Browsing by Author "Yeh, YS"

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A fast algorithm for reliability-oriented task assignment in a distributed system
(2002-11-01)
Chiu, CC
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Yeh, YS
;
Chou, JS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
Distributed systems (DS) have become a major trend in computer systems design today because of their high speed and high reliability. Reliability is an important performance parameter in DS design. The distribution of programs and data files can affect the system reliability. Usually, designers add redundant copies of software and/or hardware to increase the system's reliability. The reliability-oriented task assignment problem, which is NP-hard, is to find a task distribution such that the program reliability or system reliability is maximized. In this paper, we developed a reliability-oriented task allocation scheme, based on a heuristic algorithm, for DS to find an approximate solution. The simulation shows that, in most test cases with one copy, the algorithm finds suboptimal solutions efficiently. When the algorithm cannot obtain an optimal solution, the deviation is very small; therefore, this is a desirable approach for solving these problems. (C) 2002 Elsevier Science B.V. All rights reserved.
A genetic algorithm for reliability-oriented task assignment with (k)over-tilde-$ duplications in distributed systems
(2006-03-01)
Chiu, CC
;
Hsu, CH
;
Yeh, YS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A distributed system is a collection of processor-memory pairs connected by communication links. The reliability of a distributed system can be expressed using the distributed program reliability, and distributed system reliability analysis. The computing reliability of a distributed system is an NP-hard problem. The distribution of programs & data-files can affect the system reliability. The reliability-oriented task assignment problem, which is NP-hard, is to find a task distribution such that the program reliability or system reliability is maximized. For example, efficient allocation of channels to the different cells can greatly improve the overall network throughput, in terms of the number of calls successfully supported. This paper presents a genetic algorithm-based reliability-oriented task assignment methodology (GAROTA) for computing the (k) over tilde -DTA reliability problem. The proposed algorithm uses a genetic algorithm to select a program & file assignment set that is maximal, or nearly maximal, with respect to system reliability. Our numerical results show that the proposed algorithm may obtain the exact solution in most cases, and the computation time seems to be significantly shorter than that needed for the exhaustive method. When the proposed method fails to give an exact solution, the deviation from the exact solution is very small. The technique presented in this paper would be helpful for readers to understand the correlation between task assignment reliability, and distributed system topology.
A genetic algorithm for the reliability optimization of a distributed system
(1998)
Chen, RS
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Chu, CC
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Yeh, YS
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
The widespread use of distributed system(DS) over the centralized systems can be attributed partially to its potential to enhance system reliability. In the reliability analysis of a DS, S-node Reliability(SNR) is defined as the probabilities that all nodes in S(a subset of all processing elements) are connected. SNR optimization for the distributed systems Exact Method(EM) has received only limited attention. Owing to the fact that computing reliability of DS is in general an NP-hard problem. Genetic Algorithms(GA) are search techniques for global optimization in a complex search space. GA can be applied to search a large, multimodel, complex problem spaces. Thus, there is a good potential to obtain optimal and near optimal results using GA for network reliability problem. In this work, we attempt to reduce computational time and complexity by presenting a method based on a Genetic Algorithm S-Node set Reliability Methodology (CASNR) to optimize a specified object function under a given capacity constraints. The versatility of genetic algorithm is illustrated by applying it to solve the S-node set reliability problem. Using GASNR to find the best S-node sets. Because the final number of best S-node sets is only one, we just take less time to compute the reliability using SYREL. In addition, the proposed algorithm is compared with the existing one for various topologies. Those results demonstrate that for a large DS, the proposed algorithm is more efficient in execution time.
A homophonic DES
(1998-06-30)
Hsieh, TM
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Yeh, YS
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Hsieh, YC
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Wang, CC
;
資訊科學與工程研究所
In this paper, we propose a variant of DES called a homophonic DES. The DES algorithm is strengthened by adding some random bits into the plaintext, which are placed in particular positions to maximize diffusion, and to resist differential attack. (C) 1998 Elsevier Science B.V. All rights reserved.
