Block Verification Mechanism Based on Zero-Knowledge Proof in Blockchain

Since transactions in blockchain are based on public ledger verification,this raises security concerns about privacy protection.And it will cause the accumulation of data on the chain and resulting in the low efficiency of block verification,when the whole transaction on the chain is verified.In order to improve the efficiency and privacy protection of block data verification,this paper proposes an efficient block verification mechanism with privacy protection based on zeroknowledge proof(ZKP),which not only protects the privacy of users but also improves the speed of data block verification.There is no need to put the whole transaction on the chain when verifying block data.It just needs to generate the ZKP and root hash with the transaction information,then save them to the smart contract for verification.Moreover,the ZKP verification in smart contract is carried out to realize the privacy protection of the transaction and efficient verification of the block.When the data is validated,the buffer accepts the complete transaction,updates the transaction status in the cloud database,and packages up the chain.So,the ZKP strengthens the privacy protection ability of blockchain,and the smart contracts save the time cost of block verification.

Privacy-preserving analytics for the securitization market: a zero-knowledge distributed ledger technology application

A zero-knowledge proof or protocol is a cryptographic technique for verifying private data without revealing it in its clear form.In this paper,we evaluate the potential for zero-knowledge distributed ledger technology to alleviate asymmetry of information in the asset-backed securitization market.To frame this inquiry,we conducted market data analyses,a review of prior literature,stakeholder interviews with investors,originators and security issuers and collaboration with blockchain engineers and researchers.We introduce a new system which could enable all market participants in the securitization lifecycle(e.g.investors,rating agencies,regulators and security issuers)to interact on a unique decentralized platform while maintaining the privacy of loan-level data,therefore providing the industry with timely analytics and performance data.Our platform is powered by zkLedger(Narula et al.2018),a zero-knowledge protocol developed by the MIT Media Lab and the first system that enables participants of a distributed ledger to run publicly verifiable analytics on masked data.

A Blockchain-Based Proxy Re-Encryption Scheme with Conditional Privacy Protection and Auditability

With the development of Internet of Things technology,intelligent door lock devices are widely used in the field of house leasing.In the traditional housing leasing scenario,problems of door lock information disclosure,tenant privacy disclosure and rental contract disputes frequently occur,and the security,fairness and auditability of the housing leasing transaction cannot be guaranteed.To solve the above problems,a blockchain-based proxy re-encryption scheme with conditional privacy protection and auditability is proposed.The scheme implements fine-grained access control of door lock data based on attribute encryption technology with policy hiding,and uses proxy re-encryption technology to achieve auditable supervision of door lock information transactions.Homomorphic encryption technology and zero-knowledge proof technology are introduced to ensure the confidentiality of housing rent information and the fairness of rent payment.To construct a decentralized housing lease transaction architecture,the scheme realizes the efficient collaboration between the door lock data ciphertext stored under the chain and the key information ciphertext on the chain based on the blockchain and InterPlanetary File System.Finally,the security proof and computing performance analysis of the proposed scheme are carried out.The results show that the scheme can resist the chosen plaintext attack and has low computational cost.

A Fair and Trusted Trading Scheme for Medical Data Based on Smart Contracts

Data is regarded as a valuable asset,and sharing data is a prerequisite for fully exploiting the value of data.However,the current medical data sharing scheme lacks a fair incentive mechanism,and the authenticity of data cannot be guaranteed,resulting in low enthusiasm of participants.A fair and trusted medical data trading scheme based on smart contracts is proposed,which aims to encourage participants to be honest and improve their enthusiasm for participation.The scheme uses zero-knowledge range proof for trusted verification,verifies the authenticity of the patient’s data and the specific attributes of the data before the transaction,and realizes privacy protection.At the same time,the game pricing strategy selects the best revenue strategy for all parties involved and realizes the fairness and incentive of the transaction price.The smart contract is used to complete the verification and game bargaining process,and the blockchain is used as a distributed ledger to record the medical data transaction process to prevent data tampering and transaction denial.Finally,by deploying smart contracts on the Ethereum test network and conducting experiments and theoretical calculations,it is proved that the transaction scheme achieves trusted verification and fair bargaining while ensuring privacy protection in a decentralized environment.The experimental results show that the model improves the credibility and fairness of medical data transactions,maximizes social benefits,encourages more patients and medical institutions to participate in the circulation of medical data,and more fully taps the potential value of medical data.

