Detecting Dangerous Queries: A New Approach for Chosen Ciphertext Security
The authors present a new approach for creating chosen ciphertext secure encryption. The focal point of their work is a new abstraction that they call Detectable Chosen Ciphertext Security (DCCA). Intuitively, this notion is meant to capture systems that are not necessarily Chosen Ciphertext Attack (CCA) secure, but where they can detect whether a certain query CT can be useful for decrypting (or distinguishing) a challenge ciphertext CT. They show how to build chosen ciphertext secure systems from DCCA security. They motivate their techniques by describing multiple examples of DCCA systems including creating them from 1-bit CCA secure encryption - capturing the recent Myers-shelat result (FOCS 2009). Their work identifies DCCA as a new target for building CCA secure systems.