A probability model for reconstructing secret sharing under the internet environment
(1999-06-01)
Lee, CY
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Yeh, YS
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Chen, DJ
;
Ku, KL
;
資訊科學與工程研究所
Internet technologies have ushered in a new era for computer-related communications. Use of the Internet for commercial applications and resource sharing has accelerated in recent years as well. Owing to such developments, Internet security has become a critical issue for both academic and commercial sectors. Several studies have focused on areas involving network security such as authentication, privacy, and integrity. In some applications, an important message can be divided into pieces and allocated at several different sites over the Internet for security access concern. For example, an important map that can be used to access a military base, a vital key that can be used to give a military order or command. To access such an important message, one must reconstruct the divided pieces from different sites under the given Internet environment. In this paper, we present a novel probability model for reconstructing secret sharing under the Internet. Also, how to assign the divided shares into different sites over the Internet is studied. Also proposed herein are algorithms to perform shares assignment and to evaluate the probability of reconstructing the divided pieces into the original secret. Illustrative examples and simulation results demonstrate the feasibility of the proposed approach. (C) 1999 Elsevier Science Inc. All rights reserved.
A reversing traversal algorithm to predict deleting node for the optimal k-node set reliability with capacity constraint of distributed systems
(2001-02-15)
Yeh, YS
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Chiu, CC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A k-node set reliability with capacity constraint is defined as the probability that a set, K, of nodes is connected in a distributed system and the total capacity of the nodes in K is sufficient under a given capacity. This is generally an NP-hard problem. For reducing computational time, a reasonable k-node set within a given capacity constraint must be determined by an efficient algorithm. In this work, we propose a reversing traversal method to derive a k-node set under capacity constraint having an approximate solution. Initially, the set K is assigned to all the nodes in a system. The proposed algorithm uses an objective function to evaluate the fitness value of each node in K and predict a deleting node, which is not a critical node, in K with minimal fitness value. After deleting the node, the fitness value of each node that is adjacent to the deleted node is tuned. The above two processes are repeated until the total capacity of the nodes in each subset of the set K does not satisfy the capacity constraint. In our simulation, the proposed method can obtain an exact solution above 90%. When a sub-optimal solution is obtained, the average deviation from an exact solution is under 0.0033. Computational results demonstrate that the proposed algorithm is efficient in execution time and effective for obtaining an optimal k-node set with capacity constraint. (C) 2001 Elsevier Science B.V. All rights reserved.
A share assignment method to maximize the probability of secret sharing reconstruction under the Internet
(1998)
Lee, CY
;
Yeh, YS
;
Chen, DJ
;
Ku, KL
;
資訊科學與工程研究所
The use of Internet for various business applications and resource sharing has grown tremendously over the last few years. In some applications, an important document may be required to be divided into pieces and be allocated in different locations over the Internet for security access concern. For example, an important map that can be used to access a military base, an important key that can be used to give a military order or command. To access such an important document, one must reconstruct the divided pieces from different locations. In this paper, a probability model for reconstructing the secret sharing under the Internet is proposed. Also, how to assign the divided shares into different locations is studied. Particularly, algorithms to perform share assignment and to reconstruct the divided pieces into the original secret are proposed.
A share assignment method to maximize the probability of secret sharing reconstruction under the Internet
(2000-02-01)
Lee, CY
;
Yeh, YS
;
Chen, DJ
;
Ku, KL
;
資訊科學與工程研究所
The use of Internet for various business applications and resource sharing has grown tremendously over the last few years. Internet security has become an important issue for both academic and industrial sectors. Much related network security research has been conducted such as user authentication, data confidentiality, and data integrity. In some applications, a critical document can be divided into pieces and allocated in different locations over the Internet for security access concern. To access such an important document, one must reconstruct the divided pieces from different locations under the given Internet environment. In this paper, a probability model for reconstructing secret sharing and algorithms to perform share assignment are presented. Also, an evaluation algorithm to measure the probability of secret sharing reconstruction is proposed. Illustrative examples and simulation results are provided to demonstrate the applicability of our method.