A Blockchain-Based Efficient Cross-Domain Authentication Scheme for Internet of Vehicles

The Internet of Vehicles(IoV)is extensively deployed in outdoor and open environments to effectively address traffic efficiency and safety issues by connecting vehicles to the network.However,due to the open and variable nature of its network topology,vehicles frequently engage in cross-domain interactions.During such processes,directly uploading sensitive information to roadside units for interaction may expose it to malicious tampering or interception by attackers,thus compromising the security of the cross-domain authentication process.Additionally,IoV imposes high real-time requirements,and existing cross-domain authentication schemes for IoV often encounter efficiency issues.To mitigate these challenges,we propose CAIoV,a blockchain-based efficient cross-domain authentication scheme for IoV.This scheme comprehensively integrates technologies such as zero-knowledge proofs,smart contracts,and Merkle hash tree structures.It divides the cross-domain process into anonymous cross-domain authentication and safe cross-domain authentication phases to ensure efficiency while maintaining a balance between efficiency and security.Finally,we evaluate the performance of CAIoV.Experimental results demonstrate that our proposed scheme reduces computational overhead by approximately 20%,communication overhead by around 10%,and storage overhead by nearly 30%.

A Cloud-Fog Enabled and Privacy-Preserving IoT Data Market Platform Based on Blockchain

The dynamic landscape of the Internet of Things(IoT)is set to revolutionize the pace of interaction among entities,ushering in a proliferation of applications characterized by heightened quality and diversity.Among the pivotal applications within the realm of IoT,as a significant example,the Smart Grid(SG)evolves into intricate networks of energy deployment marked by data integration.This evolution concurrently entails data interchange with other IoT entities.However,there are also several challenges including data-sharing overheads and the intricate establishment of trusted centers in the IoT ecosystem.In this paper,we introduce a hierarchical secure data-sharing platform empowered by cloud-fog integration.Furthermore,we propose a novel non-interactive zero-knowledge proof-based group authentication and key agreement protocol that supports one-to-many sharing sets of IoT data,especially SG data.The security formal verification tool shows that the proposed scheme can achieve mutual authentication and secure data sharing while protecting the privacy of data providers.Compared with previous IoT data sharing schemes,the proposed scheme has advantages in both computational and transmission efficiency,and has more superiority with the increasing volume of shared data or increasing number of participants.

Delegateable signatures based on non-interactive witness indistinguishable and non-interactive witness hiding proofs

A delegateable signature scheme （DSS） which was first introduced by Barak is mainly based on the non-interactive zero-knowledge proof （NIZK） for preventing the signing verifier from telling which witness （i.e., restricted subset） is being used. However, the scheme is not significantly efficient due to the difficulty of constructing NIZK. We first show that a non-interactive witness indistinguishable （NlWl） proof system and a non-interactive witness hiding （NIWH） proof system are easier and more efficient proof models than NIZK in some cases. Furthermore, the witnesses em- ployed in these two protocols （NlWl and NIWT） cannot also be distinguished by the verifiers. Combined with the E-protocol, we then construct NlWl and NIWH proofs for any NP statement under the existence of one-way functions and show that each proof is different from those under the existence of trapdoor permutations, Finally, based on our NlWl and NIWH proofs, we construct delegateable signature schemes under the existence of one-way functions, which are more efficient than Barak＇s scheme under the existence of trapdoor permutations.

An Effective Security Comparison Protocol in Cloud Computing

With the development of cloud computing technology,more and more data owners upload their local data to the public cloud server for storage and calculation.While this can save customers’operating costs,it also poses privacy and security challenges.Such challenges can be solved using secure multi-party computation(SMPC),but this still exposes more security issues.In cloud computing using SMPC,clients need to process their data and submit the processed data to the cloud server,which then performs the calculation and returns the results to each client.Each client and server must be honest.If there is cooperation or dishonest behavior between clients,some clients may profit from it or even disclose the private data of other clients.This paper proposes the SMPC based on a Partially-Homomorphic Encryption(PHE)scheme in which an addition homomorphic encryption algorithm with a lower computational cost is used to ensure data comparability and Zero-Knowledge Proof(ZKP)is used to limit the client’s malicious behavior.In addition,the introduction of Oblivious Transfer(OT)technology also ensures that the semi-honest cloud server knows nothing about private data,so that the cloud server of this scheme can calculate the correct data in the case of malicious participant models and safely return the calculation results to each client.Finally,the security analysis shows that the scheme not only ensures the privacy of participants,but also ensures the fairness of the comparison protocol data.

