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In this paper, we proposed an efficient single-state three-party quantum key agreement (QKA) protocol. We proved that the protocol can resist potential outside attacks and inside attacks, and we generalized the efficient single-state three-party QKA scheme into the case of the N-party by substituting N-particle entangled state for three-particle entangled state as the resource quantum states. Compared with the previous QKA protocols, our scheme contains the good features of previous schemes, i.e., using one kind of maximally entangled states as the quantum resource, no requirements for pre-shared key between different participants, and no requirements for executing any unitary operations or quantum entanglement swapping. Furthermore, our scheme has significant improvements in terms of the times of quantum states transmission, the consumed qubits, and the qubit efficiency. In particular, as the number of participants increases, the number of qubits required by our scheme increases linearly rather than exponentially. [ABSTRACT FROM AUTHOR]

Secure quantum multiparty computation is an important field of quantum computing. Many of the preceding aggregation approaches are (n, n) threshold-dependent strategies, where n denotes the total number of participants. The previous aggregating techniques cannot aggregate the secret effectively if one participant is dishonest. This paper presents a quantum technique for secure aggregation. This technique is (t, n) threshold-dependent scheme, where t is the threshold number of participants. We used the properties of quantum mechanics to provide security in quantum aggregation. This technique can compute the aggregation of secrets securely with less computation and communication costs. The proposed aggregation technique is efficient and secure as compared to existing techniques. The simulation results of the proposed technique ensure correctness and practicality. [ABSTRACT FROM AUTHOR]

This paper promotes reinforcement machine learning for route-finding tasks in quantum communication networks, where, due to the non-additivity of quantum errors, classical graph path or tree-finding algorithms cannot be used. We propose using a proximal policy optimization algorithm capable of finding routes in teleportation-based quantum networks. This algorithm is benchmarked against the Monte Carlo search. The topology of our network resembles the proposed 6 G topology and analyzed that quantum errors correspond to typical errors in realistic quantum channels. [ABSTRACT FROM AUTHOR]

The quantum permutation pad (QPP) is a cryptographic primitive, functionally similar to the one-time pad (OTP). Unlike OTP, QPP promises to remain secure even when the encryption key is used multiple times (Kuang and Barbeau in Quantum Inf Process 21(6):211, 2022. https://doi.org/10.1007/s11128-022-03557-y). QPP has emerged as a relatively recent proposal, with many aspects of its functionality yet to be explored. One such aspect is ensuring the security of this primitive against chosen-plaintext attacks. This study reveals that an eavesdropper can gain access to the encryption key under such an attack paradigm. Additionally, the security of a proposed practical encryption device built around PRNG and QPP primitives is examined (Kuang and Perepechaenko in EPJ Quantum Technol 9(1):26, 2022. https://doi.org/10.1140/epjqt/s40507-022-00145-y). We have found that simplified versions, in which the attacker has access to the input data of the QPP block, are vulnerable. It is crucial to note, however, that the described attack does not undermine the security of a complete implementation, as it requires a combined attack on both the PRNG and QPP. [ABSTRACT FROM AUTHOR]

Quantum secret sharing plays a crucial role in quantum cryptography. In this paper, we present a rational hierarchical (t,n)-threshold quantum secret sharing scheme based on Lagrange interpolation. In our scheme, participants possess rational and hierarchical properties, and the secret can be reconstructed when the number of rational participants satisfies the hierarchical (t,n)-threshold structure proposed in this paper. The reconstructed secret can encompass both classical information and quantum state information, enhancing the practicality and flexibility of our scheme compared to existing ones. Additionally, we redefine the utility of participants based on their roles in the secret recovery process. This newly defined utility allows for a more precise analysis of the correctness, fairness, and equilibrium of our scheme. Finally, our scheme not only resists a typical set of external attacks but also incorporates mechanisms to detect forgery and collusion among participants. [ABSTRACT FROM AUTHOR]

Proposed by Hillery et al., Quantum Secret Sharing (QSS) is a technique used to break a quantum secret into multiple pieces (called Shares), such that any proper subset of the pieces does not reveal any information about the original secret. The secret can be reconstructed only when all of the pieces are combined together. However, most of the QSS protocols assume that the shares are untampered, hence fail to regenerate the original secret if some of the shares are damaged due to several reasons like cheating participants, eavesdropping, etc. In order to tackle this practical challenge, Resilient Quantum Secret Sharing (RQSS) protocols are required. In this paper, we propose an RQSS protocol that uses Quantum Error Correcting Codes (QECC) for share generation and secret reconstruction. Our protocol generates n shares of a m-qubit quantum secret, owned by the dealer, and distributes it among nparticipants; moreover, it can regenerate the original secret even if k < n shares are damaged. To the best of our knowledge, no such generalized protocol exists in the available literature. [ABSTRACT FROM AUTHOR]

Quantum secret sharing is widely applied in the fields, such as communications and data transmission. In this paper, we propose an authenticable dynamic quantum multi-secret sharing scheme based on the Chinese remainder theorem. In our scheme, the dynamic update of the participants set is permissible without changing the shared secret. To share multi-secret, the distributor generates corresponding shares based on the Chinese remainder theorem and monotone span program, and the GHZ state acts as the information carrier traveling among the participants in the authorization set; the participants utilize the Hadamard operator and Pauli operators to embed their shares in the traveling particles. In this way, the participants will reconstruct multiple secrets. Furthermore, the proposed quantum digital signature algorithm based on entanglement swapping is utilized to realize the identity authentication between participants. The security analysis shows that the proposed scheme can resist intercept-resend attack, entanglement-measurement attack, internal dishonest participant attack, add or withdraw participant attack, and denial attack. [ABSTRACT FROM AUTHOR]

