Verifier-local Revocation Group Signature Research Articles

Verifier-local revocation group signatures with backward unlinkability from lattices

Verifier-local revocation group signatures with backward unlinkability from lattices

Almost Fully Secured Lattice-Based Group Signatures with Verifier-Local Revocation

An efficient member revocation mechanism is a desirable feature when group signature schemes are applied in practical scenarios. Revocation methods, such as verifier-local revocation (VLR), provide an efficient member revocation in applications of group signatures. However, VLR-group signatures rely on a weaker security notion. On the other hand, group signature schemes for static groups gain stronger security with the full-anonymity security notion. Even though an outsider sees the secret signing keys of all group members in the full-anonymity, the signer is still anonymous. Achieving the full-anonymity for VLR group signature schemes is challenging due to the structure of secret signing keys. The secret signing keys of those schemes consist of tokens, which are used to manage revocation. The reveal of tokens may destroy the anonymity of the signers. We obtain stronger security for the lattice-based VLR group signature schemes by providing a new key generation method, which outputs revocation tokens without deriving from the members’ secret signing keys. We propose a new group signature scheme from lattices with VLR, which achieves stronger security than the previous related works. To avoid signature forgeries, we suggest a new zero-knowledge proof system that requires signers to validate themselves. Moreover, we output an efficient tracing mechanism.

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.

A lattice-based group signature scheme with verifier-local revocation

Support of membership revocation is a desirable functionality for any group signature scheme. Among the known revocation approaches, verifier-local revocation (VLR) seems to be the most flexible one, because it only requires the verifiers to possess some up-to-date revocation information, but not the signers. All of the contemporary VLR group signatures operate in the bilinear map setting, and all of them will be insecure once quantum computers become a reality. In this work, we introduce the first lattice-based VLR group signature, and thus, the first such scheme that is believed to be quantum-resistant. In comparison with existing lattice-based group signatures, our scheme has several noticeable advantages: support of membership revocation, logarithmic-size signatures, and milder hardness assumptions. Moreover, our construction works without relying on public-key encryption schemes, which is an intriguing feature for group signatures.

Efficient VLR group signatures for smart cards

Group signatures are signature schemes which reveal only the group membership information of the signer. Verifier local revocation group signatures are group signatures which do not require the signer to update his secret key in order to provide revocation in the group. In this paper, we design a practical verifier local revocation group signature based on bilinear maps. Our scheme is the first VLR group signature using pairings which does not require expensive operations done by a signer, like exponentiation in the target group or pairing evaluation. This makes our signature scheme especially suitable for implementation on devices with restricted resources like smart cards.

SECURED DATA STORAGE AND AUDITING OF DATA INTEGRITY OVER DYNAMIC DATA IN CLOUD

Cloud computing is an emerging technology which supports the storage of data via internet. The process of communication is done in an open-access environment and this in turn creates some security and privacy issues which is a real challenge for the cloud users. This facility shoots up the necessity of secure data auditing mechanism over outsourced data. Most of the existing schemes lack the security feature, which can withstand collusion attacks between the cloud server and the unauthorised users. Another most important problem in existing system is data integrity. This paper presents a technique to overthrow the collusion attacks and the data auditing mechanism is achieved by means of vector commitment and backward unlinkable verifier local revocation group signature. The proposed work involves double encryption technique to deal with the privacy measures in cloud server. To extend the security measures a single file has been split into different blocks and stored with different file names. These may leads to the ambiguity for the attackers to trace out the original data. The performance of the proposed work is analysed and compared with the existing techniques and the experimental results are observed to be satisfactory in terms of computational and time complexity.

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.

Public Integrity Auditing for Shared Dynamic Cloud Data with Group User Revocation

The advent of the cloud computing makes storage outsourcing become a rising trend, which promotes the secure remote data auditing a hot topic that appeared in the research literature. Recently some research consider the problem of secure and efficient public data integrity auditing for shared dynamic data. However, these schemes are still not secure against the collusion of cloud storage server and revoked group users during user revocation in practical cloud storage system. In this paper, we figure out the collusion attack in the exiting scheme and provide an efficient public integrity auditing scheme with secure group user revocation based on vector commitment and verifier-local revocation group signature. We design a concrete scheme based on the our scheme definition. Our scheme supports the public checking and efficient user revocation and also some nice properties, such as confidently, efficiency, countability and traceability of secure group user revocation. Finally, the security and experimental analysis show that, compared with its relevant schemes our scheme is also secure and efficient.

Group User Revocation and Integrity Auditing of Shared Data in Cloud Environment

The enhancement of cloud computing make storage outsourcing becomes an exceeding trend, which result a secure data auditing a cool topic that emerge in research literature. Recently some researches consider the problem of efficient and secure public data authentication inspection for shared dynamic data. However, these schemes are still not secure against the collusion and leakage of cloud storage server from unauthorized attacker and revoked group users during user revocation in cloud storage system. In this paper, there will be auditing the integrity of shared data with dynamic groups in cloud. A new user can be added into the group and an existing group member can be revoked by preserving privacy including data backup based on vector commitment and verifier-local revocation group signature. This scheme supports the public validation and efficient user revocation and also some nice properties such as traceability, efficiency, confidently, countability. Finally, the security and experimental analysis show that our scheme is also secure and efficient.

