Efficient and Provably Secure Certificateless Signcryption From Bilinear Maps

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 Certificate Less Sign Cryption (CLSC) and proposed the first CLSC scheme, but which requires six pairing operations in the signcrypt and unsigncrypt phases. In this paper, aimed at designing an efficient CLSC scheme, the authors pro-pose 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.