In the field of post-quantum security, isogeny-based cryptography stands out for its ability to fight quantum attacks. One of the key operations in isogeny-based schemes is finite field multiplication, which plays a crucial role in cryptographic protocols such as key exchange and digital signatures. To ensure practical implementations of these schemes, efficient finite field multiplication is essential. In this research, a novel optimization approach, the Crossover-Boosted Water Cycle Algorithm (CB-WCA), to enhance the efficiency of finite field multiplication in isogeny-based cryptography is proposed. By using both the WCA and a crossover method inspired by genetic algorithms, the CB-WCA effectively explores solution areas, aiming for the best solutions. The formulation of the finite field multiplication optimization problem and an objective function that quantifies the efficiency of the multiplication process based on computational cost is presented and defined. The CB-WCA is then applied to find the optimal set of parameters for finite field multiplication algorithms. Extensive experimental evaluations are conducted, comparing the performance of the CB-WCA-optimized algorithms with traditional optimization methods and other metaheuristic algorithms. Through the findings, it is evident that the CB-WCA stands out for its ability to achieve faster execution times and decrease computational costs. Furthermore, the optimized finite field multiplication algorithms are integrated into isogeny-based cryptographic schemes and evaluate their impact on cryptographic protocol efficiency and security. Real-world implementations showcase the practical applicability of the optimized algorithms in hardware and software environments. To ensure the security of the optimized algorithms, rigorous cryptanalysis is performed to verify their resilience against potential attacks, ensuring they meet the highest standards of security. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel scheme with a semi-honest third party (TP) to compute the intersection of two parties' sets privately. In our scheme, two groups of particles are firstly prepared by TP and then transmitted circularly among TP and two participants who need the intersection of their private sets. The two participants then perform the unitary operations on their received particles according to an initial encoding rule for their private sets, respectively, to help TP to obtain the result. We analyse the security of our scheme and show that it can resist both outside and inside attacks over ideal and noisy quantum channels. In addition, our scheme is feasible with current quantum technologies as it only requires simple quantum resources and operations. [ABSTRACT FROM AUTHOR]

In many communication scenarios, it is necessary to involve a third party for control and supervision. In the context of controlled bidirectional quantum secure direct communication (CBQSDC) protocols, the transmission of secret messages between two legitimate users is only permitted with the explicit permission of a controller. To address the issue of controlled communication, a CBQSDC protocol (CLYH2015) utilizing Bell states was proposed in the paper (Quant Inf Process 14, 3515–3522, 2015). Bell states have been widely recognized for their significance in the field of quantum secure direct communication. In a subsequent study published in (Quant Inf Process 16, 147, 2017), the research examined whether CLYH2015 protocol strictly requires the initial states to be Bell states. The conclusion drawn from this investigation is that CLYH2015 protocol working properly necessitates the use of Bell states as initial states. To explore alternative possibilities for the initial states in CLYH2015 protocol, a class of CBQSDC protocols employing the generalized Bell states (GBell states), a | 00 ⟩ + b | 11 ⟩ , b ¯ | 00 ⟩ - a ¯ | 11 ⟩ , a | 01 ⟩ + b | 10 ⟩ , and b ¯ | 01 ⟩ - a ¯ | 10 ⟩ , are designed where a and b are complex numbers with | a | = | b | = 1 2 , a ¯ and b ¯ the conjugate complex numbers of a and b, respectively. The class of designed CBQSDC protocols demonstrates several favorable properties, including resistance against information leakage, intercept-and-resend attacks, measure-resend attacks, as well as robustness against collective attacks. In addition, the unconditional security of the class of designed protocols is proved. Finally, to show the advantages of the class of designed protocols, they are compared with some with some previous closely associated protocols. Interestingly, it is worth noting that the Bell states can be considered a special case of the GBell states when both a and b are real numbers. Consequently, CLYH2015 protocol can be regarded as a particular instance of the designed CBQSDC protocols. This insight implies that the initial states in CLYH2015 protocol can be extended to include the GBell states, rather than being limited solely to the Bell states. [ABSTRACT FROM AUTHOR]

Quantum secure direct communication is an important branch of quantum cryptography. One of the main requirements of quantum secure direct communication is to ensure that no secret information can be stolen. Recently, a bidirectional quantum secure direct communication protocol [Quantum Information Processing 16, 147 (2017)] was proposed. It was believed that the intercept-and-resend attack and information leakage problem can be avoided via this protocol. However, in this paper, we point out that attackers can obtain useful information about the secret messages by constructing two intercept-and-resend attacks on the above protocol. Attackers can obtain Alice's secret message exclusive OR Bob's secret message by the first attack and both secret messages by the second attack. To resist the two constructed attacks, we design an improved bidirectional quantum secure direct communication protocol. Furthermore, we show that the designed protocol can resist the two constructed attacks and its efficiency has increased. It is interesting that the designed protocol can publish Alice's result states, i.e., Bob's initial states, without affecting its security. The designed protocol can prevent Alice (Bob) from obtaining Bob's (Alice's) secret message before Alice (Bob) sends her (his) secret message. This work can notice researchers to avoid similar security problems in constructing quantum cryptography protocols. [ABSTRACT FROM AUTHOR]

