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Full-Text Articles in Information Security

On The Validity Of Digital Signatures, Jianying Zhou, Robert H. Deng Apr 2000

On The Validity Of Digital Signatures, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

An important feature of digital signatures is to serve as non-repudiation evidence. To be eligible as non-repudiation evidence, a digital signature on an electronic document should remain valid until its expiry date which is specified by some non-repudiation policy. As signature keys may be compromised and the validity of signatures may become questionable, additional security mechanisms need to be imposed on digital signatures. This paper examines the mechanisms for maintaining the validity of digital signatures, and provides a guideline on the use of these mechanisms in various context of applications.


Some Remarks On Fair Exchange Protocol, Jianying Zhou, Robert H. Deng, Feng Bao Jan 2000

Some Remarks On Fair Exchange Protocol, Jianying Zhou, Robert H. Deng, Feng Bao

Research Collection School Of Computing and Information Systems

Fair exchange turns out to be an increasingly important topic due to the rapid growth of electronic commerce. An exchange is deemed to be fair if at the end of exchange, either each party receives the expected item or neither party receives any useful information about the other’s item. Several protocols for fair exchange have been proposed in recent years. In this paper, we first examine a newly published fair exchange protocol and point out its flaws and weaknesses. We then put forward a more efficient and secure protocol and give an informal analysis.


A Signcryption Scheme With Signature Directly Verifiable By Public Key, Feng Bao, Robert H. Deng Feb 1998

A Signcryption Scheme With Signature Directly Verifiable By Public Key, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Signcryption, first proposed by Zheng, is a cryptographic primitive which combines both the functions of digital signature and public key encryption in a logical single step, and with a computational cost significantly lower than that needed by the traditional signature-then-encryption approach. In Zheng's scheme, the signature verification can be done either by the recipient directly (using his private key) or by engaging a zero-knowledge interative protocol with a third party, without disclosing recipient's private key. In this note, we modify Zheng's scheme so that the recipient's private key is no longer needed in signature verification. The computational cost of the …


A New On-Line Cash Check Scheme, Robert H. Deng, Yongfei Han, Albert B. Jeng, Teow-Hin Ngair Apr 1997

A New On-Line Cash Check Scheme, Robert H. Deng, Yongfei Han, Albert B. Jeng, Teow-Hin Ngair

Research Collection School Of Computing and Information Systems

This paper presents a new on-line cash check scheme which guarantees payor anonymity and improves upon existing similar schemes in efficiency and security.


An On-The-Fly Decoding Technique For Reed-Solomon Codes, Yuan Xing Lee, Robert H. Deng, Eng Hean Koh Sep 1996

An On-The-Fly Decoding Technique For Reed-Solomon Codes, Yuan Xing Lee, Robert H. Deng, Eng Hean Koh

Research Collection School Of Computing and Information Systems

An on-the-fly error correction technique for double-byte-error-correction (DBEC) and triple-byte-error-detection (TBED) Reed-Solomon (RS) codes is presented in this paper. This new algorithm finds number of byte-errors (single byte-error, double-byte errors, and triple-byte errors) by simply testing the values of a few syndrome functions, and locates and corrects the byte-errors directly without using the standard iterative algorithms for finding the error location polynomial. More importantly, it neither suffers from malfunctions incurred in Deng-Costello algorithm (1987), nor requires syndrome re-calculation as in Koksal-Yucel's modification (1992). It is also much more simpler and faster than the original Deng-Costello algorithm. It has found applications …


A Type I Hybrid Arq System With Adaptive Code Rates, Robert H. Deng, Michael L. Lin Feb 1995

A Type I Hybrid Arq System With Adaptive Code Rates, Robert H. Deng, Michael L. Lin

Research Collection School Of Computing and Information Systems

Type I hybrid ARQ systems use an error-control code of fixed rate for error-correction in each transmitted packet. In such systems, the code rate must be carefully chosen to match the channel bit error rate (BER) in order to maximize system throughput. Whenever there is a mismatch between code rate and channel BER, the throughput suffers. In this paper, we proposed a type I hybrid ARQ system which automatically adjusts its code rates to match channel BERs. The proposed system is very simple to implement and yet performs significantly better than type I hybrid ARQ systems of fixed code rate


Performance Of Combined Diversity Reception And Convolutional Coding For Qdpsk Land Mobile Radio, Huafei Zhou, Robert H. Deng, T. T. Tjhung Aug 1994

