FL-EASGD:Federated Learning Privacy Security Method Based on Homomorphic Encryption

Federated learning ensures data privacy and security by sharing models among multiple computing nodes instead of plaintext data.However,there is still a potential risk of privacy leakage,for example,attackers can obtain the original data through model inference attacks.Therefore,safeguarding the privacy of model parameters becomes crucial.One proposed solution involves incorporating homomorphic encryption algorithms into the federated learning process.However,the existing federated learning privacy protection scheme based on homomorphic encryption will greatly reduce the efficiency and robustness when there are performance differences between parties or abnormal nodes.To solve the above problems,this paper proposes a privacy protection scheme named Federated Learning-Elastic Averaging Stochastic Gradient Descent(FL-EASGD)based on a fully homomorphic encryption algorithm.First,this paper introduces the homomorphic encryption algorithm into the FL-EASGD scheme to preventmodel plaintext leakage and realize privacy security in the process ofmodel aggregation.Second,this paper designs a robust model aggregation algorithm by adding time variables and constraint coefficients,which ensures the accuracy of model prediction while solving performance differences such as computation speed and node anomalies such as downtime of each participant.In addition,the scheme in this paper preserves the independent exploration of the local model by the nodes of each party,making the model more applicable to the local data distribution.Finally,experimental analysis shows that when there are abnormalities in the participants,the efficiency and accuracy of the whole protocol are not significantly affected.

Efficient semi-quantum secret sharing protocol using single particles

Semi-quantum secret sharing(SQSS)is a branch of quantum cryptography which only requires the dealer to have quantum capabilities,reducing the difficulty of protocol implementation.However,the efficiency of the SQSS protocol still needs to be further studied.In this paper,we propose a semi-quantum secret sharing protocol,whose efficiency can approach 100%as the length of message increases.The protocol is based on single particles to reduce the difficulty of resource preparation.Particle reordering,a simple but effective operation,is used in the protocol to improve efficiency and ensure security.Furthermore,our protocol can share specific secrets while most SQSS protocols could not.We also prove that the protocol is secure against common attacks.

A Novel Post-Quantum Blind Signature for Log System in Blockchain

In recent decades, log system management has been widely studied fordata security management. System abnormalities or illegal operations can befound in time by analyzing the log and provide evidence for intrusions. In orderto ensure the integrity of the log in the current system, many researchers havedesigned it based on blockchain. However, the emerging blockchain is facing significant security challenges with the increment of quantum computers. An attackerequipped with a quantum computer can extract the user's private key from thepublic key to generate a forged signature, destroy the structure of the blockchain,and threaten the security of the log system. Thus, blind signature on the lattice inpost-quantum blockchain brings new security features for log systems. In ourpaper, to address these, firstly, we propose a novel log system based on post-quantum blockchain that can resist quantum computing attacks. Secondly, we utilize apost-quantum blind signature on the lattice to ensure both security and blindnessof log system, which makes the privacy of log information to a large extent.Lastly, we enhance the security level of lattice-based blind signature under therandom oracle model, and the signature size grows slowly compared with others.We also implement our protocol and conduct an extensive analysis to prove theideas. The results show that our scheme signature size edges up subtly comparedwith others with the improvement of security level.

Rational Non-Hierarchical Quantum State Sharing Protocol

Rational participants want to maximize their benefits.The protocol with rational participants will be more realistic than the protocol with honest,semi-honest and dishonest participants.We research the rational non-hierarchical quantum state sharing in this paper.General steps of some known quantum state sharing protocol are summarized.Based on these steps,a new rational protocol is proposed.It means that lots of common protocols could be modified to rational protocols.Our protocol is widely applicable.Analyses show that the proposed protocol is rational and secure.It is also all-win for agents.Furthermore,number of deceiving agents is considered to redefine the utilities of agents.

Directional Modulation Based on a Quantum Genetic Algorithm for a Multiple-Reflection Model

Directional modulation is one of the hot topics in data security researches.To fulfill the requirements of communication security in wireless environment with multiple paths,this study takes into account the factors of reflections and antenna radiation pattern for directional modulation.Unlike other previous works,a novel multiple-reflection model,which is more realistic and complex than simplified two-ray reflection models,is proposed based on two reflectors.Another focus is a quantum genetic algorithm applied to optimize antenna excitation in a phased directional modulation antenna array.The quantum approach has strengths in convergence speed and the globe searching ability for the complicated model with the large-size antenna array and multiple paths.From this,a phased directional modulation transmission system can be optimized as regards communication safety and improve performance based on the constraint of the pattern of the antenna array.Our work can spur applications of the quantum evolutionary algorithm in directional modulation technology,which is also studied.