This work researches the implementation of the AES family with Pauli-X gates, CNOT gates and Toffoli gates as the underlying quantum logic gate set. First, the properties of quantum circuits are investigated, as well as the influence of Pauli-X gates, CNOT gates and Toffoli gates on the performance of the circuits constructed with those gates. Based on these properties and the observations on the hardware circuits built by Boyar et al. and Zou et al., it is possible to construct quantum circuits for AES's Substitution-box (S-box) and its inverse (S-box - 1 ) by rearranging the classical implementation to three parts. Since the second part is treated as a 4-bit S-box in this paper and can be dealt with by existing tools, a heuristic is proposed to search optimized quantum circuits for the first and the third parts. In addition, considering the number of parallelly executed S-boxes, the trade-offs between the qubit consumption and T · M values for the round function and key schedule of AES are studied. As a result, quantum circuits of AES-128, AES-192 and AES-256 can be constructed with 269, 333 and 397 qubits, respectively. If more qubits are allowed, quantum circuits that outperform state-of-the-art schemes in the metric of T · M value for the AES family can be reported, and it needs only 474, 538 and 602 qubits for AES-128, AES-192 and AES-256, respectively. [ABSTRACT FROM AUTHOR]

Quantum secret sharing is one of the important techniques in quantum cryptography. In this paper, we propose a novel dynamic hierarchical quantum secret sharing scheme with general access structure. Participants from different levels share the same secret. Firstly, a special hierarchical structure based on the generalized GHZ state is constructed, which expands the application value of the existing hierarchical quantum secret sharing. Secondly, this paper uses the monotone span program (MSP) and the generalized Pauli operator to realize the dynamic property of the scheme, which includes three aspects: The hierarchical access structure is variable; participants can join or leave, and the shared secret can be updated. Moreover, the shares of the participants can be protected so as to reduce communication consumption due to reuse of the shares. Finally, compared with other hierarchical quantum secret sharing schemes, the proposed scheme is not only more flexible but also more secure. [ABSTRACT FROM AUTHOR]

Quantum one-way function provides security for cryptographic protocols in quantum cryptography. Full quantum one-way function is a type of quantum one-way function that maps between quantum states and deals with pure quantum information. It was initially proposed by means of concatenating 'quantum–classical' and 'classical–quantum' quantum one-way functions. The first full quantum one-way function can be applied to quantum authentication, which uses quantum states to authenticate quantum states directly. However, the concatenation format restricts the implementation and cryptographic applications of this function. Considering the advantage of quantum circuit optimization in implementing quantum circuits to physical quantum devices, we propose a dynamic full quantum one-way function based on quantum circuit mapping. Quantum circuit optimization intrinsically generates the remapped quantum circuit which maps between quantum states but does not destroy them. The dynamic process of quantum circuit mapping contributes to the one-wayness of the dynamic full quantum one-way function. The experimental results show that this function is more realizable than the concatenated full quantum one-way function. The dynamic full quantum one-way function can be employed to construct a full quantum trapdoor one-way function which is 'easy to compute and invert' based on a trapdoor. Meanwhile, this new full quantum one-way function is proved to be very useful in quantum cryptography, especially in quantum currency notes. Our work promotes the development from full quantum one-way functions to future quantum cryptographic applications. [ABSTRACT FROM AUTHOR]

Multiparty quantum private comparison (MQPC) protocol enables the comparison of the private information of n parties through the combination of quantum mechanics with classical private comparison. In order to improve efficiency and practicality, this paper proposes an efficient MQPC protocol based on single photons and rotation encryption with the assistance of a semi-honest third party (TP). TP participates in preparing the initial single photon sequence, which is encrypted and sent to the participants one by one. The private inputs of participants are encoded into particular rotation angles that are used to convert the received single photon sequence to an unknown quantum state sequence, which is returned to TP in a closed-loop transfer mode. By implementing rotation encryption and multiplexing of single photons, the qubit efficiency and practicality of the protocol can be significantly improved, without the need for complex quantum technologies, such as entanglement swapping of high-dimensional quantum states, maximal entanglement states with n-particle and entanglement correlation between various particles in a quantum state. Moreover, the proposed protocol is simulated on IBM Quantum Experience to show its feasibility. Security analysis demonstrates that the proposed protocol is resistant to different types of attacks. [ABSTRACT FROM AUTHOR]

Quantum information stored in a qubit is rapidly lost to the environment. The realization of robust qubits is one of the most important challenges in quantum computing. Herein, we propose to embed a logical qubit within the manifold of a qudit as a scheme to preserve quantum information over extended periods of time. Under identical conditions (e.g., decoherence channels), the submanifold of the logical qubit exhibits extended lifetimes compared to a pure two-level system (qubit). The retention of quantum information further improves with separation between the sublevels of the logical qubit. Lifetime enhancement can be understood in terms of entropy production of the encoding and nonencoding subspaces during evolution under a quantum map for a d-level system. The additional pathways for coherent evolution through intermediate sublevels within a d-level manifold provide an information-preserving mechanism: reversible alternative channels to the irreversible loss of information to the environment characteristic of open quantum systems. [ABSTRACT FROM AUTHOR]

