analysis that proves the security of their protocol against outsider and insider attacks. However, this work shows that the quantum Cao et al. [Mod. Phys. Lett. A 34, 1950332 (2019)] protocol fails to fulfill one of the most significant conditions of the quantum key agreement, which is fairness. The computed final key by the users does not have the same level of security, and the protection of users’ private data is not maintained equally. Finally, an improved version of Cao et al.’s protocol has been suggested.

Cryptanalysis and Improvements on Quantum Key Agreement Protocol Based on Quantum Search Algorithm

Recently, Huang et al. (2021) presented a quantum key agreement schemeto securely negotiate on a secret key employing the properties of a quantumsearch algorithm. First, the authors proposed the two-party quantum key agreement, and then they extended their work to the three-party case. Huang et al.‘s protocol employs the unitary operation and single-particle measurements to negotiate on a secret key without using complex quantum technologies such as quantum memory or entangled quantum particles. The authors claimed that their protocol is secure and efficient. However, this work shows that Huang et al.‘s protocol has a significant pitfall, where the private key of one user could be easily leaked to the attackers. Hence, the properties of security and fairness are not achieved. Accordingly, thetwo-party and three-party of Huang et al.’s protocol have been reviewed, and an improvementto address the shortcoming is suggested.

Quantum Key Agreement Protocol Based on Quantum Search Algorithm

Quantum key agreement (QKA) and quantum search algorithm (QSA) are two important branches in quantum topic. The former asks all participants to negotiate the agreement key equally, and none of them can fully determine the agreement key. The latter is used to provide an acceleration in searching the marked item in an unsorted database. To date, several QKA schemes based on either BB84 or entangled states have been proposed, the QKA protocol based on QSA is rare, only exists one multi-party QKA (MQKA) protocol based on QSA. In this paper, on the basis of the properties of Grover’s QSA, the first two-party quantum key agreement protocol based on quantum search algorithm known as Grover’s algorithm is proposed. The participants transmit a two-particle quantum state sequence directly by inserting decoy photons randomly. The initial-prepared two-particle quantum states are easy to be prepared with current technology. Moreover, there is no swapping entanglement technology used in this protocol, it only needs unitary operations and single-particle measurements. Compared with the existing two-party QKA protocol, the proposed QKA protocol is more efficient. In addition, the security analysis shows that the proposed protocol is secure against both external attacks and internal ones. Finally, the proposed protocol is generated to MQKA protocol based on quantum search algorithm.

Comment on “Quantum key agreement protocol”

The first two-party Quantum Key Agreement (QKA) protocol, based on quantum teleportation, was proposed by Zhou et al. (Electron. Lett. 40(18) (2004) 1149). In this protocol, to obtain the key bit string, one of the parties uses a device to obtain the inner product of two quantum states, one being unknown, and the other one performs Bell measurement. However, in this paper, we show that it is not possible to obtain a device that would output the inner product of two qubits even when only one of the qubits is unknown. This is so because the existence of such a device would imply perfectly distinguishing among four different states in a two-dimensional vector space. This is not permissible in quantum mechanics. Furthermore, we argue that the existence of such a device would also imply a violation of the “No Signaling Theorem” as well.

Two-party quantum key agreement against collective noisy channel

Quantum key agreement (QKA) permits participants to constitute a shared key on a quantum channel, and no participants are able to independently determine the shared key. In fact, particles are frequently affected by channel noise in the transmission process of quantum channel. Under the cover of noise, attackers can launch malicious attacks. In this thesis, on account of the usage of entanglement swapping of GHZ state and logical Bell states, we design two two-party QKA protocols which are immune to collective-dephasing noise and collective-rotation noise, respectively. In comparison with the existing QKA protocols of two parties, the proposed protocols have better quantum resource cost and the qubit efficiency in the global scope. Security analysis reveals that they can resist not only attacks by participants but also external attacks.

