, Volume 27, Issue 1, pp 23-44

A One-Time Stegosystem and Applications to Efficient Covert Communication

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Abstract

We present the first information-theoretic steganographic protocol with an asymptotically optimal ratio of key length to message length that operates on arbitrary covertext distributions with constant min-entropy. Our results are also applicable to the computational setting: our stegosystem can be composed over a pseudorandom generator to send longer messages in a computationally secure fashion. In this respect our scheme offers a significant improvement in terms of the number of pseudorandom bits generated by the two parties in comparison to previous results known in the computational setting. Central to our approach for improving the overhead for general distributions is the use of combinatorial constructions that have been found to be useful in other contexts for derandomization: almost t-wise independent function families.

Communicated by Stefan Wolf
A. Kiayias is supported by NSF CAREER grant CCR-0447808 and NSF grants CNS-0831304, CNS-0831306.
This work was done while Y. Raekow was in the Department of Computer Science and Engineering, University of Connecticut.
A. Russell is supported by NSF CAREER grant CCR-0093065, and NSF grants CCR-0121277, CCR-0220264, CCR-0311368, and EIA-0218443.
This work was done while N. Shashidhar was in the Department of Computer Science and Engineering, University of Connecticut.