In this paper, we prove the unconditional security of a single-state circular mediated semi-quantum key distribution protocol. It starts with a third-party quantum server, TP, sending a string of qubits sequentially through two classical users Alice and Bob, and finally back to TP. We derive an expression for the key rate in the asymptotic scenario. When the communication parties Alice and Bob observe that the error rate is less than a determined threshold, the key rate is always greater than 0, so they can distill a string of secure secret keys. At the end of this paper, we extend this protocol to the multiple users case, where more than two classical users establish a string of security keys. [ABSTRACT FROM AUTHOR]

This paper proposes a new private comparison protocol based on four-dimensional three-particle GHZ-like states. The QPC protocol allows two participants with limited quantum abilities to compare their private information whether they are equal or not with the help of a semi-honest third party. The semi-honest third party means that it may be unfaithful on his own behavior, though it will execute the protocol loyally. The presented QPC protocol not only reduces the requirement on quantum operations without involving the unitary operation, but it also requires only the single-particle measurement. The quantum circuit of the six-qubit state and the measurement results are presented under the IBM Quantum Experimental platform. The correctness and the effectiveness of the suggested protocol are illustrated with some examples. In addition, detailed security analysis demonstrates that the proposed two-party QPC protocol is secure against the internal and external attacks. [ABSTRACT FROM AUTHOR]

In this work, the nonlocal quantum orthogonal product state (OPB) is first used to design a multi-party private comparison protocol, where multiple participants could securely compare the size of their private inputs. The ring topology is adopted for participants communicating with each other, which can significantly reduce the amount of information that the third party needs to process. But compared with the star topology, the ring topology is more vulnerable to the threat of participant attacks. Using the nonlocal OPB as the transmitted states can deal with this problem well, which prevents dishonest participants from obtaining valuable information related to the transmitted state. Vector coding, decoy particles, and random numbers are also used to promise the security of the protocol. In addition, this work requires less quantum capability. Compared with entangled states, nonlocal OPB is easier to prepare, and the operations that the participants need to perform are simple. The pre-shared key is not required, which consumes fewer quantum resources. [ABSTRACT FROM AUTHOR]

Continuous variable quantum cryptography has developed rapidly in recent decades, but how to verify identity in the continuous variable quantum system is still an urgent issue. To solve this problem, we propose a continuous variable quantum identification (CV-QI) protocol based on the correlation of the two-mode squeezed vacuum state and the continuous variable teleportation. The bidirectional identity verification between two participants of the communication can be achieved by the proposed CV-QI protocol. To guarantee the security, we make full use of the decoy state sequences during the whole process of the proposed CV-QI protocol. Besides, we provide the security analyses of the proposed CV-QI protocol, and analyses indicate that the security of the proposed CV-QI protocol is guaranteed. [ABSTRACT FROM AUTHOR]

Information security and identity authentication are both critical in communication. Authentication allows the receiver to receive (quantum) information and confirm the sender's identity. In 2019, Zheng and Long designed an improved version of Zhong et al. controlled quantum secure direct communication with authentication (CQSDCA) protocol, which uses the five-particle cluster state and an exclusive-or (XOR) operation. This protocol ensures data transfer security by including authentication and control phases. However, it was found in this study that the improved CQSDCA protocol has two weaknesses: (1) an external attacker may impersonate the sender, and (2) an external attacker could modify the messages sent by the sender. To solve these problems, we designed a protocol that uses part of a pre-shared key to determine particle sequence ordering and utilizes the computation of hash functions for identity authentication. These improvements prevent modification and impersonation attacks by an external attacker, thus improving the security of the CQSDCA protocol. [ABSTRACT FROM AUTHOR]

This paper proposes a cheating identifiable (t, m) threshold quantum secret sharing scheme based on the d-dimensional Bell state and single-qudit unitary operations. In the proposed protocol, the dealer generates a Bell state and transmits the first particle to the participants; then, t out of m participants perform the unitary operations on the Bell states' particle. The dealer shares both classical and quantum information. The Bell states are used to reconstruct the secret and identify the malicious behavior of a dishonest participant. After verifying any eavesdropping and dishonest participant, the dealer transforms a unitary operation on the second particle of the Bell state and sends it to the participant to regenerate the secret. The protocol is reliable in identifying dishonest participants and negating any eavesdropping. The proposed protocol is more adaptable, effective, and practical than the relevant quantum secret sharing schemes. [ABSTRACT FROM AUTHOR]

We investigate the security assumptions behind three public-key quantum money schemes. Aaronson and Christiano proposed a scheme based on hidden subspaces of the vector space F 2 n in 2012. It was conjectured by Pena et al. (IACR international workshop on public-key cryptography, pp 194–213. Springer, 2015) that the hard problem underlying the scheme can be solved in quasi-polynomial time. We confirm this conjecture, and hence prove that the scheme is insecure, by giving a polynomial time quantum algorithm for the underlying problem. Our algorithm is based on computing the Zariski tangent space of a random point in the hidden subspace. Zhandry (Quantum lightning never strikes the same state twice 11, 2017. ) proposed a scheme based on multivariate hash functions. We prove that Zhandry’s scheme is insecure by giving a polynomial time quantum algorithm for cloning a money state with high probability. Our algorithm uses the verification circuit of the scheme to produce a banknote from a given serial number. Kane et al. (Quantum money from quaternion algebras, 2021. ) proposed a scheme based on quaternion algebras. The underlying hard problem in their scheme is cloning a quantum state that represents an eigenvector of a set of Hecke operators. We give a polynomial time quantum reduction from this hard problem to a linear algebra problem. Although our reduction does not break this scheme, the latter problem is much easier to understand, and we hope that our reduction opens new avenues to future cryptanalyses of the scheme. [ABSTRACT FROM AUTHOR]

