LDAC: A lightweight data access control scheme with constant size ciphertext in VSNs based on blockchain

The vehicular social network (VSN) offers diverse services such as traffic management, data sharing, and safe driving. However, malicious users in VSNs may steal and tamper with shared data, which can bring about privacy leakage issues and even cause serious traffic accidents. The CP-ABE algorithm can effectively protect shared data in VSNs and enable one-to-many data sharing. However, it faces issues of high computational complexity and high ciphertext storage overhead. To ensure the security and confidentiality of shared data in VSNs, we propose a lightweight data access control scheme(LDAC) with constant size ciphertext based on blockchain, which greatly reduces the storage and computing overhead of vehicle users. Due to the presence of malicious users and outdated attributes in VSNs, the LDAC scheme supports user revocation and attribute revocation. The multi-authority CP-ABE algorithm is combined with blockchain to enable distributed key distribution and the verification of decrypted data integrity. Security analysis indicates that the security and confidentiality of shared data can be effectively protected by the LDAC scheme. Experimental results indicate that the LDAC scheme can realize more lightweight calculation while achieving constant size ciphertext in comparison to the previous schemes.