Performance Of Combined Diversity Reception And Convolutional Coding For Qdpsk Land Mobile Radio, Huafei Zhou, Robert H. Deng, T. T. Tjhung

Research Collection School Of Computing and Information Systems

Diversity reception and error correction coding are powerful techniques to combat multipath fading encountered in mobile radio communications. In order to improve the transmission performance of the ?/4-shift QDPSK signal in mobile radio channels, the authors propose a new scheme of combined coding and diversity reception, i.e., combination of diversity reception employing code combining (CC) and convolutional coding employing error-and erasure correction Viterbi decoding. They also consider another combination scheme, i.e., combination of diversity reception employing postdetection maximal ratio combining (MRC) and convolutional coding employing hard decision Viterbi decoding. They theoretically analyze the performance of the schemes taking into account …


On The Equivalence Of Mceliece's And Niederreiter's Public-Key Cryptosystems, Y. X. Li, Robert H. Deng, X. M. Wang Jan 1994

On The Equivalence Of Mceliece's And Niederreiter's Public-Key Cryptosystems, Y. X. Li, Robert H. Deng, X. M. Wang

Research Collection School Of Computing and Information Systems

It is shown that McEliece's and Niederreiter's public-key cryptosystems are equivalent when set up for corresponding choices of parameters. A security analysis for the two systems based on this equivalence observation, is presented


A Probabilistic Approach To Fault Diagnosis In Linear Lightwave Networks, Robert H. Deng, A. A. Lazar, W. Wang Dec 1993

A Probabilistic Approach To Fault Diagnosis In Linear Lightwave Networks, Robert H. Deng, A. A. Lazar, W. Wang

Research Collection School Of Computing and Information Systems

The application of probabilistic reasoning to fault diagnosis in linear lightwave networks (LLNs) is investigated. The LLN inference model is represented by a Bayesian network (or causal network). An inference algorithm is proposed that is capable of conducting fault diagnosis (inference) with incomplete evidence and on an interactive basis. Two belief updating algorithms are presented which are used by the inference algorithm for performing fault diagnosis. The first belief updating algorithm is a simplified version of the one proposed by Pearl (1988) for singly connected inference models. The second belief updating algorithm applies to multiply connected inference models and is …


An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou Nov 1993

An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou

Research Collection School Of Computing and Information Systems

The authors propose and study an adaptive error-control coding scheme for binary digital FM (BFM) mobile radio transmission. The scheme employs code combining through packet retransmissions. The number of transmissions of a packet is in proportion to the channel fading/noise levels, which is in contrast to time diversity techniques where a fixed number of repetitions of a data packet is performed even in the absence of channel errors. Furthermore, the receiver uses received signal envelopes as channel state information, which significantly improves the throughput and bit error rate (BER) performance. Performance of the proposed scheme is analyzed for frequency-flat Rayleigh …


Hybrid Arq Schemes For Point-To-Multipoint Communications Over Nonstationary Broadcast Channels, Robert H. Deng Sep 1993

Hybrid Arq Schemes For Point-To-Multipoint Communications Over Nonstationary Broadcast Channels, Robert H. Deng

Research Collection School Of Computing and Information Systems

Hybrid automatic-repeat-request (ARQ) error control schemes make use of both error detection and error correction in order to achieve high throughput and low undetected error probabilities on two way channels. Two hybrid ARQ schemes, termed hybrid go-back-N (HGB- N) and hybrid selective-repeat (HSR), are proposed for point-to-multipoint communications over broadcast channels. Both schemes incorporate a concatenated code for error correction and error detection. The performance study of the hybrid schemes is based on a two-state Markov model of a burst noise channel. An analytic solution is derived for the throughput efficiency of the HSR scheme, while approximations and computer simulation …


Performance Analysis Of Two Bridged Csma/Cd Networks, C. C. Ko, W. C. Wang, J. L. Du, Robert H. Deng, K. M. Lye Aug 1993

Performance Analysis Of Two Bridged Csma/Cd Networks, C. C. Ko, W. C. Wang, J. L. Du, Robert H. Deng, K. M. Lye