Mediated semi-quantum key distribution (M-SQKD) allows two "semi-quantum" or "classical" users to establish a secret key with the help of a third party (TP), in which TP has full quantum power and possibly adversarial. It is the basis of the multi-party semi-quantum cryptography protocol for securing the private data of classical users. In this work, we propose a M-SQKD protocol based on circular transport structure and prove the protocol is unconditional security. Even in the worst case (i.e., TP is untrusted), the protocol's noise tolerance is also close to the BB84 protocol. The results show that our protocol can reach the similar level of security as the full quantum protocol. Besides, due to the scalability of the circular transport structure, our protocol is easily extended to multi-party scenarios, which offers an approach to realizing multiple "classical" users' key distribution. Therefore, it can be used to protect the private data of multiple classical users and may have potential application scenarios in the future. [ABSTRACT FROM AUTHOR]

Lately, Tian et al. proposed a novel semi-quantum private comparison (SQPC) protocol without pre-shared key, which reduces the complexity and cost of the protocol. However, we found there exist some security problems in Tian's SQPC protocol, such that participants' secret information can easily be leaked. In addition, based on Tian's SQPC protocol, we proposed an improved SQPC protocol that has a higher security level. [ABSTRACT FROM AUTHOR]

The quantum unclonable theorem solves the problem of uncounterfeitability in quantum money schemes, however, few of them consider imposing limits on the minting capacity of banks, and thus, they may generate more quantum money than users require or distribute the same currency multiple times for their own benefit. In this paper, a quantum money scheme with supervision is proposed. First, a third-party regulator is introduced to jointly mint and verify the quantum virtual money together with the minter (i.e., bank) and the minter can no longer carry out mintage and verification independently. Second, the regulator is set to be a purely classical party and the minter undertakes most of quantum computing work, which makes it possible for regulator to mint and verify the quantum money through classical channel. Last, the security analysis shows that the proposed quantum money scheme is secure against any polynomial time attackers. [ABSTRACT FROM AUTHOR]

We Haar uniformly generate random states of various ranks and study their performance in an entanglement-based quantum key distribution (QKD) task. In particular, we analyze the efficacy of random two-qubit states in realizing device-independent (DI) QKD. We first find the normalized distribution of entanglement and Bell-nonlocality which are the key resource for DI-QKD for random states ranging from rank-1 to rank-4. The number of entangled as well as Bell-nonlocal states decreases as rank increases. We observe that the decrease in the secure key rate is more pronounced in comparison with that of the quantum resource with the increase in rank. We find that the pure state and Werner state provide the upper and lower bound, respectively, on the minimum secure key rate of all mixed two-qubit states possessing the same magnitude of entanglement under general as well as optimal collective attack strategies. [ABSTRACT FROM AUTHOR]

1-out-of-n oblivious transfer is an important research topic in secure multiparty computation, including its quantum version, i.e., quantum oblivious transfer (QOT). However, most QOT protocols (including its most practical variant called QKD-based quantum private query) cannot efficiently send the receiver exact one bit from the n bits transmitted by the sender. These protocols' communication complexity is usually O(nlogn). Since modern data size can be extremely large, it is important to reduce this communication as much as possible. In this sense, we propose a more efficient 1-out-of-n QOT protocol, whose communication complexity is O(logn). A potential loophole in our protocol is part of transmitted bits may be partial correlated. We then give an improved protocol to eliminate their correlation with communication complexity of O(n). Besides, our protocol has better performance in resisting the joint-measurement attack. [ABSTRACT FROM AUTHOR]

Duality in the entanglement of identical particles manifests that entanglement in only one variable can be revealed at a time. We demonstrate this using polarization and orbital angular momentum (OAM) variables of indistinguishable photons generated from parametric down-conversion. We show polarization entanglement by sorting photons in even and odd OAM basis, while sorting them in two orthogonal polarization modes reveals the OAM entanglement. Indistinguishable photons entangled in two variables could find applications in robust quantum communication, remote entanglement generation and distributed quantum sensing. [ABSTRACT FROM AUTHOR]

Since the seminal work of Chen et al. to construct pseudorandom functions (PRFs) from the public random permutations, a series of designs of beyond-birthday-bound secure PRFs or message authentication codes(MACs) have been proposed, like pEDM , pPMAC _ Plus , PDM * MAC , and 1 K - PDM * MAC , etc. These constructions were classically proved to be secure at least up to O (2 2 n / 3) queries. In this paper, we consider to attack these constructions in the quantum setting. In particular, we show the key-recovery attack against pEDM and pPMAC _ Plus with O (n · 2 n / 2) quantum queries by using Grover-meets-Simon algorithm. Moreover, a forgery attack is given against the constructions PDM * MAC and nEHtM p with O(n) quantum complexity, and under the same query complexity, we can even recover the key of 1 K - PDM * MAC . [ABSTRACT FROM AUTHOR]

Quantum cryptography is the fastest growing field in quantum information science. In this paper, we demonstrate the application of quantum cryptography to financial security. Using the entanglement properties of χ -state particles and the distributed quantum one-time pad algorithm, we propose a new quantum blind signature scheme combined with the scenario requirements of supply chain finance. The main idea of the scheme is that each participant obtains a key with an associated relationship by measuring χ -state particles, and the participants sign and verify the information according to the distributed quantum one-time pad algorithm and the above key obtained. We carefully proved the correctness of the scheme. Under the security analysis, we preset five common attack methods using the scenario-resistance method. We verify that our scheme can prevent them. [ABSTRACT FROM AUTHOR]

