Policy controlled system with anonymity

The revelation in April 2018 on Mark Zuckerberg's testimony to the congress raises the question about how much control people have over their data in the cloud. The big data privacy risks lead to the question of how to securely share the information among an assigned group or set of peoples. Furthermore, anonymity is an equally important issue in which the disclosed information should not be linked to the owner. The policy controlled signature and signcryption were presented in this paper to provide an affirmative answer to the aforementioned privacy issues. The primitives ensure the user's privacy, especially confidentiality and anonymity. Limiting only the permitted verifiers constricted by a verifier policy to validate a signature without revealing the identity of a signer, our policy controlled signature schemes provide both privacy and anonymity. An additional property of our policy controlled signcryption scheme provides not only privacy and anonymity, but also the confidentiality, where the information delivered to the receiver is encrypted and cannot be traced back to the sender's identity. Furthermore, our policy controlled signature scheme was proven to be secure against unforgeability and collision-resistant. Additionally, our policy controlled signcryption scheme was proven to be secure against indistinguishability and it is equivalent to a adaptive chosen ciphertext attack model of an encryption scheme, which is the strongest model in the existing literature.