Research Collection School Of Computing and Information Systems

This paper analyses the performance of two non-persistent CSMA/CD LANs linked by a bridge. The main function of the bridge is to buffer all internet work packets and forward them across networks to their destinations. From establishing and solving the main equations governing the behaviour of the bridged networks, the effects of design parameters such as the bridge buffer size and re-transmission back off delay on the performance of the system are studied. It is shown that if these parameters are chosen properly, better throughput and delay performance can be obtained, when compared with an equivalent CSMA/CD network without using …


Performance Analysis Of Interconnected Lans With Server/Client Configuration, Jiangling Du, Robert H. Deng, Chi Chung Ko Jul 1993

Performance Analysis Of Interconnected Lans With Server/Client Configuration, Jiangling Du, Robert H. Deng, Chi Chung Ko

Research Collection School Of Computing and Information Systems

In this paper, we study the end-to-end performance of interconnected local area networks (LAN) with server/client configuration. The system uses bridges to connect two token-ring LANs through a high-speed communication link. A server station located on one LAN receives requests from client-stations on the same LAN as well as on the remote LAN, processes the requests, and returns responses to the client-stations. The end-to-end connections of the interconnected network are modelled as single-chain and multiple-chain closed queueing systems, which are solved by an iterative algorithm based on the MVA (mean value analysis) method. The performance examples are shown in terms …


Performance Of A Token-Passing System With Batch Arrivals And Its Application To File Transfers, Robert H. Deng, Xuanyu Zhang, Kuan Tase Huang Jul 1993

Performance Of A Token-Passing System With Batch Arrivals And Its Application To File Transfers, Robert H. Deng, Xuanyu Zhang, Kuan Tase Huang

Research Collection School Of Computing and Information Systems

This paper investigates the performance of token-passing systems with limited service and Poisson arrivals. For pure Poisson arrivals, the Laplace-Stieltjes Transform (LST) of an approximate customer/packet waiting time distribution is derived and expressed as a functional equation, from which the approximate mean and variance of waiting time are obtained; for batch Poisson arrivals, an approximate mean of waiting time is derived. Mean waiting time approximations are compared against both simulation results and other results presented in the literature; the variance approximation is evaluated by comparing it to simulation results only, since no other results on variance have been reported so …


Gateway Design For Lan Interconnection Via Isdn, Xian-Yu Zhang, Robert H. Deng Sep 1990

Gateway Design For Lan Interconnection Via Isdn, Xian-Yu Zhang, Robert H. Deng

Research Collection School Of Computing and Information Systems

Recently, the use of bridges/gateways to interconnect physically distant local area networks (LANs) has become increasingly popular. There are various ways of connecting these bridges/gateways. ISDN is one of them and an attractive one. In this paper we discuss our work in the gateway design for interconnecting LANs via ISDN.


Trellis-Coded Multidimensional Phase Modulation, S. S. Pietrobon, Robert H. Deng Jan 1990

Trellis-Coded Multidimensional Phase Modulation, S. S. Pietrobon, Robert H. Deng

Research Collection School Of Computing and Information Systems

A 2L-dimensional multiple phase-shift keyed (L×MPSK) signal set is obtained by forming the Cartesian product of L two-dimensional MPSK signal sets. A systematic approach to partitioning L×MPSK signal sets that is based on block coding is used. An encoder system approach is developed. It incorporates the design of a differential precoder, a systematic convolutional encoder, and a signal set mapper. Trellis-coded L×4PSK, L×8PSK, and L×16PSK modulation schemes are found for 1⩽L⩽4 and a variety of code rates and decoder complexities, many of which are fully transparent to discrete phase rotations of the signal set. The new codes achieve asymptotic coding …


High Rate Concatenated Coding Systems Using Multidimensional Bandwidth Efficient Inner Codes, Robert H. Deng, Daniel J. Jr. Costello Oct 1989

High Rate Concatenated Coding Systems Using Multidimensional Bandwidth Efficient Inner Codes, Robert H. Deng, Daniel J. Jr. Costello

Research Collection School Of Computing and Information Systems

A concatenated coding system using two-dimensional trellis-coded MPSK inner codes and Reed-Solomon outer codes for application in high-speed satellite communication systems was proposed previously by the authors (ibid., vol.37, no.5, p.420-7, May 1989). The authors extend their results to systems using symbol-oriented, multidimensional, trellis-coded MPSK inner codes. The concatenated coding systems are divided into two classes according to their achievable effective information rates. The first class uses multidimensional trellis-coded 8-PSK inner codes and achieves effective information rates around 1 b/dimension (spectral efficiency 2 b/s/Hz). The second class employs multidimensional trellis-coded 16-PSK inner codes and provides effective information rates around 1.5 …


