Efficient Group Signature Research Articles

An efficient group signature based certificate less verification scheme for vehicular ad-hoc network

An efficient group signature based certificate less verification scheme for vehicular ad-hoc network

Efficient and privacy-preserving group signature for federated learning

Federated Learning (FL) is a Machine Learning (ML) technique that aims to reduce the threats to user data privacy. Training is done using the raw data on the users’ devices, called clients. Only the training results, called gradients, are sent to the server to be aggregated which is used to generate an updated model. However, we cannot assume that the server can be trusted with the sensitive information, such as metadata related to the owner or source of the data. So, hiding client information from the server helps in reducing privacy-related attacks. Therefore, the privacy of the client’s identity, along with the privacy of the client’s data, is necessary to prevent such attacks. This paper proposes an efficient and privacy-preserving protocol for FL based on group signatures. A new group signature for federated learning, called GSFL, is designed to not only protect the privacy of the client’s data and identity but also significantly reduce the computation and communication costs considering the iterative process of federated learning. We show that GSFL outperforms existing approaches in terms of computation, communication, and signaling costs. Also, we show that the proposed protocol can handle various security attacks in the federated learning environment. Moreover, we provide security proof of our protocol using a formal security verification tool, Automated Validation of Internet Security Protocols and Applications (AVISPA).

Group signatures and more from isogenies and lattices: generic, simple, and efficient

We construct an efficient dynamic group signature (or more generally an accountable ring signature) from isogeny and lattice assumptions. Our group signature is based on a simple generic construction that can be instantiated by cryptographically hard group actions such as the CSIDH group action or an MLWE-based group action. The signature is of size O(log N), where N is the number of users in the group. Our idea builds on the recent efficient OR-proof by Beullens, Katsumata, and Pintore (Asiacrypt’20), where we efficiently add a proof of valid ciphertext to their OR-proof and further show that the resulting non-interactive zero-knowledge proof system is online extractable. Our group signatures satisfy more ideal security properties compared to previously known constructions, while simultaneously having an attractive signature size. The signature size of our isogeny-based construction is an order of magnitude smaller than all previously known post-quantum group signatures (e.g., 6.6 KB for 64 members). In comparison, our lattice-based construction has a larger signature size (e.g., either 126 KB or 89 KB for 64 members depending on the satisfied security property). However, since the O(cdot )-notation hides a very small constant factor, it remains small even for very large group sizes, say 2^{20}.

Efficient and Privacy Preserving Group Signature for Federated Learning

Efficient and Privacy Preserving Group Signature for Federated Learning

An Efficient Signature Scheme Based on Mobile Edge Computing in the NDN-IoT Environment

Named data networking (NDN) is an emerging information-centric networking paradigm, in which the Internet of Things (IoT) achieves excellent scalability. Recent literature proposes the concept of NDN-IoT, which maximizes the expansion of IoT applications by deploying NDN in the IoT. In the NDN, the security is built into the network by embedding a public signature in each data package to verify the authenticity and integrity of the content. However, signature schemes in the NDN-IoT environment are facing several challenges, such as signing security challenge for resource-constrained IoT end devices (EDs) and verification efficiency challenge for NDN routers. This article mainly studies the data package authentication scheme in the package-level security mechanism. Based on mobile edge computing (MEC), an efficient certificateless group signature scheme featured with anonymity, unforgeability, traceability, and key escrow resilience is proposed. The regional and edge architecture is utilized to solve the device management problem of IoT, reducing the risks of content pollution attacks from the data source. By offloading signature pressure to MEC servers, the contradiction between heavy overhead and shortage of ED resources is avoided. Moreover, the verification efficiency in NDN router is much improved via batch verification in the proposed scheme. Both security analysis and experimental simulations show that the proposed MEC-based certificateless group signature scheme is provably secure and practical.

Efficient Dynamic Group Signature Scheme with Verifier Local Revocation and Time-Bound Keys using Lattices

Revocation is an important feature of group signature schemes. Verifier Local Revocation (VLR) is a popular revocation mechanism which involves only verifiers in the revocation process. In VLR, a revocation list is maintained to store the information about revoked users. The verification cost of VLR based schemes islinearly proportional to the size of recvocation list. In many applications, the size of revocation list grows with time, which makes the verification process expensive. In this paper, we propose a lattice based dynamic group signature using VLR and time bound keys to reduce the size of revocation list to speed up the verification process. In the proposed scheme, an expiration date is fixed for signing key of each group member, and verifiers can find out (at constantcost) if a signature is generated using an expired key. Hence revocation information of members who are revoked before signing key expiry date (premature revocation) are kept in revocation list, and other members are part of natural revocation. This leads to a significant saving on the revocation check by assuming natural revocation accounts for large fraction of the total revocation. This scheme also takes care of non-forgeability of signing key expiry date.

