An Identity-Based Ring Signcryption Scheme

Signcryption enables a user to perform digital signature for providing authenticity and public key encryption for providing message confidentiality simultaneously in a single logical step with a cost lesser than sign-thenencrypt approach. As the concept of ring signcryption emerged, various practical applications like electronic transaction protocol and key management protocols, felt the requirement of signer’s privacy, which was lacking in normal signcryption schemes. Without revealing the users’ identity of the ring signcryption can provide confidentiality and authenticity both. In this paper, we present a new ID-based ring signcryption scheme, motivated to the scheme provided by Zhu et al.[9]. Selvi et al. [17] and Wang et al. [23] found some security flaws in the Zhu’s scheme [9], which is being considered and repaired in this paper. The proposed scheme is proven to be secure against adaptive chosen ciphertext ring attacks (IND-IDRSC-CCA2) and secure against an existential forgery for adaptive chosen message attacks (EF-IDRSC-ACMA).