Efficient secret authenticatable anonymous signcryption scheme with identity privacy

Three of the most important services offered by cryptography are confidential, private and authenticatability in distributed systems, such as P2P, trust negotiation and decentralized trust management. Information provider secretly encrypts a message with a hidden approach to protect message security and his privacy. Ring signcryption is an important way to realize full anonymity where the signcrypter cannot verify that this ciphertext was produced by himself. In this paper, we propose a novel construction of efficient secret authenticatable anonymous signeryption scheme in which only the actual signcrypter can authenticate that the ciphertext was produced by himself. The receiver cannot distinguish who the actual signcrypter is in the group even though he obtains all group members' private keys. Proposed scheme has the following properties: semantic security, signcrypter anonymity, signcrypter secret authenticatability, and unforgeability. We prove its security in the random oracle model under the DBDH assumption.