Private Comparison Research Articles

Multi-Party Quantum Private Comparison with Qudit Shifting Operation

In this paper, a multi-party quantum private comparison (MQPC) protocol is proposed based on the qudit shifting operation. The semi-honest third party (TP) prepares the initial particles and sends them to the first user. Then, each of n users encodes his private integers on the travelling particles with the qudit shifting operations and transmits them to the next user. Finally, the travelling particles are transmitted back to TP. The equality of the private integers from n users can be determined within one time execution of the protocol. It is verified that the proposed protocol is secure against both the outside attack and the participant attack. One user cannot obtain other users’ private integers except for the case that their private integers are same. TP cannot know the private integers from n users except their comparison result.

Quantum Private Comparison without Classical Computation

There are usually two kinds of signals i.e. quantum and classical to process in lots of existing protocols of quantum private comparison (QPC), for they employ quantum technology and classical computation to implement security and comparison, respectively. Classical operations and their information are prone to classical attacks with insufficient security. Therefore, a protocol of quantum gate-based QPC has been proposed without classical operations, but it is only applicable for qubits of computational basis. For its application to diagonal basis, this paper uses quantum gates and GHZ states to propose a new QPC protocol without classical data to process. There being no classical computation could lead to the improvement of security. The presented protocol is not only simple and efficient but also broadening applicable occasions. The analyses indicate its correctness and security.

Cryptanalysis and improvement of several quantum private comparison protocols

Recently, Wu et al (2019 Int. J. Theor. Phys. 58 1854) found a serious information leakage problem in Ye and Ji’s quantum private comparison protocol (2017 Int. J. Theor. Phys. 56 1517), that is, a malicious participant can steal another’s secret data without being detected through an active attack means. In this paper, we show that Wu et al’s active attack is also effective for several other existing protocols, including the ones proposed by Ji et al and Zha et al (2016 Commun. Theor. Phys. 65 711; 2018 Int. J. Theor. Phys. 57 3874). In addition, we propose what a passive attack means, which is different from Wu et al’s active attack in that the malicious participant can easily steal another’s secret data only by using his own secret data after finishing the protocol, instead of stealing the data by forging identities when executing the protocol. Furthermore, we find that several other existing quantum private comparison protocols also have such an information leakage problem. In response to the problem, we propose a simple solution, which is more efficient than the ones proposed by Wu et al, because it does not consume additional classical and quantum resources.

Improvement of multi-party quantum private comparison protocol using d-dimensional basis states without entanglement swapping

Recently, Gu et al. (2019, arXiv:1907.02656) and Zhang et al. (Quantum Inf Process (2019)18:336) independently pointed out that in Yang et al.’s quantum summation protocol (Quantum Inf Process (2018) 17:129), the party in charge of preparing the initial quantum states is able to steal other parties’ private integer strings without being discovered by launching two special kinds of attack. In this paper, it is pointed out that in Liu et al.’s MQPC protocol, if the third party (TP) named Calvin launches the similar attacks, she can also steal the private secrets from n parties without being discovered. Then, two methods are put forward to avoid this drawback, i.e., the first one is to add the process of checking whether the quantum states shared among n parties are genuinely in the state of |W〉12⋯n while the second one is to encrypt the private secrets from n parties with a private key sequence shared among them beforehand.

NIH funding trends to US medical schools from 2009 to 2018.

Total NIH funding dollars have increased from 2009–2018. We questioned whether this growth has occurred proportionately around the country and throughout allopathic medical schools. Therefore, we compared the trend in NIH grant funding from 2009 to 2018 for United States allopathic medical schools among historically top-funded schools, private and public schools, and by region of the country. Changes in both unadjusted and real funding dollars over time revealed a significant difference. Region was the only significant factor for mean percent change in funding from 2009–2018, with the Western region showing a 33.79% increase in purchasing power. The Northeastern region showed a -6.64% decrease in purchasing power while the Central and Southern regions reported changes of 2.46% and -6.08%, respectively. The mean percent increases were more proportional and nonsignificant in the public vs. private institutions comparison, at -3.41% and 4.75%, respectively. Likewise, the top-funded institutions vs. other institutions comparisons demonstrated modest, nonsignificant differences. However, although the relative changes might be proportional, the absolute increases evidence a pattern of growing cumulative advantage that favor the highest-funded institutions and private institutions. The potential consequences of this disproportionate increase include health science education, biomedical research, and patient access disparities in large parts of the country. The NIH and the scientific community should explore potential solutions in its funding models.