A secure and efficient group signature scheme based on multivariate public key cryptography

Group signatures are significant primitive for anonymity, which allow group members to sign messages while hiding in the group, however, the signers remain accountable. Most of the existing schemes on group signature are relying on traditional cryptographic primitives, whereas rapid advancements in quantum computing suggest an originating threat to usual cryptographic primitives. This makes the necessity of quantum computer resistant cryptographic primitives. Multivariate public key cryptography (MPKC) is one of the promising options that may withstand quantum attacks. Its constructions are potential candidates for post-quantum (PQ) cryptography as they are very fast and require only modest computational resources. There are many existing secure and practical multivariate digital signatures. However, there is a deficiency of more advanced multivariate group signature scheme. The existing multivariate group signature has weaknesses in terms of security and efficiency. This paper introduces a new multivariate group signature scheme employing a 5-pass identification protocol and multivariate signature scheme as its building blocks. The proposed signature scheme possesses unforgeability, user’s anonymity, unlinkability, exculpability and traceability property. Unlike most of the existing post-quantum group signatures, the sizes of the signatures and the public parameters are not dependent on the number of group users in our construction. It depends only on the security parameters. In particular, our construction is the first MPKC based group signature, where signature size and public parameter size are independent of the number of group users.

Efficient Short Group Signatures for Conditional Privacy in Vehicular Ad Hoc Networks via ID Caching and Timed Revocation

Vehicular Ad hoc Networks (VANETs) are a subset of the Internet of Things (IoT) that are used in smart traffic applications. Due to their high speed, mobility, and exposure to the environment, the security requirements for VANETs result in the conflicting design goals of protecting member privacy while also ensuring non-repudiation. Group signature schemes can fulfill these requirements, but often at the cost of expensive bilinear pairing operations. Furthermore, the cost of updating the group key information can be costly. Accordingly, this paper has two goals. First, it presents a group signature scheme that has been modified to remove pairing operations by caching computed values, while still preserving the critical requirement of conditional privacy. Second, this paper presents an argument for the abandonment of perfect forward and backward secrecy in VANET schemes in order to prevent the generation of keys that are never used, or used only once, and reduce the twin burdens of excessive key recalculation and key redistribution on the system.

Publicly Verifiable Shared Dynamic Electronic Health Record Databases With Functional Commitment Supporting Privacy-Preserving Integrity Auditing

Electronic health record (EHR) is a system that collects patients' digital health information and shares it with other healthcare providers in the cloud. Since EHR contains a large amount of significant and sensitive information about patients, it is required that the system ensures response correctness and storage integrity. Meanwhile, with the rise of IoT, more low-performance terminals are deployed for receiving and uploading patient data to the server, which increases the computational and communication burden of the EHR systems. The verifiable database (VDB), where a user outsources his large database to a cloud server and makes queries once he needs certain data, is proposed as an efficient updatable cloud storage model for resource-constrained users. To improve efficiency, most existing VDB schemes utilize proof reuse and proof updating technique to prove correctness of the query results. However, it ignores the “real-time” of proof generation, which results in an overhead that the user has to perform extra process (e.g., auditing schemes) to check storage integrity. In this article, we propose a publicly verifiable shared updatable EHR database scheme that supports privacy-preserving and batch integrity checking with minimum user communication cost. We modify the existing functional commitment (FC) scheme for the VDB design and construct a concrete FC under the computational <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> -BDHE assumption. In addition, the use of an efficient verifier-local revocation group signature scheme makes our scheme support dynamic group member operations, and gives nice features, such as traceability and non-frameability.

An efficient full dynamic group signature scheme over ring

The group signature scheme is an important primitive in cryptography, it allows members in a group to generate signatures anonymously on behalf of the whole group. In view of the practical application of such schemes, it is necessary to allow users’ registration and revocation when necessary, which makes the construction of dynamic group signature schemes become a significant direction. On the basis of (Ling et al., Lattice-based group signatures: achieving full dynamicity with ease, 2017), we present the first full dynamic group signature scheme over ring, and under the premise of ensuring security, the efficiency of the scheme is improved mainly from the following three aspects: the size of keys, the dynamic construction of a Merkle hash tree that used to record the information of registered users, and the reuse of the leaves in this tree. In addition, the public and secret keys of both group manager and trace manager are generated by a trusted third party, which prevents the situation that the two managers generate their respective public key and secret key maliciously. Compared with the counterpart of the scheme in (Ling et al., Lattice-based group signatures: achieving full dynamicity with ease, 2017) over ring, the expected space complexity of the Merkle tree used in our work down almost by half, and the computational complexity of its update has been reduced by a notch because of the dynamic construction of the hash tree.

