149 research outputs found
New Parameters of Linear Codes Expressing Security Performance of Universal Secure Network Coding
The universal secure network coding presented by Silva et al. realizes secure
and reliable transmission of a secret message over any underlying network code,
by using maximum rank distance codes. Inspired by their result, this paper
considers the secure network coding based on arbitrary linear codes, and
investigates its security performance and error correction capability that are
guaranteed independently of the underlying network code. The security
performance and error correction capability are said to be universal when they
are independent of underlying network codes. This paper introduces new code
parameters, the relative dimension/intersection profile (RDIP) and the relative
generalized rank weight (RGRW) of linear codes. We reveal that the universal
security performance and universal error correction capability of secure
network coding are expressed in terms of the RDIP and RGRW of linear codes. The
security and error correction of existing schemes are also analyzed as
applications of the RDIP and RGRW.Comment: IEEEtran.cls, 8 pages, no figure. To appear in Proc. 50th Annual
Allerton Conference on Communication, Control, and Computing (Allerton 2012).
Version 2 added an exact expression of the universal error correction
capability in terms of the relative generalized rank weigh
Achievable rate region for three user discrete broadcast channel based on coset codes
We present an achievable rate region for the general three user discrete
memoryless broadcast channel, based on nested coset codes. We characterize
3-to-1 discrete broadcast channels, a class of broadcast channels for which the
best known coding technique\footnote{We henceforth refer to this as Marton's
coding for three user discrete broadcast channel.}, which is obtained by a
natural generalization of that proposed by Marton for the general two user
discrete broadcast channel, is strictly sub-optimal. In particular, we identify
a novel 3-to-1 discrete broadcast channel for which Marton's coding is
\textit{analytically} proved to be strictly suboptimal. We present achievable
rate regions for the general 3-to-1 discrete broadcast channels, based on
nested coset codes, that strictly enlarge Marton's rate region for the
aforementioned channel. We generalize this to present achievable rate region
for the general three user discrete broadcast channel. Combining together
Marton's coding and that proposed herein, we propose the best known coding
technique, for a general three user discrete broadcast channel.Comment: A non-additive 3-user discrete broadcast channel is identified for
which achievable rate region based on coset codes is analytically proven to
be strictly larger than that achievable using unstructured iid codes. This
version is submitted to IEEE Transactions on Information Theor
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
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
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