To extend the proposed approach for supporting dynamic updates to access control policies in the integrated CP-ABE and Intel SGX solution, several strategies can be employed. First, a versioning system for access control policies can be implemented. Each time a policy is updated, a new version is created while retaining the previous versions for backward compatibility. This allows existing encrypted data to remain accessible under the old policies while new data can be encrypted with the updated policies.
Second, the use of a secure communication channel for policy updates is crucial. Remote attestation can be leveraged to ensure that only authorized entities can submit policy updates to the SGX enclave. This ensures that the integrity of the policy update process is maintained, preventing unauthorized modifications.
Additionally, the enclave can implement a mechanism to re-evaluate existing ciphertexts against the new policies. This can be achieved by storing the necessary metadata alongside the encrypted data, which includes the version of the policy used during encryption. When a user attempts to decrypt data, the enclave can check the policy version and apply the appropriate decryption logic based on the current policy state.
Lastly, to maintain security during policy updates, the enclave should ensure that sensitive information, such as the new policies, is sealed and only accessible within the enclave. This prevents exposure to potential attacks during the update process, thereby preserving the confidentiality and integrity of the access control policies.