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Chinthani Uduwerelle

Bio: Chinthani Uduwerelle is an academic researcher from University of South Australia. The author has contributed to research in topics: Upper and lower bounds & Encryption. The author has an hindex of 3, co-authored 5 publications receiving 40 citations.

Papers
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Proceedings ArticleDOI
03 Oct 2011
TL;DR: In this article, a tradeoff between the effective key consumption and the number of channel uses for transmitting a ciphertext has been shown, and the existence of a fundamental tradeoff has been established.
Abstract: Shannon's fundamental bound for perfect secrecy says that the entropy of the secret message U cannot be larger than the entropy of the secret key R shared by the sender and the legitimate receiver. Massey gave an information theoretic proof of this result and the proof does not require U and R to be independent. By adding an extra assumption that I(U; R) = 0, we show a tighter lower bound on H(R) by proving that the logarithm of the message sample size cannot be larger than the entropy of the secret key. Then we consider that a perfect secrecy system is used multiple times. A new parameter, namely effective key consumption, is defined and justified. This paper shows the existence of a fundamental tradeoff between the effective key consumption and the number of channel uses for transmitting a ciphertext.

17 citations

Proceedings ArticleDOI
TL;DR: This paper shows the existence of a fundamental tradeoff between the effective key consumption and the number of channel uses for transmitting a ciphertext.
Abstract: Shannon's fundamental bound for perfect secrecy says that the entropy of the secret message cannot be larger than the entropy of the secret key initially shared by the sender and the legitimate receiver. Massey gave an information theoretic proof of this result, however this proof does not require independence of the key and ciphertext. By further assuming independence, we obtain a tighter lower bound, namely that the key entropy is not less than the logarithm of the message sample size in any cipher achieving perfect secrecy, even if the source distribution is fixed. The same bound also applies to the entropy of the ciphertext. The bounds still hold if the secret message has been compressed before encryption. This paper also illustrates that the lower bound only gives the minimum size of the pre-shared secret key. When a cipher system is used multiple times, this is no longer a reasonable measure for the portion of key consumed in each round. Instead, this paper proposes and justifies a new measure for key consumption rate. The existence of a fundamental tradeoff between the expected key consumption and the number of channel uses for conveying a ciphertext is shown. Optimal and nearly optimal secure codes are designed.

15 citations

Proceedings ArticleDOI
01 Jul 2012
TL;DR: This paper investigates how to design an error-free and perfectly secure crypto-system and introduces an approach based on prefix codes where the key consumption is minimum for fixed number of channel uses and an optimum partition code is introduced.
Abstract: We investigate how to design an error-free and perfectly secure crypto-system. In particular, we are interested in the efficiency of an EPS system. A approach based on prefix codes is introduced. Also an optimum partition code is introduced where the key consumption is minimum for fixed number of channel uses. Results obtained in this paper can also be applied to study the tradeoff between the key consumption and the number of channel uses needed to transmit the encrypted message.

8 citations

Proceedings ArticleDOI
09 Mar 2012
TL;DR: The behaviour of a crypto-system in a situation where an encoder PX'R'|U' is used to encrypt a source U which may be different from the source U' considered to design the encoder is studied.
Abstract: This paper studies the behaviour of a crypto-system in a situation where an encoder P X′R′|U′ is used to encrypt a source U which may be different from the source U′ considered to design the encoder. The original crypto-system is designed to achieve perfect secrecy under P U′ . The resulting system also achieves perfect secrecy regardless of the source distribution. Finally the mismatch in the system resources are calculated when the actual source distribution is known. The number of channel uses remains unchanged at the value for which the system is designed. Upper and lower bounds for the expected key consumption are derived.

1 citations

Proceedings ArticleDOI
07 Jul 2013
TL;DR: This paper provides an inequality which is a counterpart of the Kraft inequality in Error free Perfect Secrecy (EPS) system and illustrates some necessary and sufficient conditions for an EPS system to achieve the minimal expected key consumption.
Abstract: It is a well known result that the Kraft inequality is a necessary and sufficient condition for the existence of a uniquely decodable code. This paper provides an inequality which is a counterpart of the Kraft inequality in Error free Perfect Secrecy (EPS) system. Our inequality is a necessary and sufficient condition for the existence of an EPS system. It also illustrates some necessary and sufficient conditions for an EPS system to achieve the minimal expected key consumption.

