Exploring non-additive distortion in steganography

Conference item

Leading steganography systems make use of the Syndrome-Trellis Code (STC) algorithm to minimize a distortion function while encoding the desired payload, but this constrains the distortion function to be additive. The Gibbs Embedding algorithm works for a certain class of non-additive distortion functions, but has its own limitations and is highly complex. In this short paper we show that it is possible to modify the STC algorithm in a simple way, to minimize a non-additive distortion function suboptimally. We use it for two examples. First, applying it to the S-UNIWARD distortion function, we show that it does indeed reduce distortion, compared with minimizing the additive approximation currently used in image steganography, but that it makes the payload more – not less – detectable. This parallels research attempting to use Gibbs Embedding for the same task. Second, we apply it to distortion defined by the output of a specific detector, as a counter-move in the steganography game. However, unless the Warden is forced to move first (by fixing the detector) this is highly detectable.

Authors: Pevny, T; Ker, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Association for Computing Machinery
• Host title: IH&MMSec '18 Proceedings of the 6th ACM Workshop on Information Hiding and Multimedia Security
• Journal: 6th ACM Workshop on Information Hiding and Multimedia Security
• Pages: 109-114
• Publication date: 2018-06-14
• Acceptance date: 2018-03-29
• Event location: Innsbruck, Austria
• Event start date: 2018-06-20
• Event end date: 2018-06-22
• DOI: 10.1145/3206004.3206015
• ISBN: 9781450356251
• Keywords: Syndrome-Trellis Codes; distortion minimization; steganography