An Efficient and Provably-Secure Identity-based Signcryption Scheme for Multiple PKGs

Abstract

In this paper, based on the scheme proposed by Barreto et al in ASIACRYPT 2005, an identity-based signcryption scheme in multiple Private Key Generator (PKG) environment is proposed, which mitigates the problems referred to users' private keys escrow and distribution in single PKG system. For security of the scheme, it is proved to satisfy the properties of message confidentiality and existential signature-unforgeability, assuming the intractability of the q-Strong Diffie-Hellman problem and the q-Bilinear Diffie-Hellman Inversion problem. For efficiency, compared with the state-of-the-art signcryption schemes of the same kind, our proposal needs less pairing computations and is shown to be the most efficient identity-based signcryption scheme for multiple PKGs up to date.