An extended DES
(2002-05-01)
Yeh, YS
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Hsu, CH
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資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The original S-boxes and algorithms of DES are designed to resist differential attack[11]. We propose eight more new S-boxes with the same cryptographic properties as S-boxes in DES. These 16 S-boxes are used to construct the extended DES, which is double the size of the original DES. The differential and linear cryptanalyses of the extended DES are given. The complexities of the two attacks are found to be 2(112) and 2(142) respectively.
Analysis of Sun et al.'s linkability attack on some proxy blind signature schemes
(2006-02-01)
Wu, LC
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Yeh, YS
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Liu, TS
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資訊工程學系
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Department of Computer Science
The proxy blind signature scheme allows the designated proxy signer using the proxy secret key to generate a blind signature on behalf of the original signer. Tan et al. presented the DLP-based and ECDLP based blind signature schemes. Awasthi and Lal proposed a improved DLP-based scheme later. Recently, Sun et al. presented linkability attack on Tan et al.'s and Awasthi-Lal's proxy blind signature schemes respectively. In this paper, we show that Sun et al.'s attack is failed and these schemes are still satisfy the unlinkability property. (C) 2005 Elsevier Inc. All rights reserved.
Applying lightweight directory access protocol service on session certification authority
(2002-04-05)
Yeh, YS
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Lai, WS
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Cheng, CJ
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
Lightweight Directory Access Protocol (LDAP) service is a new technology being applied on the Internet. On large-scale network systems using Transmission control protocol (TCP)/Internet protocol (IP), there is no standard suggested for single directory-certainly without one to be routinely used on the scale of intranets. LDAP service has many great features, such as providing quick and advanced search, quick response and hierarchy view of data. It also can be utilized to many different applications. Certification Authority (CA) is a trusted system, and it plays an important role just like a notary bridging between end-entities and helps end-entities to establish a secure environment. If someone wants to trade or communicate with others, he or she needs the certificate issued by the CA to help him or her get the trust from others. When a number of end-entities need this service, the load of CA may become huge. Using distributed CAs may sound Eke a good idea, but it costs too much. In this paper, we have designed a Session CA using a directory system to share its load without the necessity to maintain the Certificate Revocation List (CRL) because the lifetime of the attribute certificate is very short. With these great features of LDAP service mentioned above, it becomes desirable that we can apply them to design a new CA system. By using LDAP service, we can reduce the load of certification significantly between CA and endentity. In addition, this new technology can reduce the maintenance work of administration and improve the efficiency of our new proposed CA. Furthermore, combining with Role-Based Access Control (RBAC) and attribute certificate, the security of our system is greatly improved. (C) 2001 Elsevier Science B.V. All rights reserved.
Broadcasting secrets in communication networks
(1998-03-01)
Chang, CC
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Wu, TC
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Yeh, YS
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資訊科學與工程研究所
;
Institute of Computer Science and Engineering
One property of a broadcast channel is that a single message broadcasted from an originator may be received simultaneously by several recipients in communication links. Based on the Chinese remainder theorem (CRT), we propose a new secure broadcasting scheme to distribute different secrets in one single broadcasting transaction such that each of the secrets is dedicated to different authorized recipients. On receiving the ciphertext broadcasted by the originator, only authorized recipients can obtain and authenticate their dedicated secrets individually, while no secret is revealed to unauthorized recipients. In a single broadcasting transaction, each authorized recipient cannot know who are the other intended recipients for this transaction. Furthermore, the processes for decryption and authentication of the dedicated secret are performed through simple arithmetic computation, i.e., modular operations, hence it is suitable for the applications that the recipient has less computing power. We also show that the proposed scheme can withstand the attack on replaying a previously intercepted broadcasting message.
Comment on traceability on RSA-based partially signature with low computation
(2005-11-15)
Wu, LC
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Yeh, YS
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資訊工程學系
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Department of Computer Science
Recently, Chien et al. proposed RSA-based partially blind signature with low computation for mobile and smart-card applications. Hwang et al. claimed that Chien et al.'s scheme cannot meet the untraceability property of the blind signature later. In this paper, we show that Hwang et al.'s claim is incorrect and Chien et al.'s scheme is still satisfy the untraceability property. (c) 2005 Elsevier Inc. All rights reserved.