Memorizable Interactive Proof and Zero-Knowledge Proof Systems

Interactive proof and zero-knowledge proof systems are two important concepts in cryptography and complexity theory. In the past two decades, a great number of interactive proof and zero-knowledge proof protocols have been designed and applied in practice. In this paper, a simple memorizable zero-knowledge protocol is proposed for graph non-isomorphism problem, based on the memorizable interactive proof system, which is extended from the original definition of interactive proof and is more applicable in reality. Keywords interactive proof - zero-knowledge proof - memorizable interactive proof - memorizable zero-knowledge proof This work was supported by the ministry of Science and Technology of China (Grant No.2001CCA03000), and the National Natural Science Foundation of China (Grant No.60273045).Ning Chen received his B.S. degree from Fudan University in 2001. Now he is a master candidate of Department of Computer Science, Fudan University. His research interests include computational complexity, computational cryptography, algorithm design and analysis.Jia-Wei Rong received her B.S. degree from Fudan University in 2002. Now she is a master candidate of Department of Computer Science, Fudan University. Her research interests include computational cryptography, machine learning, artificial intelligence.

BMSC:A Novel Anonymous Trading Scheme Based on Zero-Knowledge Proof in Ethereum

Blockchains are widely used because of their openness,transparency,nontampering and decentralization.However,there is a high risk of information leakage when trading on blockchain,and the existing anonymous trading schemes still have some problems.To meet the high requirement of anonymity,the cost of proof submitted by the user is too large,which does not apply to blockchain storage.Meanwhile,transaction verification takes too long to ensure the legitimacy of the transaction.To solve these problems,this paper presents a novel anonymous trading scheme named Block Maze Smart Contract(BMSC)based on the zeroknowledge proof system zk-SNARKs to propose efficiency.This scheme can hide account balances,transaction amounts,and the transfer relationships between transaction parties while preventing overspending attacks and double-spending attacks.Compared with other anonymous schemes,this scheme has less cost of proof and takes less time for transaction verification while meeting the high requirements of anonymity and security.

基于非交互式零知识证明的组签名方案(英文)

Non-Interactive Zero-Knowledge(NIZK for short) proofs are fascinating and extremely useful in many security protocols. In this paper,a new group signature scheme,decisional linear assumption group signature(DLAGS for short) with NIZK proofs is proposed which can prove and sign the multiple values rather than individual bits based on DLIN assumption. DLAGS does not need to interact between the verifier and issuer,which can decrease the communication times and storage cost compared with the existing interactive group signature schemes. We prove and sign the blocks of messages instead of limiting the proved message to only one bit(0 or 1) in the conventional non-interactive zero-knowledge proof system,and we also prove that our scheme satisfy the property of anonymity,unlinkability and traceability. Finally,our scheme is compared with the other scheme(Benoitt's scheme) which is also based on the NIZK proofs system and the DLIN assumption,and the results show that our scheme requires fewer members of groups and computational times.

Privacy Protection for Blockchains with Account and Multi-Asset Model

The blockchain technology has been applied to wide areas.However,the open and transparent properties of the blockchains pose serious challenges to users’privacy.Among all the schemes for the privacy protection,the zero-knowledge proof algorithm conceals most of the private information in a transaction,while participants of the blockchain can validate this transaction without the private information.However,current schemes are only aimed at blockchains with the UTXO model,and only one type of assets circulates on these blockchains.Based on the zero-knowledge proof algorithm,this paper proposes a privacy protection scheme for blockchains that use the account and multi-asset model.We design the transaction structure,anonymous addresses and anonymous asset metadata,and also propose the methods of the asset transfer and double-spending detection.The zk-SNARKs algorithm is used to generate and to verify the zero-knowledge proof.And finally,we conduct the experiments to evaluate our scheme.

A New Protocol for Multi-Item Electronic Auctions

The authors propose a new protocol for muhizzitem electronic auctions. It has the following advantages： first, the protocol is more applicable and flexible than the previous protocols, in this protocol, each bidder can decide how many items to buy according to diiferent bidding prices, which are set by the seller at the beginning of the auction; second, privacy is well preserved, no third parties are needed in the protocol and the auction outcome is jointly computed by the bidders on their own without uncovering any additional information.

Policy-Based Group Signature Scheme from Lattice

Although the existing group signature schemes from lattice have been optimized for efficiency,the signing abilities of eachmember in the group are relatively single.It may not be suitable for complex applications.Inspired by the pioneering work of Bellare and Fuchsbauer,we present a primitive called policy-based group signature.In policy-based group signatures,group members can on behalf of the group to sign documents that meet their own policies,and the generated signatures will not leak the identity and policies of the signer.Moreover,the group administrator is allowed to reveal the identity of signer when a controversy occurs.Through the analysis of application scenarios,we concluded that the policy-based group signature needs to meet two essential security properties:simulatability and traceability.And we construct a scheme of policy-based group signature from lattice through techniques such as commitment,zero-knowledge proof,rejection sampling.The security of our scheme is proved to be reduced to the module short integer solution(MSIS)and module learning with errors(MLWE)hard assumptions.Furthermore,we make a performance comparison between our scheme and three lattice-based group signature schemes.The result shows that our scheme has more advantages in storage overhead and the sizes of key and signature are decreased roughly by 83.13%,46.01%,respectively,compared with other schemes.

