Fully Secure Identity Based Proxy Re-Encryption Schemes in the Standard Model

A proxy re-encryption scheme allows the proxy to transform ciphertext computed under one public key into the different ciphertext that can be decrypted by using another public key. Recently, many identity-based proxy re-encryption schemes have been proposed. However, all of these schemes are only proved secure in the random oracle not in the standard model. In this paper, Based on Waters´s identity based encryption, an identity based proxy re-encryption scheme is proposed that is proved fully secure without the random model. The proposed scheme´s security can be reduced to the decision Bilinear Diffie-Hellman assumption.