276 research outputs found
Steganographer Identification
Conventional steganalysis detects the presence of steganography within single
objects. In the real-world, we may face a complex scenario that one or some of
multiple users called actors are guilty of using steganography, which is
typically defined as the Steganographer Identification Problem (SIP). One might
use the conventional steganalysis algorithms to separate stego objects from
cover objects and then identify the guilty actors. However, the guilty actors
may be lost due to a number of false alarms. To deal with the SIP, most of the
state-of-the-arts use unsupervised learning based approaches. In their
solutions, each actor holds multiple digital objects, from which a set of
feature vectors can be extracted. The well-defined distances between these
feature sets are determined to measure the similarity between the corresponding
actors. By applying clustering or outlier detection, the most suspicious
actor(s) will be judged as the steganographer(s). Though the SIP needs further
study, the existing works have good ability to identify the steganographer(s)
when non-adaptive steganographic embedding was applied. In this chapter, we
will present foundational concepts and review advanced methodologies in SIP.
This chapter is self-contained and intended as a tutorial introducing the SIP
in the context of media steganography.Comment: A tutorial with 30 page
Deep Convolutional Neural Network to Detect J-UNIWARD
This paper presents an empirical study on applying convolutional neural
networks (CNNs) to detecting J-UNIWARD, one of the most secure JPEG
steganographic method. Experiments guiding the architectural design of the CNNs
have been conducted on the JPEG compressed BOSSBase containing 10,000 covers of
size 512x512. Results have verified that both the pooling method and the depth
of the CNNs are critical for performance. Results have also proved that a
20-layer CNN, in general, outperforms the most sophisticated feature-based
methods, but its advantage gradually diminishes on hard-to-detect cases. To
show that the performance generalizes to large-scale databases and to different
cover sizes, one experiment has been conducted on the CLS-LOC dataset of
ImageNet containing more than one million covers cropped to unified size of
256x256. The proposed 20-layer CNN has cut the error achieved by a CNN recently
proposed for large-scale JPEG steganalysis by 35%. Source code is available via
GitHub: https://github.com/GuanshuoXu/deep_cnn_jpeg_steganalysisComment: Accepted by IH&MMSec 2017. This is a personal cop
Side-Information For Steganography Design And Detection
Today, the most secure steganographic schemes for digital images embed secret messages while minimizing a distortion function that describes the local complexity of the content. Distortion functions are heuristically designed to predict the modeling error, or in other words, how difficult it would be to detect a single change to the original image in any given area. This dissertation investigates how both the design and detection of such content-adaptive schemes can be improved with the use of side-information.
We distinguish two types of side-information, public and private: Public side-information is available to the sender and at least in part also to anybody else who can observe the communication. Content complexity is a typical example of public side-information. While it is commonly used for steganography, it can also be used for detection. In this work, we propose a modification to the rich-model style feature sets in both spatial and JPEG domain to inform such feature sets of the content complexity.
Private side-information is available only to the sender. The previous use of private side-information in steganography was very successful but limited to steganography in JPEG images. Also, the constructions were based on heuristic with little theoretical foundations. This work tries to remedy this deficiency by introducing a scheme that generalizes the previous approach to an arbitrary domain. We also put forward a theoretical investigation of how to incorporate side-information based on a model of images. Third, we propose to use a novel type of side-information in the form of multiple exposures for JPEG steganography
Information-Theoretic Bounds for Steganography in Multimedia
Steganography in multimedia aims to embed secret data into an innocent
looking multimedia cover object. This embedding introduces some distortion to
the cover object and produces a corresponding stego object. The embedding
distortion is measured by a cost function that determines the detection
probability of the existence of the embedded secret data. A cost function
related to the maximum embedding rate is typically employed to evaluate a
steganographic system. In addition, the distribution of multimedia sources
follows the Gibbs distribution which is a complex statistical model that
restricts analysis. Thus, previous multimedia steganographic approaches either
assume a relaxed distribution or presume a proposition on the maximum embedding
rate and then try to prove it is correct. Conversely, this paper introduces an
analytic approach to determining the maximum embedding rate in multimedia cover
objects through a constrained optimization problem concerning the relationship
between the maximum embedding rate and the probability of detection by any
steganographic detector. The KL-divergence between the distributions for the
cover and stego objects is used as the cost function as it upper bounds the
performance of the optimal steganographic detector. An equivalence between the
Gibbs and correlated-multivariate-quantized-Gaussian distributions is
established to solve this optimization problem. The solution provides an
analytic form for the maximum embedding rate in terms of the WrightOmega
function. Moreover, it is proven that the maximum embedding rate is in
agreement with the commonly used Square Root Law (SRL) for steganography, but
the solution presented here is more accurate. Finally, the theoretical results
obtained are verified experimentally.Comment: arXiv admin note: substantial text overlap with arXiv:2111.0496
A Natural Steganography Embedding Scheme Dedicated to Color Sensors in the JPEG Domain
International audienceUsing Natural Steganography (NS), a cover raw image acquired at sensitivity ISO 1 is transformed into a stego image whose statistical distribution is similar to a cover image acquired at sensitivity ISO 2 > ISO 1. This paper proposes such an embedding scheme for color sensors in the JPEG domain, extending thus the prior art proposed for the pixel domain and the JPEG domain for monochrome sensors. We first show that color sensors generate strong intra-block and inter-block dependencies between DCT coefficients and that theses dependencies are due to the demosaicking step in the development process. Capturing theses dependencies using an empirical covariance matrix, we propose a pseudo-embedding algorithm on greyscale JPEG images which uses up to four sub-lattices and 64 lattices to embed information while preserving the estimated correlations among DCT coefficients. We then compute an approximation of the average embedding rate w.r.t. the JPEG quality factor and evaluate the empirical security of the proposed scheme for linear and non-linear demosaicing schemes. Our experiments show that we can achieve high capacity (around 2 bit per nzAC) with a high empirical security (P E 30% using DCTR at QF 95)
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