Continuous variable controlled quantum dialogue and secure multiparty quantum computation

A continuous variable (CV) controlled quantum dialogue (QD) scheme is proposed. The scheme is further modified to obtain two other protocols of (CV) secure multiparty computation. The first one of these protocols provides a solution of two-party socialist millionaire problem, while the second protocol provides a solution for a special type of multi-party socialist millionaire problem which can be viewed as a protocol for multiparty quantum private comparison. It is shown that the proposed scheme of (CV) controlled (QD) can be performed using bipartite entanglement and can be reduced to obtain several other two- and three-party cryptographic schemes in the limiting cases. The security of the proposed scheme and its advantage over corresponding discrete variable (DV) counterpart are also discussed. Specifically, the ignorance of an eavesdropper, i.e., information encoded by Alice/Bob, in the proposed scheme is shown to be more than that in the corresponding (DV) scheme, and thus the present scheme is less prone to information leakage inherent with the (DV) (QD) based schemes. It is further established that the proposed scheme can be viewed as a (CV) counterpart of quantum cryptographic switch which allows a supervisor to control the information transferred between the two legitimate parties to a continuously varying degree.

Semi-quantum private comparison based on Bell states

In this paper, we propose two semi-quantum private comparison (SQPC) protocols based on Bell states. With the help of a semi-honest quantum third party (TP), two classical users can compare the equality of their secrets without leaking them. That TP is semi-honest means she may misbehave on her own, but she is not allowed to conspire with any user. The quantum measurement is not invoked in the first protocol, whereas the classical user in previous SQPC protocols has to be equipped with quantum measurement equipment. In the second protocol, the classical user prepares the opposite states based on her (his) measurements. By this way, all cases can produce the sharing key. The two protocols are more efficient than the previous SQPC protocols. What is more, we show that our protocols are secure against some famous attacks, such as the intercept-resend attack, the measure-resend attack, the entangle-measure attack and the participant attack.

New Quantum Private Comparison Protocol Without a Third Party

New Quantum Private Comparison Protocol Without a Third Party

Quantum Private Comparison Protocol without a Third Party

This paper presents a novel quantum private comparision (QPC) protocol based on the single-qubit rotations, quantum SWAP-test and quantum SWAP gates. The proposed QPC protocol can secretly compare information of the two participants without the help of a third party (TP). The security analysis of the presented QPC protocol shows that it is quantum indistinguishable and information theory security for all outside attackers and inside attackers. Finally, we compare some important features of the presented QPC protocol with other QPC protocols. The results show that the proposed protocol has some advantages different from previous protocols.

Quantum Private Comparison Protocol Based on Four-Particle GHZ States

A new quantum private comparison protocol with four-particle GHZ states is proposed. Unlike most previous quantum private comparison protocols, this quantum private comparison protocol can compare the equality of three information bits in each comparison, which could greatly reduce the times of comparisons. The private input of either party will not be leaked out to others, including participants. Besides, it’s simple to implement the protocol with current technologies since only single-particle measurements and Bell measurements are involved. Furthermore, our protocol has good performance of withstanding various outside attacks and participant attacks.

An attempt at universal quantum secure multi-party computation with graph state

Quantum secure multi-party computation (SMC) is a vital field in quantum cryptography. In this paper, we try to resolve SMC problems universally via graph states. Firstly, three kinds of quantum SMC protocols are investigated, which are quantum private comparison protocol, quantum millionaire protocol and quantum multi-party summation protocol. Secondly, three proposed protocols are reviewed, and then the core of them is summarized. We further find that the computation, deduced as modulo subtraction, can be resolved by using graph state. This implies that our protocols are universal in part and will be widely applicable. Thirdly, analyses show that the proposed protocols are correct and secure. Our research will promote the development of quantum secure multi-party computation.

Quantum Gate-Based Quantum Private Comparison

Many existing protocols of quantum private comparison (QPC) are often made up of quantum part and classical part, because they employ quantum technology to provide security and use classical computation to perform the comparison. This could result in some lurking unfavourable effects such as insufficient security. To improve the QPC security, the paper presents a QPC protocol without the classical part, which uses Bell states as the quantum resource and substitutes the action of quantum gate for the classical computation. It needs no other complex quantum operations including quantum entanglement swapping technology. Except the phase of the eavesdropping check, quantum measurement isn’t required at one party either. The presented protocol is not only simple and efficient but also of better security. The analyses indicate its correctness so it could serve as an alternative way to implement QPC.

Secure dynamic multiparty quantum private comparison

We propose a feasible and efficient dynamic multiparty quantum private comparison protocol that is fully secure against participant attacks. In the proposed scheme, two almost-dishonest third parties generate two random keys and send them to all participants. Every participant independently encrypts their private information with the encryption keys and sends it to the third parties. The third parties can analyze the equality of all or some participants’ secrets without gaining access to the secret information. New participants can dynamically join the protocol without the need for any additional conditions in the protocol. We provide detailed correctness and security analysis of the proposed protocol. Our security analysis of the proposed protocol against both inside and outside attacks proves that attackers cannot extract any secret information.