Parity Retransmission Hybrid Arq Using Rate 1/2 Convolutional Codes On A Nonstationary Channel, L. R. Lugand, D. J. Costello, Jr., Robert H. Deng Jul 1989

Parity Retransmission Hybrid Arq Using Rate 1/2 Convolutional Codes On A Nonstationary Channel, L. R. Lugand, D. J. Costello, Jr., Robert H. Deng

Research Collection School Of Computing and Information Systems

A parity retransmission hybrid automatic repeat request (ARQ) scheme is proposed which uses rate 1/2 convolutional codes and Viterbi decoding. A protocol is described which is capable of achieving higher throughputs than previously proposed parity retransmission schemes. The performance analysis is based on a two-state Markov model of a nonstationary channel. This model constitutes a first approximation to a nonstationary channel. The two-state channel model is used to analyze the throughput and undetected error probability of the protocol presented when the receiver has both an infinite and a finite buffer size. It is shown that the throughput improves as the …


High Rate Concatenated Coding Systems Using Bandwidth Efficient Trellis Inner Codes, Robert H. Deng, D. J. Costello, Jr. May 1989

High Rate Concatenated Coding Systems Using Bandwidth Efficient Trellis Inner Codes, Robert H. Deng, D. J. Costello, Jr.

Research Collection School Of Computing and Information Systems

High-rate concatenated coding systems with bandwidth-efficient trellis inner codes and Reed-Solomon (RS) outer codes are investigated for application in high-speed satellite communication systems. Two concatenated coding schemes are proposed. In one the inner code is decoded with soft-decision Viterbi decoding, and the outer RS code performs error-correction-only decoding (decoding without side information). In the other the inner code is decoded with a modified Viterbi algorithm, which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, whereas branch metrics are used to provide reliability information on the decoded sequence. …


Dc-Free Coset Codes, Robert H. Deng, M. A. Herro Jul 1988

Dc-Free Coset Codes, Robert H. Deng, M. A. Herro

Research Collection School Of Computing and Information Systems

An upper bound on the bit-error probability (BEP) of a linear cyclic code over GF(2l) with hard-decision (HD) maximum-likelihood (ML) decoding on memoryless symmetric channels is derived. Performance results are presented for Reed-Solomon codes on GF(32), GF(64), and GF(128). Also, a union upper bound on the BEP of a linear cyclic code with either hard- or soft-decision ML decoding is developed, as well as the corresponding bounds for the extended code of a linear cyclic code. Using these bounds, which are tight at low bit error rate, the performance advantage of soft-decision (SD) ML and HD ML over bounded-distance (BD) …


Decoding Of Dbec-Tbed Reed-Solomon Codes, Robert H. Deng, Daniel J. Jr. Costello Nov 1987

Decoding Of Dbec-Tbed Reed-Solomon Codes, Robert H. Deng, Daniel J. Jr. Costello

Research Collection School Of Computing and Information Systems

A problem in designing semiconductor memories is to provide some measure of error control without requiring excessive coding overhead or decoding time. In LSI and VLSI technology, memories are often organized on a multiple bit (or byte) per chip basis. For example, some 256K bit DRAM's are organized in 32K ?? 8 bit-bytes. Byte-oriented codes such as Reed-Solomon (RS) codes can provide efficient low overhead error control for such memories. However, the standard iterative algorithm for decoding RS codes is too slow for these applications. In this correspondence we present a special decoding technique for double-byte-error-correcting (DBEC), triple-byte-error-detecting (TBED) RS …


Reliability And Throughput Analysis Of A Concatenated Coding System, Robert H. Deng, Daniel J. Costello Jul 1987

Reliability And Throughput Analysis Of A Concatenated Coding System, Robert H. Deng, Daniel J. Costello

Research Collection School Of Computing and Information Systems

The performance of a concatenated coding scheme for error control in ARQ systems is analyzed for both random error and burst-error channels. In particular, the probability of undetected error and the system throughput are calculated. In this scheme, the inner code is used for both error correction and error detection, and the outer code is used for error detection only. Interleaving/deinterleaving of the outer code is assumed. A retransmission is requested if either the inner code or the outer code detects the Presence of errors. Various coding examples are considered. The results show that concatenated coding can provide extremely high …