An efficient linkable group signature for payer tracing in anonymous cryptocurrencies

Abstract Cryptocurrencies, led by bitcoin launched in 2009, have obtained wide attention in recent years. Anonymous cryptocurrencies are highly essential since users need to preserve their privacy when conducting transactions. However, some users might misbehave with the cover of anonymity such as rampant trafficking or extortion. Thus, it is important to balance anonymity and accountability of anonymous cryptocurrencies. In this paper, we address this issue by proposing a linkable group signature for signing cryptocurrency transactions, which can be used to trace a payer’s identity in consortium blockchain based anonymous cryptocurrencies, in case a payer misbehaves in the system. The anonymity can be retained if a user behaves honestly. We prove that the proposed scheme achieves full-anonymity, full-traceability and linkability in the random oracle model. Implementation of the proposed linkable group signature scheme demonstrates its high efficiency and thus, can be adopted in anonymous cryptocurrencies in reality.

Lattice-based group signatures: Achieving full dynamicity (and deniability) with ease

Lattice-based group signature is an active research topic in recent years. Since the pioneering work by Gordon et al. (2010) [20], eight other schemes have been proposed, providing various improvements in terms of security, efficiency and functionality. However, most of the existing constructions work only in the static setting where the group population is fixed at the setup phase. The only two exceptions are the schemes by Langlois et al. (2014) [27] that handles user revocations (but new users cannot join), and by Libert et al. (2016) [28,29] which addresses the orthogonal problem of dynamic user enrollments (but users cannot be revoked).In this work, we provide the first lattice-based group signature that offers full dynamicity (i.e., users have the flexibility in joining and leaving the group), and thus, resolve a prominent open problem posed by previous works. Moreover, we achieve this non-trivial feat in a relatively simple manner. Starting with Libert et al.'s fully static construction (2016) [30] - which is arguably the most efficient lattice-based group signature to date, we introduce simple-but-insightful tweaks that allow to upgrade it directly into the fully dynamic setting. More startlingly, our scheme even produces slightly shorter signatures than the former, thanks to an adaptation of a technique proposed by Ling et al. (2013) [35], allowing to prove inequalities in zero-knowledge. The scheme satisfies the strong security requirements of Bootle et al.'s model (2016) [7], under the Short Integer Solution (SIS) and the Learning With Errors (LWE) assumptions.Furthermore, we demonstrate how to equip the obtained group signature scheme with the deniability functionality in a simple way. This attractive functionality, put forward by Ishida et al. (2016) [22], enables the tracing authority to provide an evidence that a given user is not the owner of a signature in question. In the process, we design a zero-knowledge protocol for proving that a given LWE ciphertext does not decrypt to a particular message.

Group signature with restrictive linkability: minimizing privacy exposure in ubiquitous environment

As IoT technology evolves, developments of ubiquitous computing accelerates. At the same time, threats of privacy exposure also increase since the IoT systems expose the information such as user’s location or medical status collected from all sorts of things. To handle the data elaborately, the ubiquitous systems need to employ a technology that provides anonymity to prevent exposure of personal information. The group signature scheme is widely used for a cryptographic base for privacy protection which do not reveal user’s identity but prove that he/she is a legitimate user. Recently, a number of researches concerning the basic group signature schemes with a differentiated linkability have been conducted to provide a more flexible service. However, existing researches focused on providing flexible services from the service provider’s position. The systems are exposed to high possibilities of unnecessary breach of privacy. In this paper, we define a restrictive linkability for the anonymous services that require an adequate linkability with a minimum user-designated privacy exposure in anonymous services and propose an efficient group signature scheme providing restrictive linkability.