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Journal ArticleDOI
16 Sep 2015
TL;DR: A special class of practical schemes for information-theoretic security that are based on 2-universal hash families based on secret key agreement and wiretap coding are reviewed, and general themes are identified.
Abstract: The information-theoretic approach to security entails harnessing the correlated randomness available in nature to establish security. It uses tools from information theory and coding and yields provable security, even against an adversary with unbounded computational power. However, the feasibility of this approach in practice depends on the development of efficiently implementable schemes. In this paper, we review a special class of practical schemes for information-theoretic security that are based on 2-universal hash families. Specific cases of secret key agreement and wiretap coding are considered, and general themes are identified. The scheme presented for wiretap coding is modular and can be implemented easily by including an extra preprocessing layer over the existing transmission codes.

40 citations

Journal ArticleDOI
01 Jan 2017
TL;DR: The mathematical framework for the analysis of visible light positioning systems is built, which can provide a provable and secure wireless communication capability and a novel authentication system based on users' locations.
Abstract: Lighting systems are undergoing a revolution from fluorescent lamps or tubes to light emitting diodes that offer greater energy efficiency and a longer lifetime. This paper considers using these light sources to provide other benefits. The proposed system has low deployment cost and most importantly, it uses the unique characteristics of visible light to complement existing wireless communication systems. This paper outlines a system design with three features. First, it can provide a provable and secure wireless communication capability. In particular, a user is authenticated according to his or her location. Second, it includes indoor positioning systems with high precision. Finally, it also supports information broadcast with a high frequency reuse factor. This paper provides both experimental and theoretical results. We build the mathematical framework for the analysis of visible light positioning systems. Experimental results and analysis are given to explain the concerns of light sensors in a mobile phone for building an indoor positioning system. A novel authentication system based on users' locations is proposed. Copyright © 2015 John Wiley & Sons, Ltd.

21 citations

Proceedings ArticleDOI
01 Jul 2012
TL;DR: An achievable rate tuple is defined in terms of the message, the key and the wiretapper's equivocation, and a tight rate region of the rate tuples is proved.
Abstract: In a point-to-point communication system which consists of a sender s, a receiver t and a set of noiseless channels, the senders wants to transmit a private message to the receiver t through the channels which may be eavesdropped by a wiretapper. The wiretapper can access any one but not more than one set of channels, which is referred to as a wiretap set. It is assumed that from each wiretap set, the wiretapper can obtain some partial information about the private message which is measured by the wiretapper's equivocation. The security strategy is to encode the message with some random key. Under these settings, we define an achievable rate tuple in terms of the message, the key and the wiretapper's equivocation, and prove a tight rate region of the rate tuples.

15 citations

Proceedings ArticleDOI
01 Jun 2020
TL;DR: There are significant differences in secret key/secrecy tradeoffs between lossless and almost-lossless compression under perfect secrecy, secrecy by design, maximal leakage, and local differential privacy.
Abstract: The relationship between secrecy, compression rate, and shared secret key rate is surveyed under perfect secrecy, equivocation, maximal leakage, local differential privacy, and secrecy by design. It is emphasized that the utility cost of jointly compressing and securing data is very sensitive to (a) the adopted secrecy metric and (b) the specifics of the compression setting. That is, although it is well-known that the fundamental limits of traditional lossless variable-length compression and almost-lossless fixed-length compression are intimately related, this relationship collapses for many secrecy measures. The asymptotic fundamental limit of almost-lossless fixed length compression remains entropy for all secrecy measures studied. However, the fundamental limits of lossless variable-length compression are no longer entropy under perfect secrecy, secrecy by design, and sometimes under local differential privacy. Moreover, there are significant differences in secret key/secrecy tradeoffs between lossless and almost-lossless compression under perfect secrecy, secrecy by design, maximal leakage, and local differential privacy.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the combination between causal/zero-delay source coding and information-theoretic secrecy and derived bounds on the key rate and coding rate needed for perfect zero-delay secrecy.
Abstract: We investigate the combination between causal/zero-delay source coding and information-theoretic secrecy. Two source coding models with secrecy constraints are considered. We start by considering zero-delay perfectly secret lossless transmission of a memoryless source. We derive bounds on the key rate and coding rate needed for perfect zero-delay secrecy. In this setting, we consider two models that differ by the ability of the eavesdropper to parse the bit-stream passing from the encoder to the legitimate decoder into separate messages. We also consider causal source coding with a fidelity criterion and side information at the decoder and the eavesdropper. Unlike the zero-delay setting where variable-length coding is traditionally used but might leak information on the source through the length of the codewords, in this setting, since delay is allowed, block coding is possible. We show that in this setting, a separation of encryption and causal source coding is optimal.

12 citations