Initially, we address two issues that exist in multiparty quantum private comparison protocols. One among those arises when XOR operation is used in the multiparty comparison. The other issue occurs due to the poor implementation of multiparty computation, which leads to semi-honest third-party to access private data of the participants. Then, we propose a multiparty quantum private comparison protocol based on quantum walks on a circle. The protocol checks whether all parties (participants) hold the same value or not with the help of a semi-honest third-party (TP). Finally, we prove the correctness and security of the proposed system. [ABSTRACT FROM AUTHOR]

As one of the primitive operations of quantum cryptography, quantum secure multiparty multiplication plays an important role in practical applications. In this paper, we propose a (k, n)-threshold dynamic quantum secure multiparty multiplication protocol. (i) Based on Shamir's threshold scheme, the threshold (k, n) can be implemented; (ii) In the multiparty multiplication phase, the cheating behavior of participants can be detected by the one-to-one correspondence of hash values; (iii) Any m participants can dynamically join or exit during the execution of the protocol. Moreover, the method of this paper can also achieve dynamic quantum secure multiparty summation. Further, the security analysis shows that our protocol is resistant to intercept-resend attack, entangle-measure attack, Trojan horse attack, and participant attack. [ABSTRACT FROM AUTHOR]

Secure communication has achieved a new dimension with the advent of the schemes of quantum key distribution (QKD) as in contrast with classical cryptography, quantum cryptography can provide unconditional security. However, a successful implementation of a scheme for QKD requires identity authentication as a prerequisite. A security loophole in the identity authentication scheme may lead to the vulnerability of the entire secure communication scheme. Consequently, identity authentication is extremely important, and in the last three decades several schemes for identity authentication using quantum resources have been proposed. The chronological development of these protocols, which are now referred to as quantum identity authentication (QIA) protocols, is briefly reviewed here with specific attention to the causal connection involved in their development. The existing protocols are classified on the basis of the required quantum resources, and their relative merits and demerits are analyzed. Further, in the process of the classification of the protocols for QIA, it is observed that the existing protocols can also be classified in a few groups based on the inherent computational tasks used to design the protocols. Realization of these symmetries has led to the possibility of designing a set of new protocols for quantum identity authentication, which are based on the existing schemes for the secure computational and communication tasks. The security of such protocols is also critically analyzed. [ABSTRACT FROM AUTHOR]

Malicious users using quantum computers can employ quantum attacks on modern cryptography algorithms. Grover's search algorithm, a well-known quantum algorithm, can reduce the search complexity of O (2 n) to 2 n for symmetric key cryptography with an n-bit key. To apply the Grover search algorithm, the target encryption process must be implemented in a quantum circuit. In this paper, we present optimized quantum circuits for Korean block ciphers based on ARX architectures. We adopt the optimal quantum adder and design it in parallel way. Compared to previous implementations, we provide performance improvements of 78%, 85%, and 70% in terms of circuit depth for LEA, HIGHT, and CHAM, respectively, while keeping the number of qubits and quantum gates minimum. The depth of a circuit is an important factor related to its execution time. Finally, we estimate the cost of the Grover key search for Korean block ciphers and evaluate the post-quantum security based on the criteria presented by NIST. [ABSTRACT FROM AUTHOR]

Quantum group signature (QGS) is an important variation in arbitrated quantum signature, and it can be used for special demands. However, most of existing QGS schemes suffer from different aspects of disavowals and forgeries owing to the employed encryption algorithm. We present a novel QGS scheme using single-key-controlled chained-CNOT and coin operator (SKC-CCCO), an encryption combined by key-controlled chained-CNOT and key-controlled coin operator. The former is sensitive to modifications of the message and the key due to its intrinsic chain effect, and the latter consists of random unitary operators instead of restricted Pauli operators in quantum one-time pad. It encrypts the ciphertext and the signer's identity information to generate the group signature. Moreover, the quantum-walk-based teleportation is applied to transmit the ciphertext replica from the signer to the verifier for facilitating signature validity verification, in which advance preparation of the required entangled states and tricky joint measurements get averted. Additionally, the utilization of random number along with public board evades the verifier's denials on the receipt and the integrality of the signature. Security and performance analyses show that the SKC-CCCO-based QGS scheme conforms to security requirements of a QGS and that the SKC-CCCO encryption possesses adequate keyspace and key sensitivity property against brute force attacks. Further, discussions exhibit the scheme has better efficiency in terms of transmission and key usage. [ABSTRACT FROM AUTHOR]

Semi-quantum key distribution (SQKD) protocols attempt to establish a shared secret key between users, secure against computationally unbounded adversaries. Unlike standard quantum key distribution protocols, SQKD protocols contain at least one user who is limited in their quantum abilities and is almost "classical" in nature. In this paper, we revisit a mediated semi-quantum key distribution protocol, introduced by Massa et al. (Experimental quantum cryptography with classical users, 2019. arXiv preprint arXiv:1908.01780), where users need only the ability to detect a qubit, or reflect a qubit; they do not need to perform any other basis measurement; nor do they need to prepare quantum signals. Users require the services of a quantum server which may be controlled by the adversary. In this paper, we show how this protocol may be extended to improve its efficiency and also its noise tolerance. We discuss an extension which allows more communication rounds to be directly usable; we analyze the key-rate of this extension in the asymptotic scenario for a particular class of attacks and compare with prior work. Finally, we evaluate the protocol's performance in a variety of lossy and noisy channels. [ABSTRACT FROM AUTHOR]

