Practical Deniable Encryption

Abstract

A party using encrypted communication or storing data in an encrypted form might be forced to show the corresponding plaintext. It may happen for law enforcement reasons as well as for evil purposes. Deniable encryption scheme introduced by Canetti et al. shows that cryptography can be used against revealing information: the owner of the data may decrypt it in an alternative way to a harmless plaintext. Moreover, it is impossible to check if there is another hidden plaintext. The scheme of Canetti is inefficient in the sense that it is a special purpose scheme and using it indicates that there is some hidden message inside. We show that deniable encryption can be implemented in a different way so that it does not point to exploiting deniable encryption. Moreover, it is quite straightforward, so it can be used for both good and evil purposes. Apart from that we show that even the special purpose original scheme can be extended to allow, in some circumstances, any "depth" of deniability.