Public-Key Steganography with Active Attacks

A complexity-theoretic model for public-key steganography with active attacks is introduced. The notion of steganographic security against adaptive chosen-covertext attacks, abbreviated SS-CCA, is formalized and shown to be closely related to the notion of security against adaptive chosen-ciphertext attacks for public-key cryptosystems. In particular, it is shown that any SS-CCA stegosystem is a secure public-key cryptosystem and that an SS-CCA stegosystem can be realized from any secure public-key cryptosystem with almost uniform ciphertexts.