Construct message authentication code with one-way hash functions and block ciphers
(1999-02-01)
Yeh, YS
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Wang, CC
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
We suggest an MAC scheme which combines a hash function and an block cipher in order. We strengthen this scheme to prevent the problem of leaking the intermediate hash value between the hash function and the block cipher by additional random bits. The requirements to the used hash function are loosely. Security of the proposed scheme is heavily dependent on the underlying block cipher. This scheme is efficient on software implementation for processing long messages and has clear security properties.
Date attachable electronic cash
(2000-02-15)
Fan, CI
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Chen, WK
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Yeh, YS
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資訊工程學系
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Department of Computer Science
In this paper we propose a new untraceable electronic cash scheme which makes it possible for a payer to attach the desired date to his electronic cash during a transaction. With the aid of the date attachability property, the date on which an electronic cash is deposited in the bank cannot be forged in an electronic cash scheme. It is conducive to the unforgeability of the number of days for which the cash has been stored in the bank for some necessary purposes such as interest calculation. Our scheme not only keeps the attached date from being forged but also avoids two or more different dates being attached to the same electronic cash. Furthermore, the date attachment does not affect the untraceability property of electronic cash. Comparing with typical electronic cash schemes, the extra computation required for date attachment is just hashing. (C) 2000 Elsevier Science B.V. All rights reserved.
Dynamic GOST
(2000-11-01)
Yeh, YS
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Lin, CH
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Wang, CC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
GOST is a block algorithm which was adopted as a standard by the former Soviet Union. Because it keeps a lot of secret information, including S-boxes, the algorithm is secure and easy to understand. In this article, we propose a variant of COST, called dynamic COST, in which permutations are applied. With the permutation information securely kept: the new version of COST is more secure and better to withstand differential and linear attacks.
Heteroleptic cyclometalated iridium(III) complexes displaying blue phosphorescence in solution and solid state at room temperature
(2005-10-31)
Yang, CH
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Li, SW
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Chi, Y
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Cheng, YM
;
Yeh, YS
A series of heteroleptic Ir(III) metal complexes 1-3 bearing two N-phenyl-substituted pyrazoles and one 2-pyridyl pyrazole (or triazole) ligands were synthesized and characterized to attain highly efficient, room-temperature blue phosphorescence. The N-phenylpyrazole ligands, dfpzH = 1-(2,4-difluorophenyl)pyrazole, fpzH = 1-(4-fluorophenyl)-pyrazole, dfmpzH = 1-(2,4-difluorophenyl)-3,5-dimethylpyrazole, and fmpzH = 1-(4-fluorophenyl)-3,5-dimethylpyrazole, show a similar reaction pattern with respect to the typical cyclometalated (C boolean AND N) chelate, which utilizes its orthosubstituted phenyl segment to link with the central Ir(III) atom, while the second 2-pyridylpyrazole (or triazole) ligand, namely, fppzH = 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, fptzH = 3-(trifluoromethyl)-5-(2-pyridyl)triazole, and hptzH = 3-(heptafluoropropyl)-5-(2-pyridyl)triazole, undergoes typical anionic (N boolean AND N) chelation to complete the octahedral framework. X-ray structural analyses on complexes [(dfPZ)(2)Ir(fppz)] (1a) and [(fMPZ)(2)Ir(hptz)] (3d) were established to confirm their molecular structures. Increases of the pi pi* energy gaps of the Ir(III) metal complexes were systematically achieved with two tuning strategies. One involves the substitution for one or two fluorine atoms at the N-phenyl segment or the introduction of two electron-releasing methyl substituents at the pyrazole segment of the H(CAN) ligands. Alternatively, we have applied the more electron-accepting triazolate in place of the pyrazolate segment for the third (N boolean AND N)H ligand, Our results, on the basis of steady-state, relaxation dynamics, and theoretical approaches, lead to a conclusion that, for complexes 1-3, the weakening of iridium metal-ligand bonding strength in the T-1 state plays a crucial role for the fast radiationless deactivation. For the case of [(fMPZ)(2)Ir(hptz)] (3d), a thermal deactivation barrier of 4.8 kcal/mol was further deduced via temperature-dependent studies. The results provide a theoretical basis for future design and synthesis of the corresponding analogues suited to blue phosphorescent emitters.
