Deniably Information-Hiding Encryptions Secure against Adaptive Chosen Ciphertext Attack

The deniably information-hiding encryption (DIHE) is a type of deniable encryption which can hide an additional information in encrypting a normal message. Even if the sender or the receiver is coerced to show the plaintext and the random coins in the encryption, a DIHE scheme behaves like only an innocent message is encrypted. Because it protects privacy against malicious coercer, the DIHE scheme is very useful in communication systems such as the cloud storage system when the communication channel is eavesdropped by a coercer. Previous DIHE schemes only concern the security under the adversary's chosen plaintext attack (CPA). This paper proposes the first DIHE construction with deniability and indistinguishability against adaptive chosen cipher text attack (CCA) which is stronger than the CPA attack. Our construction is simple and easy to implement. Furthermore, it achieves simultaneous sender and receiver deniability with negligible detection advantage.