In this paper, a lightweight three-user secure quantum summation protocol is put forward by using single-particle states, which can accomplish the goal that three users cooperate together to calculate the modulo 2 addition of their private messages without the help of a third party. This protocol only requires single-particle states rather than quantum entangled states as the initial quantum resource and only needs single-particle measurements and Bell basis measurements. This protocol needs none of quantum entanglement swapping, the Pauli operations, the controlled-not (CNOT) operation, the Hadamard gate or a pre-shared private key sequence. Security analysis proves that this protocol is secure against both the outside attacks and the participant attacks. Compared with the existing two-dimensional three-user quantum summation protocols, this protocol more or less takes advantage over them on the aspects of the initial quantum resource, users' quantum measurement, the usage of quantum entanglement swapping, the usage of Pauli operations, the usage of CNOT operation or the usage of Hadamard gate. [ABSTRACT FROM AUTHOR]

The dihedral coset problem (DCP) that comes from the hidden subgroup problem over dihedral group is one of the fundamental problems in quantum computation, and its hardness has become a promising cryptographic assumption of post quantum cryptography. In this work, we carry out a quantum cryptographic scheme based on dihedral coset states, which is a novel quantum cryptography that not only exploits the principles of quantum physics but also depends on the post-quantum hardness of DCP N ℓ , where ℓ is the number of samples of DCP states and N is the modulus. Specifically, we propose a bipartite quantum key agreement protocol based on dihedral coset states, and by using it we demonstrate a quantum secure communication scenario that ⌊ ℓ / 4 ⌋ bits of information can be transmitted securely. Finally, we discuss the security analysis of our proposal under the optimal measurement attack and show that the proposal can achieve the maximum secrecy capacity with information-theoretic security under the constraint of m = Θ (log N - 4) for the large N, where m denotes the number of DCP states transmitted in the quantum channel. [ABSTRACT FROM AUTHOR]

In this study, we analyse the efficiency of a protocol with discrete modulation of continuous variable non-Gaussian states, that is, the coherent states having the addition of one photon followed by the subtraction of one photon (PASCS). We calculate lower bounds of the asymptotic key rates against Gaussian collective attacks based on the fact that for sufficiently small modulation variances we remain close to the protocol with Gaussian modulation. We compare the results of a four-state protocol (quadrature phase-shift-keying) using PASCS with the ones using coherent states, and show that under the same environmental conditions, the former always outperforms the latter, allowing to increase the maximum possible distance for secret key generation. Interestingly, we find that for the protocol using discrete-modulated PASCS, the noisier the line, the better will be its performance compared to the protocol using coherent states, showing that continuous variable non-Gaussian states can be considerably more advantageous for performing quantum key distribution in non-ideal situations. [ABSTRACT FROM AUTHOR]

A mutual authentication quantum key agreement protocol can authenticate participants' identities before establishing shared keys fairly. Therefore, it is more in line with the actual demand than the general quantum key agreement protocols. With Bell states and their entanglement exchange relations, a new mutual authentication quantum key agreement protocol is proposed. The participants can mutually authenticate each other's identity by using their secret identity information and the measurement correlation property of Bell states. Moreover, they can negotiate session keys fairly with the entanglement exchange relations of Bell states. The new mutual authentication quantum key agreement protocol is proved to be unconditionally secure and has good performance. [ABSTRACT FROM AUTHOR]

We propose a new cryptographic resource, secure modulo zero-sum randomness, as a resource to implement a task of secure modulo summation, and its quantum protocol. Secure modulo summation is the calculation of modulo summation Y 1 + ⋯ + Y m when m players have their individual variables Y 1 , ... , Y m with keeping the secrecy of the individual variables. Secure modulo zero-sum randomness is a set of m variables X 1 , ... , X m held by m players that satisfy the zero sum condition X 1 + ⋯ + X m = 0 with a certain security condition. This paper explains the relation between these two concepts and proposes a quantum verifiable protocol for secure modulo summation. The advantage for quantum protocol is the verifiability based on self-testing, which does not need to trust measurement devices and can be realized by using a statistical concept, significance level, while any classical method needs to trust several components of the protocol. Then, we propose various cryptographic applications for secure modulo zero-sum randomness. We also compare our quantum verifiable protocol with the conventional method for secure modulo summation. [ABSTRACT FROM AUTHOR]

Secure multiparty summation plays an important role in the field of secure communication. In this paper, we give a cryptanalysis of a generalized quantum protocol for secure multiparty summation and find a security leak, whereby a dishonest player can steal all the other players' shares and the summation of secrets without being found, which is in conflict with the security requirement for secure multiparty summation. Furthermore, we analyze the reason and present an improved version to deal with the security problem. [ABSTRACT FROM AUTHOR]

