Decentralized and Collaborative Tracing for Group Signatures

Information Sciences, 2011

In an Optimistic Fair Exchange (OFE) for digital signatures, two parties exchange their signatures fairly without requiring any online trusted third party. The third party is only involved when a dispute occurs. In all the previous work, OFE has been considered only in a setting where both of the communicating parties are individuals. There is little work discussing about the fair exchange between two groups of users, though we can see that this is actually a common scenario in actual OFE applications. In this paper, we introduce a new variant of OFE, called Group-Oriented Optimistic Fair Exchange (GOFE). A GOFE allows two users from two different groups to exchange signatures on behalf of their groups in a fair and anonymous manner. Although GOFE may be considered as a fair exchange for group signatures, it might be inefficient if it is constructed generically from a group signature scheme. Instead, we show that GOFE is backward compatible to the Ambiguous OFE (AOFE). Also, we propose an efficient and concrete construction of GOFE, and prove its security under the security models we propose in this model. The security of the scheme relies on the decision linear assumption and strong Diffie-Hellman assumption under the random oracle model.

International Journal on Cybernetics & Informatics, 2016

Group Signature, extension of digital signature, allows members of a group to sign messages on behalf of the group, such that the resulting signature does not reveal the identity of the signer. The controllable linkability of group signatures enables an entity who has a linking key to find whether or not two group signatures were generated by the same signer, while preserving the anonymity. This functionality is very useful in many applications that require the linkability but still need the anonymity, such as sybil attack detection in a vehicular ad hoc network and privacy preserving data mining. This paper presents a new signature scheme supporting controllable linkability.The major advantage of this scheme is that the signature length is very short, even shorter than this in the best-known group signature scheme without supporting the linkability. A valid signer is able to create signatures that hide his or her identity as normal group signatures but can be anonymously linked regardless of changes to the membership status of the signer and without exposure of the history of the joining and revocation. From signatures, only linkage information can be disclosed, with a special linking key. Using this controllable linkability and the controllable anonymity of a group signature, anonymity may be flexibly or elaborately controlled according to a desired level.

Lecture Notes in Computer Science, 1997

. The concept of group signatures was introduced by Chaumet al. at Eurocrypt "91. It allows a member of a group to sign messagesanonymously on behalf of the group. In case of a later dispute adesignated group manager can revoke the anonymity and identify theoriginator of a signature. In this paper we propose a new efficient groupsignature scheme. Furthermore we

Lecture Notes in Computer Science, 2009

Traceable signature scheme extends a group signature scheme with an enhanced anonymity management mechanism. The group manager can compute a tracing trapdoor which enables anyone to test if a signature is signed by a given misbehaving user, while the only way to do so for group signatures requires revealing the signer of all signatures. Nevertheless, it is not tracing in a strict sense. For all existing schemes, T tracing agents need to recollect all N signatures ever produced and perform RN "checks" for R revoked users. This involves a high volume of transfer and computations. Increasing T increases the degree of parallelism for tracing but also the probability of "missing" some signatures in case some of the agents are dishonest. We propose a new and efficient way of tracing-the tracing trapdoor allows the reconstruction of tags such that each of them can uniquely identify a signature of a misbehaving user. Identifying N signatures out of the total of N signatures (N << N) just requires the agent to construct N small tags and send them to the signatures holder. N here gives a trade-off between the number of unlinkable signatures a member can produce and the efforts for the agents to trace the signatures. We present schemes with simple design borrowed from anonymous credential systems. Our schemes are proven secure respectively in the random oracle model and in the common reference string model (or in the standard model if there exists a trusted party for system parameters initialization).

Information

In modern applications, such as Electronic Voting, e-Health, e-Cash, there is a need that the validity of a signature should be verified by only one responsible person. This is opposite to the traditional digital signature scheme where anybody can verify a signature. There have been several solutions for this problem, the first one is we combine a signature scheme with an encryption scheme; the second one is to use the group signature; and the last one is to use the strong designated verifier signature scheme with the undeniable property. In this paper, we extend the traditional digital signature scheme to propose a new solution for the aforementioned problem. Our extension is in the sense that only a designated verifier (responsible person) can verify a signer’s signature, and if necessary (in case the signer refuses to admit his/her signature) the designated verifier without revealing his/her secret key is able to prove to anybody that the signer has actually generated the signatu...

International Journal of Information and Computer Security, 2008

In this paper, we describe a new cryptographic primitive called (One-Way) Signature Chaining. Signature chaining is essentially a method of generating a chain of signatures on the same message by different users. Each signature acts as a "link" of the chain. The one-way-ness implies that the chaining process is one-way in the sense that more links can be easily added to the chain. However, it is computationally infeasible to remove any intermediate links without removing all the links. The signatures so created are called chain signatures (CS). We give precise definitions of chain signatures and discuss some applications in trust transfer. We then present a practical construction of a CS scheme that is secure (in the random oracle model) under the Computational Diffie-Hellman (CDH) assumption in bilinear maps.