New quantum key agreement protocol with five-qubit Brown states

We propose a new two-party quantum key agreement (QKA) protocol using five-qubit Brown states. One-way quantum transmission can be realized by merging Brown states and decoy photons randomly. The security of this protocol is shown to resist the outsider attack and participant attack over the ideal channel. Some methods are also proposed to ensure its security in noisy and lossy quantum channel. Finally, we generalize it and propose a multi-party QKA protocol based on Brown states.

New quantum key agreement protocols based on Bell states

We present a new two-party quantum key agreement (QKA) protocol based on Bell states. The participant transmits Bell states directly by inserting decoy photons in them randomly. The protocol is secure against the outsider attack and participant attack. Finally, it is generalized to multi-party QKA based on Bell states.

Quantum key agreement with Bell states and Cluster states under collective noise channels

The collective noises, which include the collective-dephasing noise and the collective-rotation noise, are the topical noises in quantum key agreement (QKA). How to eliminate the influence of the collective noises on quantum communication is a problem to be solved urgently. In this paper, based on logical quantum states, by using controlled-Z, controlled-NOT and unitary operations, two QKA protocols which can be immune to the collective-dephasing noise and the collective-rotation noise are proposed, respectively. The security analysis indicates that these two protocols can resist participant attack and outsider attacks which include Trojan-horse attacks, intercept-resend attack, measure-resend attack and entangle-measure attack. By comparing with the proposed two-party QKA protocols against the collective noises, it is clear that our protocols are more efficient.

New quantum key agreement protocols based on cluster states

A new two-party quantum key agreement (QKA) protocol is proposed based on four-qubit cluster states. Encoded four-qubit cluster states can be transmitted directly by means of order rearrangement operation. In contrast to existing QKA protocols based on four-qubit cluster states, it is unnecessary to perform two-way quantum communication. We analyze the security of this protocol and prove that it is secure in ideal conditions. We also propose the method to ensure the security of this protocol in noisy channel. Finally, we analyze the expansibility of the proposed QKA protocol and propose a three-party QKA protocol based on four-qubit cluster states.

Two-party quantum key agreement over a collective noisy channel

Quantum key agreement (QKA) allows participants to establish a shared key over a quantum channel, and no one of the participants can determine the shared key alone. Actually, particles are usually affected by noise during transmission in the quantum channel, and an aggressor can launch a baleful attack under the cover of noise. In this paper, based on logical Bell states, we propose two robust two-party QKA protocols immune to collective-dephasing noise and collective-rotation noise, respectively. The measurement correlation of quantum entanglement is utilized to establish a shared key. The proposed protocols are globally better in terms of quantum resource cost and qubit efficiency than existing two-party QKA protocols against collective noise. The security analysis demonstrates that they can resist common insider and outsider attacks.

Two-party quantum key agreement protocols under collective noise channel

Recently, quantum communication has become a very popular research field. The quantum key agreement (QKA) plays an important role in the field of quantum communication, based on its unconditional security in terms of theory. Among all kinds of QKA protocols, QKA protocols resisting collective noise are widely being studied. In this paper, we propose improved two-party QKA protocols resisting collective noise and present a feasible plan for information reconciliation. Our protocols’ qubit efficiency has achieved 26.67%, which is the best among all the two-party QKA protocols against collective noise, thus showing that our protocol can improve the transmission efficiency of quantum key agreement.

Two-party quantum key agreement with five-particle entangled states

A two-party quantum key agreement protocol is proposed with five-particle entangled states and the delayed measurement technique. According to the measurement correlation property of five-particle entangled states, two participants can deduce the measurement results of each other’s initial quantum states. As a result, two parties can extract the secret keys of each other by using the publicly announced value or by performing the delayed measurement, respectively. Thus, a shared key is fairly established. Since each particle is transmitted only once in quantum channel, the protocol is congenitally free from the Trojan horse attacks. It is shown that the protocol not only is secure against both participant and outsider attacks but also has no information leakage problem. Moreover, it has high qubit efficiency.

