POSTER: Identity-based steganography and its applications to censorship resistance

The use of public-key steganography has been proposed for several censorship-resistance systems. However, distribution of the employed public keys presents an availability, scalability, and security challenge in many of these. To mitigate this problem, we introduce the notion of identity-based steganography. In particular, we define identity-based steganographic tagging (IBST), which allows a sender to produce a steganographic tag for a recipient's identity such that the tag can only be recognized by the intended recipient using her (identity-based) private key. We instantiate our definition by an efficient IBST scheme, provably secure under the bilinear decisional Diffie-Hellman assumption. We find IBST to be particularly useful when the censors are able to impede distribution of cryptographic keys or break forward security by compromising system agents. As two representative applications of IBST to censorship resistance systems, we first present an efficient and dynamic solution for the key distribution problem in Collage and second, we demonstrate that IBST can improve the scalability of Message in a Bottle.

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