Efficient Ring Signature and Group Signature Schemes Based on q-ary Identification Protocols

Efficient Ring Signature and Group Signature Schemes Based on q-ary Identification Protocols

Lattice-based group signature with verifier-local revocation

Among several post quantum primitives proposed in the past few decades, lattice-based cryptography is considered as the most promising one, due to its underlying rich combinatorial structure, and the worst-case to average-case reductions. The first lattice-based group signature scheme with verifier-local revocation (VLR) is treated as the first quantum-resistant scheme supported member revocation, and was put forward by Langlois et al. This VLR group signature (VLR-GS) has group public key size of O(nm log N log q), and a signature size of O(tm logN log q log β). Nguyen et al. constructed a simple efficient group signature from lattice, with significant advantages in bit-size of both the group public key and the signature. Based on their work, we present a VLR-GS scheme with group public key size of O(nm log q) and signature size of O(tm log q). Our group signature has notable advantages: support of membership revocation, and short in both the public key size and the signature size.

An Efficient Dynamic Group Signature with Non-frameability

A group signature scheme allows any member to sign on behalf of a group. It is applied to practical distributed security communication environments, such as privacy-preserving, data mining. In particular, the excellent features of group signatures, including membership joining and revocation, anonymity, traceability, non-frameability and controllable linkability, make group signature scheme more attractive. Among these features, non-frameability can guarantee that a members signature cannot be forged by any other (including issuer), and controllable linkability supports to confirm whether or not two group signatures are created by the same signer while preserving anonymity. Until now, only Hwang et al.s group schemes (proposed in 2013 and 2015) can support all of these features. In this paper, we present a new dynamic group signature scheme which can achieve all of the above excellent features. Compared with their schemes, our scheme has the following advantages. Firstly, our scheme achieves more efficient membership revocation, signing and verifying. The cost of update key in our scheme is two-thirds of them. Secondly, the tracing algorithm is simpler, since the signer can be determined without the judging step. Furthermore, in our scheme, the size of group public key and members private key are shorter. Lastly, we also prove security features of our scheme, such as anonymity, traceability, non-frameability, under a random oracle model.

Simpler Efficient Group Signature Scheme with Verifier-Local Revocation from Lattices

Simpler Efficient Group Signature Scheme with Verifier-Local Revocation from Lattices

An Efficient Revocable Group Signature Scheme in Vehicular Ad Hoc Networks

Although many revocable group signature schemes has been proposed in vehicular ad hoc networks (VANETs), the existing schemes suffer from long computation delay on revocation that they cannot adapt to the dynamic VANETs. Based on Chinese remainder theorem and Schnorr signature algorithm, this paper proposes an efficient revocable group signature scheme in VANETs. In the proposed scheme, it only need to update the corresponding group public key when a member quits the group, and in the meanwhile the key pairs of unchanged group members are not influenced. Furthermore, this scheme can achieve privacy protection by making use of blind certificates. Before joining to the VANETs, users register at local trusted agencies (LTAs) with their ID cards to obtain blind certificates. The blind certificate will be submitted to road-side units (RSUs) to verify the legality of users. Thus, the real identities of users can be protected. In addition, if there is a dispute, users can combine to submit open applications to RSUs against a disputed member. And LTAs can determine the real identity of the disputed member. Moreover, since the key pairs employed by a user are different in different groups, attackers are not able to track the movement of users with the obtained public keys in a group. Furthermore, performance analysis shows that proposed scheme has less computation cost than existing schemes.

Privacy-preserving security solution for cloud services

We propose a novel privacy-preserving security solution for cloud services. Our solution is based on an efficient nonbilinear group signature scheme providing the anonymous access to cloud services and shared storage servers. The novel solution offers anonymous authenticationfor registered users. Thus, users' personal attributes (age, valid registration, successful payment) can be proven without revealing users' identity, and users can use cloud services without any threat of profiling their behavior. However, if a user breaks provider's rules, his access right is revoked.Our solution provides anonymous access, unlinkability and the confidentiality of transmitted data. We implement our solution as a proof of concept applicationand present the experimental results. Further, we analyzecurrent privacy preserving solutions for cloud services and group signature schemes as basic parts of privacy enhancing solutions in cloud services. We compare the performance of our solution with the related solutionsand schemes.

Efficient group signatures for privacy-preserving vehicular networks

In this paper, we deal with efficient group signatures employed in secure and privacy-preserving vehicular networks. Our solution aims to minimize the impact of several common attacks like denial of services or replay attacks on the efficiency of privacy-preserving security solutions in vehicular networks. Due to advanced properties like a short-term linkability and a categorized batch verification, our solution based on group signatures ensures privacy, security and the efficiency of vehicular networks which can be attacked by malicious parties. We outline the proposed communication pattern of vehicular networks, our security solution in detail, a formal security analysis and the experimental implementation of our solution. In addition, we evaluate and compare our solution with related works. Our group signature scheme is more efficient and secure in the signing phase and in the verification phase than related schemes.