Lecture Notes in Computer Science, 2004

A group signature scheme allows a group member of a given group to sign messages on behalf of the group in an anonymous and unlinkable way. In case of a dispute, however, a designated group manager can reveal the signer of a valid group signature. Based on Song's forward-secure group signature schemes, Zhang, Wu, and Wang proposed a new group signature scheme with forward security at ICICS 2003. Their scheme is very efficient in both communication and computation aspects. Unfortunately, their scheme is insecure. In this paper we present a security analysis to show that their scheme is linkable, untraceable, and forgeable.

Computer Security – ESORICS 2016, 2016

This paper presents an anonymous certification (AC) scheme, built over an attribute based signature (ABS). After identifying properties and core building blocks of anonymous certification schemes, we identify ABS limitations to fulfill AC properties, and we propose a new system model along with a concrete mathematical construction based on standard assumptions and the random oracle model. Our solution has several advantages. First, it provides a data minimization cryptographic scheme, permitting the user to reveal only required information to any service provider. Second, it ensures unlinkability between the different authentication sessions, while preserving the anonymity of the user. Third, the derivation of certified attributes by the issuing authority relies on a non interactive protocol which provides an interesting communication overhead.

Internet Research, 2006

Purpose -To provide a cryptographic protocol for anonymously accessing services offered on the web. Such anonymous accesses can be disclosed or traced under certain conditions. Design/methodology/approach -The "traceable signature" scheme was used in conjunction with the "privilege management infrastructure". Findings -The cryptographic primitive provides a suitable tool for anonymous and unlinkable access to web resources based on the privileges that users hold. Moreover, the scheme allows for anonymity revocation and tracing of unlinkable accesses.

IEEE Transactions on Information Forensics and Security

Group data sharing in cloud environments has become a hot topic in recent decades. With the popularity of cloud computing, how to achieve secure and efficient data sharing in cloud environments is an urgent problem to be solved. In addition, how to achieve both anonymity and traceability is also a challenge in the cloud for data sharing. This paper focuses on enabling data sharing and storage for the same group in the cloud with high security and efficiency in an anonymous manner. By leveraging the key agreement and the group signature, a novel traceable group data sharing scheme is proposed to support anonymous multiple users in public clouds. On the one hand, group members can communicate anonymously with respect to the group signature, and the real identities of members can be traced if necessary. On the other hand, a common conference key is derived based on the key agreement to enable group members to share and store their data securely. Note that a symmetric balanced incomplete block design is utilized for key generation, which substantially reduces the burden on members to derive a common conference key. Both theoretical and experimental analyses demonstrate that the proposed scheme is secure and efficient for group data sharing in cloud computing.

2005

In this paper, we describe a new cryptographic primitive called (One-Way) Signature Chaining. Signature chaining is essentially a method of generating a chain of signatures on the same message by dierent users. Each signature acts as a &quot;link&quot; of the chain. The one-way-ness implies that the chaining process is one-way in the sense that more links can be easily added

Advances in Intelligent Systems and Computing, 2015

Group signature schemes allow a user to sign a message in an anonymous way on behalf of a group. In general, these schemes need the collaboration of a Key Generation Center or a Trusted Third Party, which can disclose the identity of the actual signer if necessary (for example, in order to settle a dispute). This paper presents the results obtained after implementing a group signature scheme using the Integer Factorization Problem and the Subgroup Discrete Logarithm Problem, which has allowed us to check the feasibility of the scheme when using big numbers.

2005

We provide a construction for a group signature scheme that is provably secure in a universally composable framework, within the standard model with trusted parameters. Our proposed scheme is fairly simple and its efficiency falls within small factors of the most efficient group signature schemes with provable security in any model (including random oracles). Security of our constructions require new cryptographic assumptions, namely the Strong LRSW, EDH, and Strong SXDH assumptions. Evidence for any assumption we introduce is provided by proving hardness in the generic group model.

Mathematics

Group signatures are a leading competing signature technique with a substantial amount of research. With group settings, group signatures provide user anonymity. Any group member with access to the group can generate a signature while remaining anonymous. The group manager, however, has the authority to expose and identify the signer if required. Since the privacy of the sender should be preserved, this is a conflict between privacy and accountability. Concerning high performance on security, we propose a novel, well-balanced security and privacy group signature scheme based on a general linear group over group ring. To the best of our knowledge, our work represents the first comprehensive framework for a group signature scheme that utilizes generic linear groups over group rings. We demonstrate that the competing security goals of message trustworthiness, privacy, and accountability are effectively resolved by our protocol. The results of the performance evaluation and simulation d...

IET Information Security, 2009

This paper introduces Hidden Identity-based Signatures (Hidden-IBS), a type of digital signatures that provide mediated signer-anonymity on top of Shamir's Identity-based signatures. The motivation of our new signature primitive is to resolve an important issue with the kind of anonymity offered by "group signatures" where it is required that either the group membership list is public or that the opening authority is dependent on the group manager for its operation. Contrary to this, Hidden-IBS do not require the maintenance of a group membership list and they enable an opening authority that is totally independent of the group manager. As we argue this makes Hidden-IBS much more attractive than group signatures for a number of applications. In this paper, we provide a formal model of Hidden-IBS as well as two efficient constructions that realize the new primitive. Our elliptic curve construction that is based on the SDH/DLDH assumptions produces signatures that are merely half a Kbyte long and can be implemented very efficiently.