Two-party quantum key agreement protocol with four-particle entangled states

Based on four-particle entangled states and the delayed measurement technique, a two-party quantum key agreement protocol is proposed in this paper. In the protocol, two participants can deduce the measurement results of each other’s initial quantum states in terms of the measurement correlation property of four-particle entangled states. According to the corresponding initial quantum states deduced by themselves, two parties can extract the secret keys of each other by using the publicly announced value or by performing the delayed measurement, respectively. This guarantees the fair establishment of a shared key. Since each particle in quantum channel is transmitted only once, the protocol is congenitally free from the Trojan horse attacks. The security analysis shows that the protocol not only can resist against both participant and outsider attacks but also has no information leakage problem. Moreover, it has high qubit efficiency.

Two-party quantum key agreement against collective noise

In this paper, two two-party quantum key agreement protocols are proposed with logical $$\chi $$ź-states and logical Bell states. These two protocols can be immune to the collective-dephasing noise and the collective-rotation noise, respectively. They make full use of the measurement correlation property of multi-particle entangled states and the delayed measurement technique. This ensures that two participants can exchange the secret keys of each other and fairly establishes a shared key. There is no information leakage problem when establishing a shared key. The use of the delayed measurement technique and the decoy state technology makes the two protocols resist against both participant and outsider attacks. Furthermore, the two protocols are congenitally free from the Trojan horse attacks and have high qubit efficiency.

Two-party quantum key agreement based on four-particle GHZ states

Based on four-particle GHZ states, the double CNOT operation and the delayed measurement technique, a two-party quantum key agreement (QKA) protocols is proposed. The double CNOT operation makes each four-particle GHZ state collapse into two independent quantum states without any entanglement. Furthermore, one party can directly know the two quantum states and the other party can be aware of the two quantum states by using the corresponding measurement. According to the initial states of the two quantum states, two parties can extract the secret keys of each other by using the publicly announced value or by performing the delayed measurement, respectively. Then the protocol achieves the fair establishment of a shared key. The security analysis shows that the new protocol can resist against participant attacks, the Trojan horse attacks and other outsider attacks. Furthermore, the new protocol also has no information leakage problem and has high qubit efficiency.

Efficient multi-party quantum key agreement by cluster states

A quantum key agreement (QKA) protocol by utilizing a four-photon cluster state is proposed in this paper. The proposed QKA protocol extends the two-party QKA protocol with four-qubit cluster state (Shen et al. in Quantum Inf Process 13:2313---2324, 2014) into a multi-party case. The block transmission technique and decoy photons method are used in the presented protocol. Meanwhile, the qubit efficiency of the presented protocol is also improved by using the dense coding method. Security analysis shows that the proposed protocol is secure against both participant and outside attacks.

Two-party quantum key agreement with four-qubit cluster states

Based on four-qubit cluster states, we present a two-party quantum key agreement (QKA) scheme using unitary operations. In this scheme, two participants perform the unitary operation on the different photon of the same cluster state, which guarantees that each party contributes equally to the agreement key. By measuring each cluster state and decoding, these two participants can generate a four-bit classical key without the exchange of classical bits between them. Compared with other existed two-party QKA protocols, our scheme is efficient. Security analysis shows that our protocol is secure against both participant and outsider attack.

Protocols of quantum key agreement solely using Bell states and Bell measurement

Two protocols of quantum key agreement (QKA) that solely use Bell state and Bell measurement are proposed. The first protocol of QKA proposed here is designed for two-party QKA, whereas the second protocol is designed for multi-party QKA. The proposed protocols are also generalized to implement QKA using a set of multi-partite entangled states (e.g., 4-qubit cluster state and $$\Omega $$ state). Security of these protocols arises from the monogamy of entanglement. This is in contrast to the existing protocols of QKA where security arises from the use of non-orthogonal state (non-commutativity principle). Further, it is shown that all the quantum systems that are useful for implementation of quantum dialogue and most of the protocols of secure direct quantum communication can be modified to implement protocols of QKA.