Anonymous signature scheme

In order to hide the identity of a signer, an anonymous signaure scheme is presented in this paper. In this scheme, a signer located in a specified group produces a signautre on behalf of the group. The recipient can verify whether the signature is valid and comes from the specified group, while tracing the signature to its source is impossible. The proposed anonymous signature is similarly to ring signature in some respects, for example, there is no manager, and no revocation mechanism against signer\u27s anonymity. The most different between these two kinds of signatures is that the group in ring signature is adaptively constructed by the signer, while the group in our scheme is fixed

An Efficient Code-Based Threshold Ring Signature Scheme with a Leader-Participant Model

Digital signature schemes with additional properties have broad applications, such as in protecting the identity of signers allowing a signer to anonymously sign a message in a group of signers (also known as a ring). While these number-theoretic problems are still secure at the time of this research, the situation could change with advances in quantum computing. There is a pressing need to design PKC schemes that are secure against quantum attacks. In this paper, we propose a novel code-based threshold ring signature scheme with a leader-participant model. A leader is appointed, who chooses some shared parameters for other signers to participate in the signing process. This leader-participant model enhances the performance because every participant including the leader could execute the decoding algorithm (as a part of signing process) upon receiving the shared parameters from the leader. The time complexity of our scheme is close to Courtois et al.’s (2001) scheme. The latter is often used as a basis to construct other types of code-based signature schemes. Moreover, as a threshold ring signature scheme, our scheme is as efficient as the normal code-based ring signature

Generalized Ring Signatures

Abstract-The concept of ring signature was first introduced b

Anonymous authentication mechanism based on group signature and pseudonym public key infrastructure for safety application of vechicular ad hoc network

Safety applications of Vehicular Ad hoc Network (VANET) demand delay intolerant and are vulnerable to attacks due to the mobility of nodes and wireless nature of their communications. These applications require an integrated security mechanism, which provides message integrity, anonymity, non-repudiation, revocation, availability, and location authentication services. This mechanism should provide acceptable message delay with or without dependency to Road Side Units (RSUs). Realizing the importance of VANET security, two mechanisms are proposed and evaluated in this research. The mechanisms are aimed at fulfilling the VANET security requirements for safety applications with acceptable message delay. Two new lightweight security mechanisms, RSU-Aided Anonymous Authentication (RAAA) and Group Signature-based Anonymous Authentication (GSAA) have been proposed. These mechanisms are based on Group Signature (GS) and Pseudonym Public Key Infrastructure (PPKI). GS scheme was applied to ensure anonymity, non-repudiation and revocation, whereas PPKI was applied to achieve authentication and message integrity. Additionally, a novel function for location verification was proposed to guarantee availability and location authentication. Simulations were performed using NS2 to verify and evaluate the efficiency of the mechanisms for urban and highway scenarios with various traffic conditions. Simulation results showed that RAAA and GSAA outperformed Group Signature and Identity-based Signature (GSIS), and Short-Term Linkable Group Signatures with Categorized Batch Verification (STLGSCBV). In comparison to GSIS and STLGSCBV, the results indicated improvements of at least 5.26% and 7.95% in terms of vehicle density impact on message delay, and at least 11.65% and 11.22% in the case of vehicle density impact on message loss ratio. Furthermore, the simulated RAAA and GSAA methods resulted in approximately 11.09% and 10.71% improvement in message delay during signature verification in comparison to GSIS and STLGSCBV. Additionally, RAAA and GSAA proved to achieve at least 13.44% enhancement by considering signature verification on message loss ratio in comparison to GSIS and 7.59% in comparison to STLGSCBV. The simulation results also demonstrated that less than 20ms message delay was achieved by RAAA and GSAA mechanisms in the case of less than 90 vehicles within the communication range. This is an acceptable message delay and hence, the proposed mechanisms have a great potential to be used in safety critical applications

(Hierarchical Identity-Based) Threshold Ring Signatures

We construct the first several efficient threshold ring signatures (TRS) without random oracles. Specializing to a threshold of one, they are the first several efficient ring signatures without random oracles after the only earlier instantiation of Chow, Liu, Wei, and Yuen. Further specializing to a ring of just one user, they are the short (ordinary) signatures without random oracles summarized in Wei and Yuen. We also construct the first hierarchical identity-based threshold ring signature without random oracles. The signature size is $O(n\lambda_s)$ bits, where $\lambda_s$ is the security parameter and $n$ is the number of users in the ring. Specializing to a threshold of one, it is the first hierarchical identity-based ring signature without random oracles. Further specializing to a ring of one user, it is the constant-size hierarchical identity-based signature (HIBS) without random oracles in Yuen-Wei - the signature size is $O(\lambda_s)$ bits which is independent of the number of levels in the hierarchy