Several two-party protocols for quantum private comparison using entanglement and dense coding

Quantum private comparison (QPC) allows at least two participants who do not trust each other to compare whether their secret data are the same while maintaining data privacy, in which the security is based on the principles of quantum mechanics. In this paper, we propose several QPC protocols using Bell states, genuinely entangled five-qubit states, four-qubit cluster states and χ-type states. In each of the proposed protocols, we use dense coding technology to make the qubit efficiency of the protocol reach 100%, which is much higher than that of most existing protocols. The quantum states acting as information carriers are transmitted through a circular path, which can effectively reduce resource consumption. Decoy photon technology and one-time-pad encryption are used to ensure the security of the proposed protocols, making both external and internal attacks invalid.

Survey on quantum information security

The security of classical cryptography based on computational complexity assumptions has been severely challenged with the rapid development of quantum computers and quantum algorithms. Quantum cryptography, which offers unconditional security based on some principles of quantum mechanics, has become a significant branch and hotspot in the field of modern cryptography research. In this paper, we review the research and development of several important and well-studied branches of quantum cryptography in terms of theory and experiment, including quantum key distribution, quantum secret sharing, quantum secure direct communication, quantum signature, and quantum private query. We also briefly review the research and development of some other branches which are currently in the stage of theoretical research but receive widespread concern from academia, including quantum private comparison, quantum anonymous voting, quantum secure multi-party summation, quantum sealed-bid auction, quantum public key cryptosystem, quantum key agreement, quantum dialogue, and quantum identity authentication. In addition, we discuss some open issues and future research directions for the branches referred to above.

Two-party quantum private comparison protocol with maximally entangled seven-qubit state

Quantum private comparison (QPC), whose security is based on some laws of quantum mechanics (e.g. quantum noncloning theorem and Heisenbergs uncertainty principle), allows [Formula: see text] parties who do not trust each other to judge whether their secret data are the same while maintaining data privacy. In this paper, we investigate the utility of the maximally entangled seven-qubit state for QPC, and we propose a new protocol which enables two parties to compare their secret data with each other for equality without disclosing their secret data. In our protocol, single particle measurements and Bell-basis measurements are employed, both of which can be implemented with current technologies. In addition to quantum measurements, our protocol does not use other quantum technologies such as entanglement swapping and unitary operations. A semi-honest third-party who assists two parties in implementing the protocol is assumed in our protocol. Furthermore, we use the entanglement correlations of the maximally entangled seven-qubit state and collaborative computing between parties for privacy protection, and we use quantum key distribution (QKD) to ensure the security of the cooperative computing when two parties are in different locations. What is more, we show that the security towards both outsider and insider attacks can be guaranteed.

Semi-Quantum Key Agreement and Private Comparison Protocols Using Bell States

Semi-quantum protocol uses fewer resources and more flexible, which can still guarantee the unconditional safety. Based on Bell states, this paper first presents a semi-quantum key agreement protocol which allows two classical parties (Alice and Bob) to negotiate a shared secret key with the help of a quantum party (server). Classical parties only can perform reflection operation and measurement the qubit in the classical basis {|0〉, |1〉} in the protocol. During the protocol execution, Alice and Bob equally contribute in determining the final key and no one can manipulate and know the key prior to the other one. The security of the proposed protocol has been discussed, which analysis results show that the proposed protocol not only guarantees the security of the shared secret key but also assures the fairness property. We also analyze the efficiency of the proposed protocol. In addition, a semi-quantum private comparison protocol is proposed based on the key agreement protocol.

A Novel Pure Entangled State Based Two-Party Quantum Private Comparison Protocol

At present, the previous quantum private comparison (QPC) protocols always employ maximally entangled states as quantum resource, which are harder to prepare than pure entangled states. In this paper, by using two-particle pure entangled states as quantum resource, one novel QPC protocol is constructed, which is easy to implement in reality with present quantum technologies. The proposed protocol needs neither unitary operations nor quantum entanglement swapping but single-particle measurements. The proposed protocol is secure against both the outside attack and the participant attack.

A New Multi-Party Quantum Private Comparison Protocol Based on Circle Model

Recently multi-party quantum private comparison (MQPC) has attracted more and more attentions in the research of quantum cryptography. In our paper, a new MQPC protocol has been proposed by encoding the compared secrets on the phase of n-level single photons. From the proposed protocol, a generic model named circle model can be summarized. With the help of a semi-honest third party (TP), it can be proved that our protocol is immune to the outside attack and dishonest participants’ (including TP) attack.

A Novel and Efficient Quantum Private Comparison Scheme

A quantum private comparison is a primitive protocol of secure multiparty quantum computation that enables two parties to privately decide whether x = y or not, given two integers x and y, that are held as private inputs by the two parties, respectively. However, many existing quantum private comparison schemes may not be efficient enough, especially applied in big-data and large-scale network environments, because of low efficiency bit-by-bit comparisons. In this paper, we present a novel and efficient quantum private comparison scheme. The proposed scheme provides higher communication efficiency because a secret-by-secret comparison instead of a bit-by-bit comparison is used.