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

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.