Paper 2018/106

On the Gold Standard for Security of Universal Steganography

Sebastian Berndt and Maciej Liśkiewicz


While symmetric-key steganography is quite well understood both in the information-theoretic and in the computational setting, many fundamental questions about its public-key counterpart resist persistent attempts to solve them. The computational model for public-key steganography was proposed by von Ahn and Hopper in EUROCRYPT 2004. At TCC 2005, Backes and Cachin gave the first universal public-key stegosystem - i.e. one that works on all channels - achieving security against replayable chosen-covertext attacks (SS-RCCA) and asked whether security against non-replayable chosen-covertext attacks (SS-CCA) is achievable. Later, Hopper (ICALP 2005) provided such a stegosystem for every efficiently sampleable channel, but did not achieve universality. He posed the question whether universality and SS-CCA-security can be achieved simultaneously. No progress on this question has been achieved since more than a decade. In our work we solve Hopper's problem in a somehow complete manner: As our main positive result we design an SS-CCA-secure stegosystem that works for every memoryless channel. On the other hand, we prove that this result is the best possible in the context of universal steganography. We provide a family of 0-memoryless channels - where the already sent documents have only marginal influence on the current distribution - and prove that no SS-CCA-secure steganography for this family exists in the standard non-look-ahead model.

Available format(s)
Publication info
A minor revision of an IACR publication in EUROCRYPT 2018
Eurocrypt 2018steganographypublic-key cryptography
Contact author(s)
sebastian berndt @ gmail com
2018-01-30: received
Short URL
Creative Commons Attribution


      author = {Sebastian Berndt and Maciej Liśkiewicz},
      title = {On the Gold Standard for Security of Universal Steganography},
      howpublished = {Cryptology ePrint Archive, Paper 2018/106},
      year = {2018},
      note = {\url{}},
      url = {}
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