33 research outputs found
Advances in Syndrome Coding based on Stochastic and Deterministic Matrices for Steganography
Steganographie ist die Kunst der vertraulichen Kommunikation. Anders als in der Kryptographie, wo der Austausch vertraulicher Daten für Dritte offensichtlich ist, werden die vertraulichen Daten in einem steganographischen System in andere, unauffällige Coverdaten (z.B. Bilder) eingebettet und so an den Empfänger übertragen.
Ziel eines steganographischen Algorithmus ist es, die Coverdaten nur geringfügig zu ändern, um deren statistische Merkmale zu erhalten, und möglichst in unauffälligen Teilen des Covers einzubetten. Um dieses Ziel zu erreichen, werden verschiedene Ansätze der so genannten minimum-embedding-impact Steganographie basierend auf Syndromkodierung vorgestellt. Es wird dabei zwischen Ansätzen basierend auf stochastischen und auf deterministischen Matrizen unterschieden. Anschließend werden die Algorithmen bewertet, um Vorteile der Anwendung von Syndromkodierung herauszustellen
Computing Dependencies between DCT Coefficients for Natural Steganography in JPEG Domain
International audienc
An Analysis of Perturbed Quantization Steganography in the Spatial Domain
Steganography is a form of secret communication in which a message is hidden into a harmless cover object, concealing the actual existence of the message. Due to the potential abuse by criminals and terrorists, much research has also gone into the field of steganalysis - the art of detecting and deciphering a hidden message. As many novel steganographic hiding algorithms become publicly known, researchers exploit these methods by finding statistical irregularities between clean digital images and images containing hidden data. This creates an on-going race between the two fields and requires constant countermeasures on the part of steganographers in order to maintain truly covert communication. This research effort extends upon previous work in perturbed quantization (PQ) steganography by examining its applicability to the spatial domain. Several different information-reducing transformations are implemented along with the PQ system to study their effect on the security of the system as well as their effect on the steganographic capacity of the system. Additionally, a new statistical attack is formulated for detecting ± 1 embedding techniques in color images. Results from performing state-of-the-art steganalysis reveal that the system is less detectable than comparable hiding methods. Grayscale images embedded with message payloads of 0.4bpp are detected only 9% more accurately than by random guessing, and color images embedded with payloads of 0.2bpp are successfully detected only 6% more reliably than by random guessing
Errorless Robust JPEG Steganography using Outputs of JPEG Coders
Robust steganography is a technique of hiding secret messages in images so
that the message can be recovered after additional image processing. One of the
most popular processing operations is JPEG recompression. Unfortunately, most
of today's steganographic methods addressing this issue only provide a
probabilistic guarantee of recovering the secret and are consequently not
errorless. That is unacceptable since even a single unexpected change can make
the whole message unreadable if it is encrypted. We propose to create a robust
set of DCT coefficients by inspecting their behavior during recompression,
which requires access to the targeted JPEG compressor. This is done by dividing
the DCT coefficients into 64 non-overlapping lattices because one embedding
change can potentially affect many other coefficients from the same DCT block
during recompression. The robustness is then combined with standard
steganographic costs creating a lattice embedding scheme robust against JPEG
recompression. Through experiments, we show that the size of the robust set and
the scheme's security depends on the ordering of lattices during embedding. We
verify the validity of the proposed method with three typical JPEG compressors
and benchmark its security for various embedding payloads, three different ways
of ordering the lattices, and a range of Quality Factors. Finally, this method
is errorless by construction, meaning the embedded message will always be
readable.Comment: 10 pages, 11 figures, 1 table, submitted to IEEE Transactions on
Dependable and Secure Computin