Identity-based ring signature scheme based on quadratic residues

Identity-based （ID-based） ring signature has drawn great concerns in recent years and many ID-based ring signature schemes have been proposed until now. Unfortunately, all of these ID-based ring signatures are constructed from bilinear pairings, a powerful but computationally expensive primitive. Hence, ID-based ring signature without pairing is of great interest in the field of cryptography. In this paper, the authors firstly propose an ID-based ring signature scheme based on quadratic residues. The proposed scheme is proved to be existentially unforgeable against adaptive chosen message-and-identity attack under the random oracle model, assuming the hardness of factoring. The proposed scheme is more efficient than those which are constructed from bilinear pairings.

A new improved ID-based proxy ring signature scheme from bilinear pairings

Ring signature and proxy signature are of vital importance to secure electronic commerce. Recently, the bilinear pairing such as Well pairing or Tate pairing on elliptic curves and hyperelliptic curves is playing an important role in security solutions. Several ID-based signature schemes have been put forward, many of which are based on bilinear pairings. In key management and moderate security demand scenarios, ID-based public key cryptosystem is more preferable than other public key infrastructure based systems. In this paper, an improved ID-based proxy ring signature scheme from bilinear pairings is proposed which combines the advantages of proxy signature and of ring signatures. Our scheme can guarantee the profits of the proxy signer via preventing the original signer form generating the proxy ring signature. Furthermore, bilinear pairings are introduced to minimize the computation overhead and to improve the related performance of our scheme. In contrast with Zhang＇s scheme, our scheme is a computational efficiency improvement for signature verification because the computational cost of bilinear pairings required is reduced from O（n） to O（ 1 ）. In addition, the proxy ring signature presented in this paper can perfectly satisfy all the security requirements of proxy ring signature, i. e. signer-ambiguity, non-forgeability, verification, non-deniability and distinguishability.

A Ring Signature Suitable for Wireless Sensor Networks

Wireless Sensor Network （WSN） nodes are severely limited by their power, communication bandwidth, and storage space, and the traditional signature algorithm is not suitable for WSN environments. In this paper, we present a ring signature scheme designed for WSNs. In this scheme, all of the wireless sensor nodes are divided into several sub-groups and the sub-group nodes are used to generate the signature instead of the WSN cluster nodes. This scheme can effectively avoid the single node failure problem, and it also has a high availability. All nodes are flee to sign their own message, and the nodes that generate signatures can simultaneously calculate their own part of the signature, meeting the distributed parallel computing requirements. Compared with the traditional ring signature, this scheme reduces the energy consumption, and therefore is very suitable for WSNs.

Threshold Ring Signature Scheme Based on TPM

The conventional ring signature schemes cannot address the scenario where the rank of members of the ring needs to be distinguished, for example, in electronically commerce application. To solve this problem, we presented a Trusted Platform Module （TPM）-based threshold ring signature schen. Employing a reliable secret Share Distribution Center （SDC）, the proposed approach can authenticate the TPM-based identity rank of members of the ring but not track a specific member＇s identity. A subset including t members with the same identity rank is built. With the signing cooperation of t members of the subset, the ring signature based on Chinese remainder theorem is generated. We proved the anonymity and unforgeability of the proposed scheme and compared it with the threshold ring signature based on Lagrange interpolation polynomial. Our scheme is relatively simpler to calculate.

An Efficient Certificateless Ring Signature Scheme

To overcome the drawbacks such as high computational cost, unreasonable security model and long signature length in existing certificateless ring signature schemes, we propose an efficient certificateless ring signature scheme in this paper. Our construction is inspired by some efficient ID-based ring signature schemes, and uses bilinear pairings as a basic tool. Using a reasonable security model, the unforgeability of the proposed scheme is proven based on the intractability of the computational Diffie-Hellman （CDH） problem. The signature length of the new scheme is only ｜G2｜＋n｜G1｜ （｜Gi｜ is the bit length of an element in group Gi, i =1, 2）. Compared with other existing certificateless ring signature schemes, the newly proposed scheme has a shorter signature length and is more efficient and practical.

