Pairing-based public-key encryption schemes with backward-and-forward security

Identity-based cryptosystems utilize some arbitrary strings as the participants' public key in the underlying system. The encryptioner will not need to obtain the decryptioner's certificate. That will simplify the certificate managernent. Therefore, it is still interesting to propose some new identity-based encryption schemes. In this paper, we will propose two new different constructions, i.e. receiptor-oriented encryption schemes. They are both identity-based encryption schemes and also based on pairings. The proposed encryption schemes have a new advantage, i.e. backward-and-forward security. In addition, we provide the security analysis for the proposed schemes.