More Efficient VLR Group Signature Based on DTDH Assumption

In VLR (verifier-local revocation) group signature, only verifiers are involved in the revocation of a member, while signers are not. Thus the VLR group signature schemes are suitable for mobile environments. To meet the requirement of speediness, reducing computation costs and shortening signature length are two requirements at the current research of VLR group signatures. A new VLR group signature is proposed based on q-SDH assumption and DTDH assumption. Compared with the existing VLR group signatures based on DTDH assumption, the proposed scheme not only has the shortest signature size, but also has the lowest computation costs , and can be applicable to mobile environments such as IEEE 802.1x. DOI: http://dx.doi.org/10.11591/telkomnika.v10i6.1428 Full Text: PDF

Privacy‐preserving registration protocol for mobile network

SUMMARYIn this paper, we propose a novel privacy‐preserving registration protocol that combines the verifier local revocation group signature with mobile IP. The protocol could achieve strong security guarantee, such as user anonymity via a robust temporary identity, local user revocation with untraceability support, and secure key establishment against home server and eavesdroppers. Various kinds of adversary attacks can be prevented by the proposed protocol, especially that deposit‐case attack does not work here. Meanwhile, a concurrent mechanism and a dynamical revocation method are designed to minimize the handover authentication delay and the home registration signals. The theoretical analysis and simulation results show that the proposed scheme could provide high security level besides lightweight computational cost and efficient communication performance. For instance, compared with Yang's scheme, the proposed protocol could decrease the falling speed of handover authentication delay up to about 40% with privacy being preserved. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Improved VLR Group Signature Based on DTDH Assumption

In VLR (verifier-local revocation) group signatures, revocation messages are only sent to signature verifiers (as opposed to both signers and verifiers). Consequently there is no need to contact individual signers when some user is revoked. Since signers have no load, the VLR group signature schemes are suitable for mobile environments. To meet the requirement of speediness in mobile communication, reducing computation costs and shortening signature length are two requirements at the current research of VLR group signatures. Based on this idea, an improved version of Zhou’s VLR group signature is given. Compared with the original scheme, the improved scheme not only can achieve the same security level, but also has shorter signature size and lower computation costs.

VLR group signatures with indisputable exculpability and efficient revocation

Group signatures (GSs) have been studied for two decades and have wide applications. In 2004, Boneh and Shacham formalised the concept of a GS scheme with verifier-local revocation (VLR), where a revocation list is distributed only to verifiers and signers who are not involved in the revocation process. Most of the existing VLR GS schemes do not satisfy exculpability (i.e., neither group members nor group issuers can produce signatures on behalf of other members) without fully trusted issuers or largely increased cost. In this paper, we propose a modification to this GS definition by adding a dispute process that can achieve exculpability with a low cost. We propose a concrete scheme under this new definition. Our scheme is more efficient than previous ones, both with and without exculpability. We also turn this scheme into a conventional VLR GS scheme supporting exculpability, which trade-off the dispute process with less efficient verification/opening processes.

Backward Unlinkability and Verifier-Local Revocation Group Signature Scheme with Lower Cost

In the current group signature schemes with backward unlinkability and verifier-local revocation (BU-VLR), the size of the public key is linear with the total number of time intervals, and the size of the revocation list (RL) is linear with the total number of time intervals and revoked members. Therefore, the cost is high not only in memory space but also in revocation token computation and revocation check. This paper proposes a BU-VLR group signature scheme under the DTDH assumption and the q-SDH assumption, which has short public key and RL to reduce the overheads in previous schemes. Moreover, it also has shorter signature length and smaller computation in signing.

More Efficient VLR Group Signature Satisfying Exculpability

In this letter, we improve NF'07 (Nakanishi and Funabiki) VLR group signature scheme such that it satisfies exculpability and has lower computation costs. In the proposed scheme, a group member generates his own private key together with the group manager in order to realize exculpability while the signature size is not made longer. Also, a new revocation check method is proposed at the step of verifying, and the computation costs of verifying are independent of the number of the revoked members, while they are linear with the number of the revoked members in the original scheme. Thus, the proposed scheme is more efficient than the original scheme and can be applicable to mobile environments such as IEEE 802.1x.

Verifier-Local Revocation Group Signature Schemes with Backward Unlinkability from Bilinear Maps

An approach of membership revocation in group signatures is verifier-local revocation (VLR for short). In this approach, only verifiers are involved in the revocation mechanism, while signers have no involvement. Thus, since signers have no load, this approach is suitable for mobile environments. Although Boneh and Shacham recently proposed a VLR group signature scheme from bilinear maps, this scheme does not satisfy the backward unlikability. The backward unlinkability means that even after a member is revoked, signatures produced by the member before the revocation remain anonymous. In this paper, we propose VLR group signature schemes with the backward unlinkability from bilinear maps.