Revocation encryption scheme based on domestic cryptographic algorithm SM9

To address the limitations of lengthy system public keys and inefficient decryption in existing identity-based revocation encryption schemes, an optimized revocation encryption scheme was proposed based on SM9, China’s independently developed identity-based cryptographic algorithm. During encryption, a revoked user list was specified, ensuring that only non-revoked users could decrypt correctly. The scheme achieved constant ciphertext length and compact system public keys. For the “one-time encryption, multiple decryption” scenario, decryption efficiency was prioritized through bilinear map restructuring. Under the random oracle model, the scheme was proven to achieve chosen-plaintext security based on the GDDHE assumption. Theoretical analysis and experimental tests demonstrated that, compared with existing schemes, the system public key length was reduced by approximately 66.7% at the cost of a 50% expansion in key-encapsulated ciphertext length. When revoking 4 to 64 users, the decryption efficiency was improved by 65.0% to 85.2%. These results indicate that the scheme effectively enhances the practicality of SM9-based cryptographic systems in large-scale access control scenarios.