Traceable ciphertext-policy attribute-based encryption scheme with attribute level user revocation for cloud storage.

Area of Science:

• Cryptography
• Information Security
• Computer Science

Background:

• Attribute-based encryption (ABE) schemes face challenges with key leakage and tracing malicious users.
• Sharing decryption keys among users with identical attributes complicates accountability in CP-ABE systems.
• Limited traceability and revocation mechanisms hinder commercial adoption of CP-ABE for secure cloud storage.

Purpose of the Study:

• To propose a novel traceable CP-ABE scheme with attribute-level user revocation for secure cloud storage.
• To address the limitations of key leakage and enhance accountability in CP-ABE systems.
• To enable fine-grained access control and resist collusion attacks.

Main Methods:

• Developed a traceable CP-ABE scheme (TUR-CPABE) incorporating attribute-level user revocation.
• Implemented secret key and ciphertext updates to counter collusion.
• Utilized outsourcing for encryption, decryption, and revocation to optimize computational load.
• Proved security against chosen plaintext attacks under the selective access policy based on the decisional q-BDHE assumption in the standard model.

Main Results:

• The proposed TUR-CPABE scheme effectively traces malicious users who leak key information.
• Attribute-level user revocation is supported, enabling fine-grained access control.
• The scheme demonstrates resilience against collusion attacks through key and ciphertext updates.
• Outsourced operations reduce the computational burden on data owners, users, and the trust authority.

Conclusions:

• The TUR-CPABE scheme provides a robust solution for secure cloud storage by enhancing traceability and user revocation.
• It facilitates fine-grained access control and mitigates risks associated with key sharing and malicious users.
• The scheme's security is formally proven, ensuring its reliability in real-world applications.