Authenticated encryption and steganography in unconditional security setting

We address authenticated encryption, the cryptographic technique that simultaneously provides both confidentiality and authenticity, and steganography that hides the very existence of messages. We focus on tire security of these techniques against adversaries with unbounded computational sources. First, we reveal the strong security notion of uncondtionally secure authenticated encryption and show how to achieve it. Second, we study unconditionally secure stegosystems under active attacks and show how to construct them by the above mentioned unconditionally secure authenticated encryption schemes.