Improving Lamport one-time signature scheme
(2005-08-05)
Chang, MH
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Yeh, YS
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
One-time signature scheme, a kind of digital signature schemes, is used to sign at most one message; otherwise the signature can be forged. One of the advantages is that the one-time signature generation and verification are very efficient and it is useful for chip cards, where low computation complexity is required. Lamport first invented a one-time digital signature scheme based on one-way functions. However, the Lamport one-time scheme requires a large amount of space for storage of authentic information if a large number of messages are signed. In this paper, we improve the Lamport one-time signature on the amount of storage space for public keys and signed message saving storage space and propose an efficient scheme to sign a long message. Thus, we make the Lamport one-time signature useful in practice. (c) 2004 Elsevier Inc. All rights reserved.
Interplay between intra- and interligand charge transfer with variation of the axial N-heterocyclic ligand in osmium(II) pyridylpyrazolate complexes: Extensive color tuning by phosphorescent solvatochromism
(2005-10-21)
Li, SW
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Cheng, YM
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Yeh, YS
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Hsu, CC
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Chou, PT
The rational design and syntheses of a new series of Os-II complexes with formula [Os(fppz)(2)(CO)(L)] (1: L=4-dimethylaminopyridine; 2: L=pyridine; 3: L = 4,4'bipyridine; 4: L=pyridazine; 5: L = 4-cyanopyridine), bearing two (2-pyridyl)pyrazolate ligands (fppz) together with one carbonyl and one N-heterocyclic ligand at the axial positions are reported. Single-crystal X-ray diffraction studies of, for example, 2 reveal a distorted octahedral geometry in which both fppz ligands reside in the equatorial plane with a trans configuration and adopt a bent arrangement at the metal center with a dihedral angle of similar to 23 degrees, while the carbonyl and pyridine ligands are located at the axial positions. Variation of the axial N-heterocyclic ligand leads to remarkable changes in the photophysical properties as the energy gap and hence the phosphorescence peak wavelength can be tuned. For complexes 1 and 2 the solvent-polarity-independent phosphorescence originates from a combination of intraligand (3)pi-pi* ((ILCT)-I-3) and metal-to-ligand charge transfer transitions ((MLCT)-M-3). In sharp contrast, as supported by cyclic voltammetry measurements and theoretical calculations, complexes 3-5 exhibit mainly ligand-to-lilgand charge transfer (LLCT) transitions, resulting in a large dipolar change. The phosphorescence of complexes 3-5 thus exhibits a strong dependence on the polarity of the solvent, being shifted for example, from 560 (in C6H12) to 665 nm (in CH3CN) and from 603 (in C6H12) to 710 nm (in CH3CN) for complexes 3 and 5, respectively. The results clearly demonstrate that a simple, straightforward derivatization of the axial N-heterocyclic ligand drastically alters the excitation properties per se from intraligand charge transfer (ILCT) to LLCT transitions. The latter exhibit remarkable LLCT phosphorescence solvatochromism so that a broad range of color tunability can be achieved.
Mental poker game based on a bit commitment scheme through network
(2002-02-05)
Chou, JS
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Yeh, YS
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資訊工程學系
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Department of Computer Science
There are many schemes proposed on mental poker so far. Most of them are based on the composition of each player's private permutation of cards. Yet, each one is either too complex or has some drawbacks in it. In other words, no solution has come to reality. In this paper, we propose a permutation-free method, i.e. a bit commitment scheme, along with the RSA cryptosystem (Cryptography-Theory and Practice, CRC Press, Boca Raton, 1995; Public-key, Cryptography, Springer, Berlin, 1996) to implement the mental poker game. It is not only simple but also concise in concept. (C) 2002 Elsevier Science B.V. All rights reserved.