Efficient and Generalized 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.

Lecture Notes in Computer Science, 2013

In a group signature scheme, group members are able to sign on behalf of the group. Since the introduction of this cryptographic authentication mechanism, several schemes have been proposed but only few of them enjoy a security in the standard model. Moreover, those provided in the standard model suffer the recourse to non standard-assumptions, or the expensive cost and bandwidth of the resulting signature. We provide three practical group signature schemes that are provably secure in the standard model under standard assumptions. The three schemes permit dynamic enrollment of new members while keeping a constant size for both keys and group signatures, and they improve the state-of-the art by several orders of magnitude.

Lecture Notes in Computer Science, 2010

Group signatures allow group members to anonymously sign messages in the name of a group such that only a dedicated opening authority can reveal the exact signer behind a signature. In many of the target applications, for example in sensor networks or in vehicular communication networks, bandwidth and computation time are scarce resources and many of the existent constructions simply cannot be used. Moreover, some of the most efficient schemes only guarantee anonymity as long as no signatures are opened, rendering the opening functionality virtually useless. In this paper, we propose a group signature scheme with the shortest known signature size and favorably comparing computation time, whilst still offering a strong and practically relevant security level that guarantees secure opening of signatures, protection against a cheating authority, and support for dynamic groups. Our construction departs from the popular sign-and-encrypt-and-prove paradigm, which we identify as one source of inefficiency. In particular, our proposal does not use standard encryption and relies on re-randomizable signature schemes that hide the signed message so as to preserve the anonymity of signers. Security is proved in the random oracle model assuming the XDDH, LRSW and SDLP assumptions and the security of an underlying digital signature scheme. Finally, we demonstrate how our scheme yields a group signature scheme with verifier-local revocation.

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.

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...

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.

Proceedings of the 5th conference on Smart Card …, 2002

Group signature schemes allow a group member to sign messages on behalf of the group. Such signatures must be anonymous and unlinkable but, whenever needed, a designated group manager can reveal the identity of the signer. During the last decade group signatures have been playing an important role in cryptographic research; many solutions have been proposed and some of them are quite efficient, with constant size of signatures and keys ([1], [6], [7] and [15]). However, some problems still remain among which the large number of computations during the signature protocol and the difficulty to achieve coalition-resistance and to deal with member revocation. In this paper we investigate the use of a tamper-resistant device (typically a smart card) to efficiently solve those problems.

International journal of engineering research and technology, 2020

Multisignature threshold schemes combine the properties of threshold group-oriented signature schemes and Multisignature schemes to yield a signature scheme that allows more group members to collaboratively sign an

1999

Group signature schemes allow a group member to anonymously sign on group's behalf. Moreover, in case of anonymity misuse, a group authority can recover the issuer of a signature. This paper analyzes the security of two group signature schemes recently proposed by Tseng and Jan. We show that both schemes are universally forgeable, that is, anyone (not necessarily a group member) is able to produce a valid group signature on an arbitrary message, which cannot be traced by the group authority.

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 "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