Paper 2009/578

Efficient and Provably Secure Certificateless Signcryption from Bilinear Maps

Wenjian Xie and Zhang Zhang

Abstract

Signcryption is a cryptographic primitive that fulfills both the functions of digital signature and public key encryption simultaneously, at a cost significantly lower than that required by the traditional signature-then-encryption approach. In 2008, Barbosa and Farshim introduced the notion of certificateless signcryption (CLSC) and proposed the first CLSC scheme [2], but which requires six pairing operations in the signcrypt and unsigncrypt phases. In this paper, aimed at designing an efficient CLSC scheme, we propose a new efficient CLSC scheme from bilinear maps, which requires only two pairing operations in the signcrypt and unsigncrypt phases and is more efficient than all the schemes available.

Note: Recently Sharmila Deva Selvi et al. pointed out that our scheme are not secure against Type I adversary [20]. We have to re-formalize a new security model which is a little weaker than the original one. In this model, we assume that the ciphertext from the signcryption oracle is valid under the original public key of the sender.