A Conditionally Anonymous Linkable Ring Signature for Blockchain Privacy Protection

In recent years,the issue of preserving the privacy of parties involved in blockchain transactions has garnered significant attention.To ensure privacy protection for both sides of the transaction,many researchers are using ring signature technology instead of the original signature technology.However,in practice,identifying the signer of an illegal blockchain transaction once it has been placed on the chain necessitates a signature technique that offers conditional anonymity.Some illegals can conduct illegal transactions and evade the lawusing ring signatures,which offer perfect anonymity.This paper firstly constructs a conditionally anonymous linkable ring signature using the Diffie-Hellman key exchange protocol and the Elliptic Curve Discrete Logarithm,which offers a non-interactive process for finding the signer of a ring signature in a specific case.Secondly,this paper’s proposed scheme is proven correct and secure under Elliptic Curve Discrete Logarithm Assumptions.Lastly,compared to previous constructions,the scheme presented in this paper provides a non-interactive,efficient,and secure confirmation process.In addition,this paper presents the implementation of the proposed scheme on a personal computer,where the confirmation process takes only 2,16,and 24ms for ring sizes of 4,24 and 48,respectively,and the confirmation process can be combined with a smart contract on the blockchain with a tested millisecond level of running efficiency.In conclusion,the proposed scheme offers a solution to the challenge of identifying the signer of an illegal blockchain transaction,making it an essential contribution to the field.

A RING SIGNATURE SCHEME OVER BRAID GROUPS

Quantum algorithms bring great challenges to classical public key cryptosystems, which makes cryptosystems based on non-commutative algebraic systems hop topic. The braid groups, which are non-commutative, have attracted much attention as a new platform for constructing quantum attack-resistant cryptosystems. A ring signature scheme is proposed based on the difficulty of the root extraction problem over braid groups, which can resist existential forgery against the adaptively cho-sen-message attack under the random oracle model.

Feasibility analysis of two identity-based proxy ring signature schemes

Recently, proxy ring signature schemes have been shown to be useful in various applications, such as electronic polling, electronic payment, etc. Although many proxy ring signature schemes have been pro-posed, there are only two identity-based proxy ring signature schemes have been proposed until now, i. e., Cheng＇s scheme and Lang＇s scheme. It＇s unlucky that the two identity-based proxy ring signature schemes are unfeasible. This paper points out the reasons why the two identity-based proxy ring signature schemes are unfeasible. In order to design feasible and efficient identity-based proxy ring signature schemes from bilinear pairings, we have to search for other methods.

Revocable Ring Signature

Group signature allows the anonymity of a real signer in a group to be revoked by a trusted party called group manager. It also gives the group manager the absolute power of controlling the formation of the group. Ring signature, on the other hand, does not allow anyone to revoke the signer anonymity, while allowing the real signer to form a group （also known as a ring） arbitrarily without being controlled by any other party. In this paper, we propose a new variant for ring signature, called Revocable Ring Signature. The signature allows a real signer to form a ring arbitrarily while allowing a set of authorities to revoke the anonymity of the real signer. This new variant inherits the desirable properties from both group signature and ring signature in such a way that the real signer will be responsible for what it has signed as the anonymity is revocable by authorities while the real signer still has the freedom on ring formation. We provide a formal security model for revocable ring signature and propose an efficient construction which is proven secure under our security model.

An Attribute-Based Ring Signature Scheme in Lattice

An attribute-based ring signature scheme in lattice was proposed in this paper. In this signature scheme, an entity’s attributes correspond to the columns of a lattice matrix, and the signature was generated by using a subset of these attributes. The entities possessing these attributes form a ring. The scheme is computationally efficient than the schemes based on the integer factor problem and discrete logarithm problem, furthermore it is still secure in quantum computing environment.

Practical Constant-Size Ring Signature

Bitcoin has gained its popularity for almost 10 years as a ＂secure and anonymous digital currency＂. However, according to several recent researches, we know that it can only provide pseudonymity rather than real anonymity, and privacy has been one of the main concerns in the system similar to Bitcoin. Ring signature is a good method for those users who need better anonymity in cryptocurrency. It was first proposed by Rivest et al. based upon the discrete logarithm problem （DLP） assumption in 2006, which allows a user to sign a message anonymously on behalf of a group of users even without their coordination. The size of ring signature is one of the dominating parameters, and constant-size ring signature （where signature size is independent of the ring size） is much desirable. Otherwise, when the ring size is large, the resultant ring signature becomes unbearable for power limited devices or leads to heavy burden over the communication network. Though being extensively studied, currently there are only two approaches for constant-size ring signature. Achieving practical constant-size ring signature is a long-standing open problem since its introduction. In this work, we solve this open question. We present a new constant-size ring signature scheme based on bilinear pairing and accumulator, which is provably secure under the random oracle （RO） model. To the best of our knowledge, it stands for the most practical ring signature up to now.

