An ID-based group-oriented decryption scheme secure against adaptive chosen-ciphertext attacks

ID-based decryption allows a sender to encrypt a message to an identity without access to a public key certificate. This paper proposes an ID-based group-oriented decryption scheme, secure against adaptive chosen-ciphertext attacks, which allows the sender to determine an access structure and generate a valid ciphertext on the chosen message. The correctness of decryption shares can be checked to detect when dishonest users in the access structure provide fake decryption shares. As a result, the message can be cooperatively recovered by users in the determined access structure. The formal proof of security of our scheme is based on the bilinear Diffie–Hellman problem in the random oracle model. Our proposed scheme is more efficient and provides higher security confidence than those in Li et al.’s certificate-based group-oriented decryption scheme.