Abstract
Although a few unidirectional single-hop Identity-Based Proxy Re-Encryption (IBPRE) systems are available in the literature, none of them is CCA secure in the standard model. Besides, they can not support conditional re-encryption property, which allows a delegator to specify a condition for ciphertexts so that the proxy can re-encrypt ciphertexts only if the re-encryption key corresponding to the same condition is given. This paper, for the first time, proposes a new unidirectional single-hop Identity-Based Conditional Proxy Re-Encryption (IBCPRE) scheme that not only captures the property of IBPRE (i.e. identity-based re-encryption), but also supports conditional re-encryption. Moreover, the scheme can be proved secure against adaptive condition and adaptive identity chosen-ciphertext attacks in the standard model.