A revocable storage CP-ABE scheme with constant ciphertext length in cloud storage.

Area of Science:

• Cryptography
• Cloud Computing Security
• Information Security

Background:

• Ciphertext Policy Attribute-Based Encryption (CP-ABE) is crucial for secure data sharing and fine-grained access control in cloud storage.
• Existing CP-ABE schemes suffer from issues like increasing ciphertext length with policy complexity, low computational efficiency, and lack of fine-grained revocation.
• These limitations hinder the practical application of CP-ABE in scalable cloud storage environments.

Purpose of the Study:

• To propose an efficient and practical CP-ABE scheme for cloud storage.
• To address the limitations of existing schemes, specifically ciphertext length, computational efficiency, and revocation capabilities.
• To achieve fine-grained revocable storage with a constant ciphertext length.

Main Methods:

• The proposed scheme integrates proxy re-encryption with CP-ABE.
• It utilizes the AND-gates on multi-valued attributes with wildcards (AND*m) flexible access strategy.
• Complex decryption operations are outsourced to a third-party server with verification to ensure correctness.

Main Results:

• The scheme achieves revocable storage and maintains a constant ciphertext length, irrespective of access policy complexity.
• It enhances computational efficiency by outsourcing complex decryption tasks.
• Security is formally proven under the decisional bilinear Diffie-Hellman (DBDH) assumption.

Conclusions:

• The developed CP-ABE scheme offers an efficient and feasible solution for secure cloud storage.
• It effectively overcomes the drawbacks of traditional CP-ABE schemes regarding ciphertext size and revocation.
• The integration of proxy re-encryption and outsourced decryption provides a robust and practical approach to data security in the cloud.