Cipherchain:A Secure and Efficient Ciphertext Blockchain via mPECK

Most existing blockchain schemes are based on the design concept“openness and transparency”to realize data security,which usually require transaction data to be presented in the form of plaintext.However,it inevitably brings the issues with respect to data privacy and operating performance.In this paper,we proposed a novel blockchain scheme called Cipherchain,which can process and maintain transaction data in the form of ciphertext while the characteristics of immutability and auditability are guaranteed.Specifically in our scheme,transactions can be encrypted locally based on a searchable encryption scheme called multi-user public key encryption with conjunctive keyword search(mPECK),and can be accessed by multiple specific participants after appended to the globally consistent distributed ledger.By introducing execution-consensus-update paradigm of transaction flow,Cipherchain cannot only make it possible for transaction data to exist in the form of ciphertext,but also guarantee the overall system performance not greatly affected by cryptographic operations and other local execution work.In addition,Cipherchain is a promising scheme to realize the technology combination of“blockchain+cloud computing”and“permissioned blockchain+public blockchain”.

Constructing the three-qudit unextendible product bases with strong nonlocality

Unextendible product bases(UPBs)are interesting members of a family of orthogonal product bases.Here,we investigate the construction of 3-qudit UPBs with strong nonlocality.First,a UPB set in C^(3)■C^(3)■C^(3)of size 19 is presented based on the shift UPBs.By mapping the system to a Rubik’s cube,we provide a general method of constructing UPBs in C^(d)■C^(d)■C^(d)of size(d-1)^(3)+2d+5,whose corresponding Rubik’s cube is composed of four parts.Second,for the more general case where the dimensions of parties are different,we extend the classical tile structure to the 3-qudit system and propose the tri-tile structure.By means of this structure,a C^(4)■C^(4)■C^(5)system of size 38 is obtained based on a C^(3)■C^(3)■C^(4)system of size 19.Then,we generalize this approach to the C^(d1)■C^(d2)■C^(d3)system which also consists of four parts.Our research provides a positive answer to the open question raised in by Halder et al.[Phys.Rev.Lett.122040403(2019)],indicating that there do exist UPBs that can exhibit strong quantum nonlocality without entanglement.

Data Anonymous Authentication for BIoMT with Proxy Group Signature

Along with the increase of wearable medical device,the privacy leakage problem in the process of transmission between these edge medical devices.The blockchain-enabled Internet of Medical Things(BIoMT)has been developed to reform traditional centralized medical system in recent years.This paper first introduces a data anonymous authentication model to protect user privacy and medical data in BIoMT.Then,a proxy group signature(PGS)scheme has been proposed based on lattice assumption.This scheme can well satisfy the anonymous authentication demand for the proposed model,and provide anti-quantum attack security for BIoMT in the future general quantum computer age.Moreover,the security analysis shows this PGS scheme is secure against the dynamical-almost-full anonymous and traceability.The efficiency comparison shows the proposed model and PGS scheme is more efficient and practical.

Blockchain data secure sharing protocol based on threshold Paillier algorithm

With the development of Internet technology,secure storage and secure sharing of data have become increasingly important.Traditional data sharing schemes exist a series of problems including lack of security and low efficiency.In this paper,we construct a secure and efficient data sharing scheme based on threshold Paillier algorithm and blockchain technology,which achieves secure data storage and sharing without a third-party institution.Firstly,we propose a(t,l)threshold Paillier blockchain data sharing scheme,which effectively prevents decryption failures caused by the loss of a single node’s private key.Secondly,we propose a combined on-chain and off-chain data storage scheme,we store the ciphertext on the cloud server and the ciphertext hash value on the blockchain,which not only ensures the integrity of the data but also solves the storage limitation problem on the blockchain.Finally,we use the simulation paradigm to prove the security of the scheme in the semi-honest model.The discussion results of the comparison and the analysis of performance show that the blockchain data security sharing scheme proposed in this paper has lower computational overhead and higher security than other similar schemes.

Robust QKD-based private database queries based on alternative sequences of single-qubit measurements

Quantum channel noise may cause the user to obtain a wrong answer and thus misunderstand the database holder for existing QKD-based quantum private query(QPQ) protocols. In addition, an outside attacker may conceal his attack by exploiting the channel noise. We propose a new, robust QPQ protocol based on four-qubit decoherence-free(DF) states. In contrast to existing QPQ protocols against channel noise, only an alternative fixed sequence of single-qubit measurements is needed by the user(Alice) to measure the received DF states. This property makes it easy to implement the proposed protocol by exploiting current technologies. Moreover, to retain the advantage of flexible database queries, we reconstruct Alice's measurement operators so that Alice needs only conditioned sequences of single-qubit measurements.

Improving the efficiency of quantum hash function by dense coding of coin operators in discrete-time quantum walk

Li et al. first proposed a quantum hash function(QHF) in a quantum-walk architecture. In their scheme, two two-particle interactions, i.e., I interaction and π-phase interaction are introduced and the choice of I or π-phase interactions at each iteration depends on a message bit. In this paper, we propose an efficient QHF by dense coding of coin operators in discrete-time quantum walk. Compared with existing QHFs, our protocol has the following advantages: the efficiency of the QHF can be doubled and even more; only one particle is enough and two-particle interactions are unnecessary so that quantum resources are saved. It is a clue to apply the dense coding technique to quantum cryptographic protocols, especially to the applications with restricted quantum resources.