Purified Authorization Service With Encrypted Message Moderation

Access control encryption enables access control on both senders and receivers, and enhances message sanitization compared with traditionally cryptographic access control mechanisms. However, it is usually built on top of encrypted messages, which makes it difficult to identify malicious data and amplifies abusive message transmission. Message franking and source tracing mechanisms facilitate a report of abusive messages while support only plain-data moderation in end-to-end encryption. In this work, we present sMAC, a purified access control framework which supports both sanitization and moderation over the encrypted messages. It enables security of the data privacy, sender anonymity and backward security. We instantiate it by proposing a cryptographic primitive named amenable ACE, which expands the message accountability algorithm module in addition to access control encryption. We give formal security proof of amenable ACE in the standard model. The experimental results show that amenable ACE is efficient where computational costs of textsf {Decrypt} , textsf {Stamp} , textsf {Verify} and textsf {Inspect} are independent of the message size.