A traceable and revocable attribute-based encryption scheme with escrow-free in cloud storage

Abstract

Cloud storage not only saves the cost of local storage space but also facilitates data sharing. In the context of smart healthcare, electronic health records (EHR) are shared in plaintext across various healthcare systems. These systems also store EHR data in cloud servers, which makes it easy to leak user information and brings many security and privacy issues. In addition, malicious users might, for reasons such as personal gain, leak their keys through various means. Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is ideal for enabling detailed access control to cloud storage and protecting user data privacy. However, the extended CP-ABE has a key escrow problem, where some ciphertexts may be decrypted by authorities without user approval. To achieve privacy protection and effectively track malicious users, to revoke user access promptly, and to solve the key escrow challenge in smart healthcare systems, we introduce a privacy-preserving, traceable, revocable, key-escrow-free CP-ABE scheme. Ultimately, through security analysis, security proofs, and experimental results, we validate that the solution is both secure and effective.