A Secure Communication Model for Expressive Access Control Using CP-ABE

Attribute Based Encryption is a technique that associates user’s attributes with keys. Data is encrypted using a specific policy and only those keys whose attributes satisfy that policy are allowed to decrypt it. In this paper, we propose a secure communication model based on Ciphertext Policy Attribute Based Encryption (CP-ABE). This model allows Role Based Access Control for documents without the use of a secure server to enforce the access policies. We propose a scalable implementation for key revocation and user attribute updation with improved flexibility. Our method uses a key revoke-list and key-version to achieve this. We show the implementation using the CP-ABE toolkit, an open source library that implements the CP-ABE scheme. We also show how confidentiality, integrity and source authentication is achieved in our model.