232 research outputs found
Constructing Perfect Steganographic Systems
We propose steganographic systems for the case when covertexts (containers)
are generated by a finite-memory source with possibly unknown statistics. The
probability distributions of covertexts with and without hidden information are
the same; this means that the proposed stegosystems are perfectly secure, i.e.
an observer cannot determine whether hidden information is being transmitted.
The speed of transmission of hidden information can be made arbitrary close to
the theoretical limit - the Shannon entropy of the source of covertexts. An
interesting feature of the suggested stegosystems is that they do not require
any (secret or public) key.
At the same time, we outline some principled computational limitations on
steganography. We show that there are such sources of covertexts, that any
stegosystem that has linear (in the length of the covertext) speed of
transmission of hidden text must have an exponential Kolmogorov complexity.
This shows, in particular, that some assumptions on the sources of covertext
are necessary
Perfectly Secure Steganography: Capacity, Error Exponents, and Code Constructions
An analysis of steganographic systems subject to the following perfect
undetectability condition is presented in this paper. Following embedding of
the message into the covertext, the resulting stegotext is required to have
exactly the same probability distribution as the covertext. Then no statistical
test can reliably detect the presence of the hidden message. We refer to such
steganographic schemes as perfectly secure. A few such schemes have been
proposed in recent literature, but they have vanishing rate. We prove that
communication performance can potentially be vastly improved; specifically, our
basic setup assumes independently and identically distributed (i.i.d.)
covertext, and we construct perfectly secure steganographic codes from public
watermarking codes using binning methods and randomized permutations of the
code. The permutation is a secret key shared between encoder and decoder. We
derive (positive) capacity and random-coding exponents for perfectly-secure
steganographic systems. The error exponents provide estimates of the code
length required to achieve a target low error probability. We address the
potential loss in communication performance due to the perfect-security
requirement. This loss is the same as the loss obtained under a weaker order-1
steganographic requirement that would just require matching of first-order
marginals of the covertext and stegotext distributions. Furthermore, no loss
occurs if the covertext distribution is uniform and the distortion metric is
cyclically symmetric; steganographic capacity is then achieved by randomized
linear codes. Our framework may also be useful for developing computationally
secure steganographic systems that have near-optimal communication performance.Comment: To appear in IEEE Trans. on Information Theory, June 2008; ignore
Version 2 as the file was corrupte
Product Perfect Codes and Steganography
A new coding technique to be used in steganography is evaluated. The performance
of this new technique is computed and comparisons with the well-known theoretical
upper bound, Hamming upper bound and basic LSB are established
Perfectly Secure Steganography: Capacity, Error Exponents, and Code Constructions
An analysis of steganographic systems subject to the following perfect
undetectability condition is presented in this paper. Following embedding of
the message into the covertext, the resulting stegotext is required to have
exactly the same probability distribution as the covertext. Then no statistical
test can reliably detect the presence of the hidden message. We refer to such
steganographic schemes as perfectly secure. A few such schemes have been
proposed in recent literature, but they have vanishing rate. We prove that
communication performance can potentially be vastly improved; specifically, our
basic setup assumes independently and identically distributed (i.i.d.)
covertext, and we construct perfectly secure steganographic codes from public
watermarking codes using binning methods and randomized permutations of the
code. The permutation is a secret key shared between encoder and decoder. We
derive (positive) capacity and random-coding exponents for perfectly-secure
steganographic systems. The error exponents provide estimates of the code
length required to achieve a target low error probability. We address the
potential loss in communication performance due to the perfect-security
requirement. This loss is the same as the loss obtained under a weaker order-1
steganographic requirement that would just require matching of first-order
marginals of the covertext and stegotext distributions. Furthermore, no loss
occurs if the covertext distribution is uniform and the distortion metric is
cyclically symmetric; steganographic capacity is then achieved by randomized
linear codes. Our framework may also be useful for developing computationally
secure steganographic systems that have near-optimal communication performance.Comment: To appear in IEEE Trans. on Information Theory, June 2008; ignore
Version 2 as the file was corrupte
Z2Z4-Additive Perdect Codes in Steganography
Steganography is an information hiding application which aims to
hide secret data imperceptibly into a cover object. In this paper, we describe a
novel coding method based on Z2Z4-additive codes in which data is embedded
by distorting each cover symbol by one unit at most (+-1-steganography). This
method is optimal and solves the problem encountered by the most e cient
methods known today, concerning the treatment of boundary values. The
performance of this new technique is compared with that of the mentioned
methods and with the well-known rate-distortion upper bound to conclude that
a higher payload can be obtained for a given distortion by using the proposed
method
StegBlocks: ensuring perfect undetectability of network steganography
The paper presents StegBlocks, which defines a new concept for performing
undetectable hidden communication. StegBlocks is a general approach for
constructing methods of network steganography. In StegBlocks, one has to
determine objects with defined properties which will be used to transfer hidden
messages. The objects are dependent on a specific network protocol (or
application) used as a carrier for a given network steganography method.
Moreover, the paper presents the approach to perfect undetectability of network
steganography, which was developed based on the rules of undetectability for
general steganography. The approach to undetectability of network steganography
was used to show the possibility of developing perfectly undetectable network
steganography methods using the StegBlocks concept.Comment: 6 pages, 1 figure, Accepted to Fourth International Workshop on Cyber
Crime (IWCC 2015), co-located with 10th International Conference on
Availability, Reliability and Security (ARES 2015), Toulouse, France, 24-28
August 201
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