Quantum secure direct communication (QSDC) and deterministic secure quantum communication (DSQC) are two important branches of quantum cryptography, where one can transmit a secret message securely without encrypting it by a prior key. In the practical scenario, an adversary can apply detector-side-channel attacks to get some non-negligible amount of information about the secret message. Measurement device–independent (MDI) quantum protocols can remove this kind of detector-side-channel attacks, by introducing an untrusted third party, who performs all the measurements during the protocol with imperfect measurement devices. In this paper, we put forward the first MDI-QSDC protocol with user identity authentication, where both the sender and the receiver first check the authenticity of the other party and then exchange the secret message. Then, we extend this to an MDI quantum dialogue protocol, where both the parties can send their respective secret messages after verifying the identity of the other party. Along with this, we also report the first MDI-DSQC protocol with user identity authentication. Theoretical analyses prove the security of our proposed protocols against common attacks. [ABSTRACT FROM AUTHOR]

Quantum public-key cryptography (QPKC) can perform the management and distribution of keys in a large-scale quantum communication network, thus being the foundation for many cryptographic applications. The QPKC system, which uses qubit rotation as a quantum one-way function, is one of the most practical public key systems and has found many valuable extensions. In this paper, we analyze and provide supplementary properties of binary qubit rotation. On the basis of Nikolopoulos'work (Phys Rev A 77(3):032348, 2008), we have extended the qubit rotation to three dimensions and propose a ternary QPKC protocol. The protocol can resist forward search attack and achieve higher security than binary QPKC protocol. Theoretically, the protocol can be extended to a higher dimension. [ABSTRACT FROM AUTHOR]

The paper describes a quantum technique for relativistic high-dimensional key distribution without public announcement of bases, also known as quantum key expansion, which securely transfers 2 bits per setup usage given that a pre-shared bit is at disposal to the parties. This becomes possible by utilizing both phase and polarization encodings. The work presents both single-photon and weak-coherent-state interferometric setups for the purpose of the proposed scheme. The proposed key distribution is characterized with higher rate than any existing protocols of such type. Also, the proposed scheme has the highest efficiency of the existing quantum key expansion protocols. It should be noted that the highest efficiency is obtained only for the case of single-photon regime of the scheme; the weak-coherent-pulse regime manifests lower efficiency. Moreover, compared to other relativistic quantum key distribution schemes, the proposed one shows better rate and efficiency (weak-coherent-pulse regime is considered). The improvement comes at no security cost. However, at the cost of improving efficiency and rate, the practicality of the scheme reduces. [ABSTRACT FROM AUTHOR]

Key-alternating Feistel (KAF) cipher, refer to Feistel scheme with round functions of the form F(x ⊕ k), where k is the round-key and F is a public random function. This model roughly captures the structures of many famous Feistel ciphers, and the most prominent instance is DES. In order to analyze how KAF cipher can achieve security under simpler and more realistic assumptions from the view of provable security, a kind of KAF cipher is widely studied, which is called KAF cipher for shorter keys. Existing KAF ciphers for shorter keys (SCIS 2021, ASIACRYPT 2018 and ACNS 2020) have been proved to be super pseudorandom permutations (SPRPs) and can achieve birthday bound security. In this paper, we focus on the quantum security of the KAF ciphers for shorter keys. We show that the KAF ciphers for shorter keys are insecure against quantum chosen-plaintext attacks (qCPA). According to our study, the KAF ciphers for shorter keys can be distinguished from random permutation based on Simon's algorithm in polynomial time. We also show that the KAF ciphers for shorter keys with arbitrary rounds are insecure in the qCPA setting. In addition, we propose quantum multi-user distinguishing attacks on the KAF ciphers for shorter keys. The results show that the KAF ciphers for shorter keys can be distinguished from random permutation in polynomial time in the qCPA setting even if either the round function or the number of rounds is unknown. [ABSTRACT FROM AUTHOR]

In this paper, we define two specific secure multiparty summations and further present the corresponding measurement-device-independent quantum secure multiparty summation protocols, in which each party with a private input only performs simple single-particle operators, not any complex quantum measurements. The proposed protocols not only achieve the information-theoretical security, but also ensure the good feasibility and the high performance. [ABSTRACT FROM AUTHOR]

In this paper, we propose a two-party semiquantum summation protocol, where two classical users can accomplish the summation of their private binary sequences with the assistance of a quantum semi-honest third party (TP). The term 'semi-honest' implies that TP cannot conspire with others but is able to implement all kinds of attacks. This protocol employs logical qubits as traveling particles to overcome the negative influence of collective–dephasing noise and need not make any two parties pre-share a random secret key. The security analysis turns out that this protocol can effectively prevent the outside attacks from Eve and the participant attacks from TP. Moreover, TP has no knowledge about the summation results. [ABSTRACT FROM AUTHOR]

In today's scenario of computing paradigm, the cloud framework has become a significant solution on peak of virtualization for the utilization of computing models. However, the model has the latent to influence users and organizations; there are several security issues over shared data. In existing models for cloud data security, several considerations are made. Still, there is a requirement for ensuring cloud storage security with Third Party Auditing and distributed accountability. For that, this paper develops a new model called Enhanced Cloud Security Model using Quantum Key Distribution Protocol (ECSM-QKDP), for providing cloud storage security and manage with data dynamics, quantum key cryptography is incorporated. Moreover, this work considers the scenario of communication between three entities such as, Cloud Server, Data Owner and Legitimate User (LU), in which the quantum keys are shared in two steps. In the first step, BB84 QKDP is used and in the second process, Secure Authentication Protocol is framed based on distance bounding and secure keys, which are generated here using Hierarchical Attribute-Set based Encryption. By utilizing the model, the secured keys are transmitted through trusted channel to the LU. The results show that the proposed model provides effective results than existing models. [ABSTRACT FROM AUTHOR]