CompactChain:an efficient stateless chain for UTXO-model blockchain

In this work,we propose a stateless blockchain called CompactChain,which compacts the entire state of the UTXO(Unspent Transaction Output)based blockchain systems into two RSA accumulators.The first accumulator is called Transaction Output(TXO)commitment which represents the TXO set.The second one is called Spent Transaction Output(STXO)commitment which represents the STXO set.In this work,we discuss three algorithms:(i)To update the TXO and STXO commitments by the miner.The miner also provides the proofs for the correctness of the updated commitments;(ii)To prove the transaction’s validity by providing a membership witness in TXO commitment and non-membership witness against STXO commitment for a coin being spent by a user;(iii)To update the witness for the coin that is not yet spent;The experimental results evaluate the performance of the CompactChain in terms of time taken by a miner to update the commitments and time taken by a validator to verify the commitments and validate the transactions.We compare the performance of CompactChain with the existing state-of-the-art works on stateless blockchains.CompactChain shows a reduction in commitments update complexity and transaction witness size which inturn reduces the mempool size and propagation latency without compromising the system throughput(Transactions per second(TPS)).

Primitives towards verifiable computation： a survey

Verifiable computation （VC） paradigm has got the captivation that in real term is highlighted by the concept of third party computation. In more explicate terms, VC allows resource constrained clients/organizations to securely outsource expensive computations to untrusted service providers, while acquiring the publicly or privately verifiable results. Many mainstream solutions have been proposed to address the diverse problems within the VC domain. Some of them imposed assumptions over performed computations, while the others took advantage of interactivity /non-interactivity, zero knowledge proofs, and arguments. Further proposals utilized the powers of probabilistic checkable or computationally sound proofs. In this survey, we present a chronological study and classify the VC proposals based on their adopted domains. First, we provide a broader overview of the theoretical advancements while critically analyzing them. Subsequently, we present a comprehensive view of their utilization in the state of the art VC approaches. Moreover, a brief overview of recent proof based VC systems is also presented that lifted up the VC domain to the verge of practicality. We use the presented study and reviewed resuits to identify the similarities and alterations, modifications, and hybridization of different approaches, while comparing their advantages and reporting their overheads. Finally, we discuss implementation of such VC based systems, their applications, and the likely future directions.

A simplified scheme for secure offline electronic payment systems

This paper proposes a secure offline electronic(e-)payment scheme by adopting Schnorr’s untraceable blind signature(BS).Thereby,to satisfy the essential security requirements of e-payment systems,it requires much more simple computations and becomes more practical than many existing schemes.Other considerations are:to prevent the forgery of e-coin,the Bank is only the lawful entity to produce the valid e-coin;and others can verify its correctness.To confirm no swindling,the e-coin owner also sticks her private signing key with the e-coin before spending it as the payment.Hence,through the commitment with challenge-response of Schnorr’s BS,the merchant can verify the spent e-coin,and the trusted authority can identify the dishonest spender if multiple spending occurs.Moreover,it embeds three distinct information of date,namely expiration,deposit,and transaction dates with every e-coin.Thereby,it minimizes the size of the Bank’s database,correctly calculates the interest of the e-coin,and helps in arbiter if multiple spending,respectively.Finally,it evaluates the performance and analyzes essential security requirements of the proposed scheme,plus studies a comparison with existing ones.

Audit Scheme of University Scientific Research Funds Based on Consortium Blockchain

In the current process of university scientific research funding audits,the auditors do not obtain audit evidence in a timely manner,resulting in a lag in audit time;at the same time,there is the possibility that the audit evidence may be tampered with,and the sensitive expenditure cannot be effectively protected.Based on this,this paper proposes an audit scheme for university scientific research funds based on a consortium chain.The scheme saves relevant audit evidence through blockchain and IPFS,which changes the storage method of traditional audit evidence and effectively ensures the integrity,auditability of audit evidence and verifiability,and facilitates real-time auditing.We use Pedersen Commitment and Zero-Knowledge Range Proof to ensure the auditability of sensitive data;use smart contracts to automate auditing to further ensure that auditors can find relevant audit issues in a timely manner;and separate different departments and construct an audit tree through multi-channel technology to ensure the integrity and reliability of data and improve audit efficiency and accuracy.Finally,functional comparison analysis and security analysis show that the scheme in this paper has certain feasibility and robustness.