Abstract
Recently, proxy re-encryption (PRE) cryptosystem has been increasingly suggested in many fields, including the cloud and fog computing paradigm. In the PRE paradigm, in which the only confidentiality of security features of the transmitted message is guaranteed, the proxy entity can re-encrypt the message without exposing the corresponding plaintext. However, other security features such as integrity and authenticity are not guaranteed with using PRE cryptosystem. Thus, in a true assumption, the proxy entity is indicated as a semi-trusted entity, mostly in fog computing where fog nodes, such as the road side unit (RSU), are considered untrusted. The malicious RSU fog node can easily modify the integrity of the encrypted message. This paper proposes a proxy re-signcryption scheme with delegation property (PRSCD), in which the security features of data integrity, confidentiality, and authenticity are completely guaranteed during the transmission process. Thus, the PRSCD is proved in CCA on security models. An analysis of security illustrates that the PRSCD is able to prevent a malicious RSU fog node from performing a number of security challenges.