Secure certificateless proxy re-encryption without pairing

A Proxy Re-encryption (PRE) is a cryptographic scheme for delegation of decryption rights. In a PRE scheme, a semi-honest proxy agent of Bob re-encrypts the ciphertext, on the message intended for Alice, on behalf of Bob, without learning anything about the message. The PRE schemes are useful in the scenarios where data are desired to be shared with the authorized users over the cloud. For such important applications, in this paper, we present an efficient and secure proxy re-encryption scheme. To avoid the overhead due to certification and to get rid of the key escrow issue of identity-based setting, we construct our scheme on the certificateless setting. The scheme has been proved secure in random oracle model under the standard assumption, the hardness of the computational Diffie-Hellman problem (CDHP). Moreover, as we device a pairing-free construction, our scheme is significantly more efficient than the best available scheme.SCOPUS: cp.k