Optimized Ciphertext-Policy Attribute-Based Encryption with Efficient Revocation

In this work, we design a method for efficient revocation within Ciphertext-Policy Attribute-Based Encryption scheme.Our main technical innovation is based on linear secret sharing and binary tree techniques, every user in system is assigned with both a set of attributes and a unique identifier.Any user can also be efficiently revoked by using this identifier.Furthermore, this technique resulted in two key contributions: the size of the cryptographic key material is smaller and encryption/decryption cannot be affected with an unbounded number of revoked users.Then, the scheme is proved to be secure under the q-MEBDH assumption in the standard model.The efficiency is also optimized that the size of user's private key has only a constant increase.The revocation information is embedded in the ciphertext so that the fine-grained access control is more flexible.