Anonymous encryption with partial-order subset delegation and its application in privacy email systems

In privacy-carrying email systems, the authors should guarantee that the email content is confidential and sometimes the sender/receiver identities are hidden. Also, they require that the key generation is flexible and manageable. In this study, first, they propose an anonymous encryption scheme that supports a partial-order subset delegatable ability. The proposed scheme achieves the security properties of confidentiality against adaptive chosen-plaintext attacks, anonymity against adaptive chosen-subset attacks and computational delegation indistinguishability. Secondly, they provide a deployment application of their anonymous encryption in an interdisciplinary group email management system with flexible and fine-grained key delegation. The deployment can achieve the privacy of message confidentiality, receiver anonymity and delegation obliviousness, which has fine-grained security in secure email systems. Finally, they provide an extension for the chosen-ciphertext secure scheme, and discuss the efficiency for decryption and the security level.