Secure Broadcasting of Two Encrypted Sources under Side-Channel Attacks

We consider the secure communication problem of broadcasting of two encrypted sources against an adversary which launches side-channel attacks. The adversary is not only allowed to eavesdrop the ciphertexts in the public communication channel but is also allowed to obtain the side information on the secret keys via the side-channel. In this paper, we propose a theoretical framework to solve this problem and also propose a countermeasure based on the post-encryption-compression paradigm. We provide an explicit sufficient condition to attain the exponential decay of the information leakage as the block lengths of encrypted sources become large.