CP-ABE Key Delegation Scheme with Leakage Protection for Fog Computing

In fog computing, various connected devices of Internet-of-Things paradigm, share content with designated nearby fog devices for short term analytics. In this scenario, Ciphertext Policy-Attribute Based Encryption (CP-ABE) provides a secure content sharing mechanism by associating cryptographic secret keys with attributes assigned to each fog device by the system admin. For fail-safe transmission, if a fog device is about to become unavailable, it may need to delegate its keys to another device. Traditional CP-ABE supports key delegation but can't handle key leakage, leaving the whole system insecure and unstable. In this work, an efficient key delegation CP-ABE scheme with key leakage resistance has been proposed for fog computing. The scheme fully prevents key and protect unauthorised access. The results show that the proposed scheme is computationally efficient and secure. The encryption and decryption times are not increased by the proposed additional key leakage protection mechanism. Thus, the scheme enhances flexibility in content sharing in fog computing environment.