3,271 research outputs found
Privacy-Preserving Distributed Optimization via Subspace Perturbation: A General Framework
As the modern world becomes increasingly digitized and interconnected,
distributed signal processing has proven to be effective in processing its
large volume of data. However, a main challenge limiting the broad use of
distributed signal processing techniques is the issue of privacy in handling
sensitive data. To address this privacy issue, we propose a novel yet general
subspace perturbation method for privacy-preserving distributed optimization,
which allows each node to obtain the desired solution while protecting its
private data. In particular, we show that the dual variables introduced in each
distributed optimizer will not converge in a certain subspace determined by the
graph topology. Additionally, the optimization variable is ensured to converge
to the desired solution, because it is orthogonal to this non-convergent
subspace. We therefore propose to insert noise in the non-convergent subspace
through the dual variable such that the private data are protected, and the
accuracy of the desired solution is completely unaffected. Moreover, the
proposed method is shown to be secure under two widely-used adversary models:
passive and eavesdropping. Furthermore, we consider several distributed
optimizers such as ADMM and PDMM to demonstrate the general applicability of
the proposed method. Finally, we test the performance through a set of
applications. Numerical tests indicate that the proposed method is superior to
existing methods in terms of several parameters like estimated accuracy,
privacy level, communication cost and convergence rate
Polar Coding for Secret-Key Generation
Practical implementations of secret-key generation are often based on
sequential strategies, which handle reliability and secrecy in two successive
steps, called reconciliation and privacy amplification. In this paper, we
propose an alternative approach based on polar codes that jointly deals with
reliability and secrecy. Specifically, we propose secret-key capacity-achieving
polar coding schemes for the following models: (i) the degraded binary
memoryless source (DBMS) model with rate-unlimited public communication, (ii)
the DBMS model with one-way rate-limited public communication, (iii) the 1-to-m
broadcast model and (iv) the Markov tree model with uniform marginals. For
models (i) and (ii) our coding schemes remain valid for non-degraded sources,
although they may not achieve the secret-key capacity. For models (i), (ii) and
(iii), our schemes rely on pre-shared secret seed of negligible rate; however,
we provide special cases of these models for which no seed is required.
Finally, we show an application of our results to secrecy and privacy for
biometric systems. We thus provide the first examples of low-complexity
secret-key capacity-achieving schemes that are able to handle vector
quantization for model (ii), or multiterminal communication for models (iii)
and (iv).Comment: 26 pages, 9 figures, accepted to IEEE Transactions on Information
Theory; parts of the results were presented at the 2013 IEEE Information
Theory Worksho
Polar Coding for Secure Transmission and Key Agreement
Wyner's work on wiretap channels and the recent works on information
theoretic security are based on random codes. Achieving information theoretical
security with practical coding schemes is of definite interest. In this note,
the attempt is to overcome this elusive task by employing the polar coding
technique of Ar{\i}kan. It is shown that polar codes achieve non-trivial
perfect secrecy rates for binary-input degraded wiretap channels while enjoying
their low encoding-decoding complexity. In the special case of symmetric main
and eavesdropper channels, this coding technique achieves the secrecy capacity.
Next, fading erasure wiretap channels are considered and a secret key agreement
scheme is proposed, which requires only the statistical knowledge of the
eavesdropper channel state information (CSI). The enabling factor is the
creation of advantage over Eve, by blindly using the proposed scheme over each
fading block, which is then exploited with privacy amplification techniques to
generate secret keys.Comment: Proceedings of the 21st Annual IEEE International Symposium on
Personal, Indoor, and Mobile Radio Communications (PIMRC 2010), Sept. 2010,
Istanbul, Turke
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