Improved lattice-based ring signature schemes from basis delegation

Ring signature enables the members to sign anonymously without a manager, it has many online applications, such as e-voting, e-money, whistle blowing etc. As a promising post-quantum candidate, lattice-based cryptography attracts much attention recently. Several efficient lattice-based ring signatures have been naturally constructed from lattice basis delegation, but all of them have large verification key sizes. Our observation finds that a new concept called the split- small integer solution （SIS） problem introduced by Nguyen et al. at PKC＇I 5 is excellent in reducing the public key sizes of lattice-based ring signature schemes from basis delegation. In this research, we first define an extended concept called the extended split-SIS problem, and then prove that the hardness of the extended problem is as hard as the approximating shortest independent vectors problem （SIVP） problem within certain polynomial factor. Moreover, we present an improved ring signature and prove that it is anonymous and unforgeable against the insider corruption. Finally, we give two other improved existing ring signature schemes from lattices. In the end, we show the comparison with the original scheme in terms of the verification key sizes. Our research data illustrate that the public key sizes of the proposed schemes are reduced significantly.

RING PROXY SIGNATURES

Proxy signatures have been used to enable the transfer of digital signing power within some context and ring signatures can be used to provide the anonymity of a signer. By combining the functionalities of proxy signatures and ring signatures, this paper introduces a new concept, named ring proxy signature, which is a proxy signature generated by an anonymous member from a set of potential signers. The paper also constructs the first concrete ring proxy signature scheme based on the provably secure Schnorr's signatures and two ID-based ring proxy signature schemes. The security analysis is provided as well.

A linkable signature scheme supporting batch verification for privacy protection in crowd-sensing

The maturity of 5G technology has enabled crowd-sensing services to collect multimedia data over wireless network,so it has promoted the applications of crowd-sensing services in different fields,but also brings more privacy security challenges,the most commom which is privacy leakage.As a privacy protection technology combining data integrity check and identity anonymity,ring signature is widely used in the field of privacy protection.However,introducing signature technology leads to additional signature verification overhead.In the scenario of crowd-sensing,the existing signature schemes have low efficiency in multi-signature verification.Therefore,it is necessary to design an efficient multi-signature verification scheme while ensuring security.In this paper,a batch-verifiable signature scheme is proposed based on the crowd-sensing background,which supports the sensing platform to verify the uploaded multiple signature data efficiently,so as to overcoming the defects of the traditional signature scheme in multi-signature verification.In our proposal,a method for linking homologous data was presented,which was valuable for incentive mechanism and data analysis.Simulation results showed that the proposed scheme has good performance in terms of security and efficiency in crowd-sensing applications with a large number of users and data.

A Trust Value Sharing Scheme in Heterogeneous Identity Federation Topologies

Recent developments in heterogeneous identity federation systems have heightened the need for the related trust management system.The trust management system evaluates,manages,and shares users’trust values.The service provider(SP)members of the federation system rely on users’trust values to determine which type and quality of service will be provided to the users.While identity federation systems have the potential to help federated users save time and energy and improve service experience,the benefits also come with significant privacy risks.So far,there has been little discussion about the privacy protection of users in heterogeneous identity federation systems.In this paper,we propose a trust value sharing scheme based on a proxy ring signature for the trust management system in heterogeneous identity federation topologies.The ring signature schemes can ensure the validity of the data and hide the original signer,thereby protecting privacy.Moreover,no group manager participating in the ring signature,which naturally matches with our decentralized heterogeneous identity federation topologies.The proxy signature can reduce the workload of the private key owner.The proposed scheme shortens the calculation time for verifying the signature and then reduces the overall time consumption in the process of trust sharing.Our studies prove that the proposed scheme is privacy-preserving,efficient,and effective.

Anonymous TollPass: A Blockchain-Based Privacy-Preserving Electronic Toll Payment Model

As big data,Artificial Intelligence,and Vehicle-to-Everything(V2X)communication have advanced,Intelligent Transportation Systems(ITS)are being developed to enable efficient and safe transportation systems.Electronic Toll Collection(ETC),which is one of the services included in ITS systems,is an automated system that allows vehicles to pass through toll plazas without stopping for manual payment.The ETC system is widely deployed on highways due to its contribution to stabilizing the overall traffic system flow.To ensure secure and efficient toll payments,designing a distributed model for sharing toll payment information among untrusted toll service providers is necessary.However,the current ETC system operates under a centralized model.Additionally,both toll service providers and toll plazas know the toll usage history of vehicles.It raises concerns about revealing the entire driving routes and patterns of vehicles.To address these issues,blockchain technology,suitable for secure data management and data sharing in distributed systems,is being applied to the ETC system.Blockchain enables efficient and transparent management of ETC information.Nevertheless,the public nature of blockchain poses a challenge where users’usage records are exposed to all participants.To tackle this,we propose a blockchain-based toll ticket model named AnonymousTollPass that considers the privacy of vehicles.The proposed model utilizes traceable ring signatures to provide unlinkability between tickets used by a vehicle and prevent the identity of the vehicle using the ticket from being identified among the ring members for the ticket.Furthermore,malicious vehicles’identities can be traced when they attempt to reuse tickets.By conducting simulations,we show the effectiveness of the proposed model and demonstrate that gas fees required for executing the proposed smart contracts are only 10%(when the ring size is 50)of the fees required in previous studies.

Blockchain-based Privacy-Preserving Group Data Auditing with Secure User Revocation

Progress in cloud computing makes group data sharing in outsourced storage a reality.People join in group and share data with each other,making team work more convenient.This new application scenario also faces data security threats,even more complex.When a user quit its group,remaining data block signatures must be re-signed to ensure security.Some researchers noticed this problem and proposed a few works to relieve computing overhead on user side.However,considering the privacy and security need of group auditing,there still lacks a comprehensive solution to implement secure group user revocation,supporting identity privacy preserving and collusion attack resistance.Aiming at this target,we construct a concrete scheme based on ring signature and smart contracts.We introduce linkable ring signature to build a kind of novel meta data for integrity proof enabling anonymous verification.And the new meta data supports secure revocation.Meanwhile,smart contracts are using for resisting possible collusion attack and malicious re-signing computation.Under the combined effectiveness of both signature method and blockchain smart contracts,our proposal supports reliable user revocation and signature re-signing,without revealing any user identity in the whole process.Security and performance analysis compared with previous works prove that the proposed scheme is feasible and efficient.

Smart Quarantine Environment Privacy through IoT Gadgets Using Blockchain

The coronavirus,formerly known as COVID-19,has caused massive global disasters.As a precaution,most governments imposed quarantine periods ranging from months to years and postponed significantfinancial obligations.Furthermore,governments around the world have used cutting-edge technologies to track citizens’activity.Thousands of sensors were connected to IoT(Internet of Things)devices to monitor the catastrophic eruption with billions of connected devices that use these novel tools and apps,privacy and security issues regarding data transmission and memory space abound.In this study,we suggest a block-chain-based methodology for safeguarding data in the billions of devices and sen-sors connected over the internet.Various trial secrecy and safety qualities are based on cutting-edge cryptography.To evaluate the proposed model,we recom-mend using an application of the system,a Raspberry Pi single-board computer in an IoT system,a laptop,a computer,cell phones and the Ethereum smart contract platform.The models ability to ensure safety,effectiveness and a suitable budget is proved by the Gowalla dataset results.

Blockchain-Based Privacy-Preserving Public Auditing for Group Shared Data

Cloud storage has been widely used to team work or cooperation devel-opment.Data owners set up groups,generating and uploading their data to cloud storage,while other users in the groups download and make use of it,which is called group data sharing.As all kinds of cloud service,data group sharing also suffers from hardware/software failures and human errors.Provable Data Posses-sion(PDP)schemes are proposed to check the integrity of data stored in cloud without downloading.However,there are still some unmet needs lying in auditing group shared data.Researchers propose four issues necessary for a secure group shared data auditing:public verification,identity privacy,collusion attack resis-tance and traceability.However,none of the published work has succeeded in achieving all of these properties so far.In this paper,we propose a novel block-chain-based ring signature PDP scheme for group shared data,with an instance deployed on a cloud server.We design a linkable ring signature method called Linkable Homomorphic Authenticable Ring Signature(LHARS)to implement public anonymous auditing for group data.We also build smart contracts to resist collusion attack in group auditing.The security analysis and performance evalua-tion prove that our scheme is both secure and efficient.

Analysis and Improvement of Authenticatable Ring Signcryption Scheme

We show that the Zhang-Yang-Zhu-Zhang identity-based authenticatable ring signcryption scheme is not secure against chosen plaintext attacks.Furthermore, we propose an improved scheme that remedies the weakness of the Zhang-Yang-Zhu-Zhang scheme.The improved scheme has shorter ciphertext size than the Zhang-Yang-Zhu-Zhang scheme.We then prove that the improved scheme satisfies confidentiality, unforgeability, anonymity and authenticatability.