Browsing by Author "CHANG, CC"

Now showing 1 - 20 of 27

A CONNECTIONIST APPROACH FOR THRESHOLDING
(1992)
CHANG, CC
;
CHANG, CH
;
HWANG, SY
;
資訊工程學系
;
Department of Computer Science
A LETTER-ORIENTED PERFECT HASHING SCHEME BASED UPON SPARSE TABLE COMPRESSION
(1991-01-01)
CHANG, CC
;
WU, TC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In this paper, a new letter-oriented perfect hashing scheme based on Ziegler's row displacement method is presented. A unique n-tuple from a given set of static letter-oriented key words can be extracted by a heuristic algorithm. Then the extracted distinct n-tuples are associated with a 0/1 sparse matrix. Using a sparse matrix compression technique, a perfect hashing function on the key words is then constructed.
A NEW ALGORITHM AND ITS VLSI ARCHITECTURE DESIGN FOR CONNECTED COMPONENT LABELING
(1994)
JEAN, SD
;
LIU, CM
;
CHANG, CC
;
CHEN, Z
;
資訊工程學系
A NEW APPROACH TO MODEL CMOS LATCHUP
(1985)
WU, CY
;
YANG, YH
;
CHANG, C
;
CHANG, CC
;
工學院
A PASSWORD AUTHENTICATION SCHEME BASED ON DISCRETE LOGARITHMS
(1991)
WU, TC
;
CHANG, CC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
ADAPTIVE PACKET EQUALIZATION FOR INDOOR RADIO CHANNEL USING MULTILAYER NEURAL NETWORKS
(1994-08-01)
CHANG, PR
;
YEH, BF
;
CHANG, CC
;
交大名義發表
;
電信工程研究所
This paper investigates the application of the multilayer perceptron structure to the packet-wise adaptive decision feedback equalization of a M-ary QAM signal through a TDMA indoor radio channel in the presence of intersymbol interference (ISI) and additive Gaussian noise. Since the multilayer neural networks are capable of producing complex decision regions with arbitrarily nonlinear boundaries, this would greatly improve the performance of conventional decision feedback equalizer (DFE) where the decision boundaries of conventional DFE are linear. However, the applications of the traditional multilayer neural networks have been limited to real-valued signals. To tackle this difficulty, a neural-based DFE is proposed to deal with the complex QAM signal over the complex-valued fading multipath radio channel without performing time-consuming complex-valued back-propagation training algorithms, while maintaining almost the same computational complexity as the original real-valued training algorithm. Moreover, this neural-based DFE trained by packet-wise backpropagation algorithm would approach an ideal equalizer after receiving a sufficient number of packets. In this paper, another fast packet-wise training algorithm with better convergence properties is derived on the basis of a recursive least-squares (RLS) routine. Results show that the neural-based DFE trained by both algorithms provides a superior bit-error-rate performance relative to the conventional least mean square (LMS) DFE, especially in poor signal to noise ratio conditions.
ALGEBRAIC OPERATIONS ON ENCRYPTED RELATIONAL DATABASES
(1993-01-01)
WU, TC
;
YEH, YS
;
CHANG, CC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In this paper, we consider the problem of performing algebraic operations and their extensions with encrypted relational databases. Each tuple of a relation is enciphered by a cryptosystem based on the extended Chinese remainder theorem. We show that one can perform the Projection, the Cartesian Product and their composite operations, such as performing the Projection followed by the Cartesian Product and performing Cartesian Product followed by the Projection, with the encrypted tuples directly without deciphering them. We also show that there does not exist a secure way to protect data for performing Comparison operations, such as Selection, Union,... , etc., with encrypted relational databases.
AN AUTHENTICATION-COMBINED ACCESS-CONTROL SCHEME USING A ONE-WAY FUNCTION
(1994-03-01)
WU, TC
;
CHANG, CC
;
YEH, YS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In this paper, we propose an authentication-combined access control scheme for information protection systems. Let a(ij) be the access privilege of User i to File j. Initially, by the Diffie-Hellman public key distribution scheme, the system and the users are assigned distinct secret keys, and their corresponding public keys, respectively. Let K(s) be the secret key and y(s) be the public key of the system, and let K(i) be the secret key and y(i) be the public key of the User i. By using a predefined one-way function F, we compute r(ij) = F(K(i), y(s), a(ij)). Reversely, the access privilege can be retained as a(ij) = F(K(s), y(i), r(ij)). Being different from the previously proposed schemes, our scheme is safer and the user's secret key is used not only for computing the corresponding access privilege to the intended file, but also for authenticating the requesting user not to illegitimately access the protected files. The proposed scheme is simple to establish. Besides, it can perform the access control in dynamic environments, such as change access privileges and insert/delete users or files.
AN EFFICIENT TIMING MODEL FOR CMOS COMBINATIONAL LOGIC GATES
(1985)
WU, CY
;
HWANG, JS
;
CHANG, C
;
CHANG, CC
;
電控工程研究所
AN ENCRYPTION/SIGNATURE SCHEME WITH LOW MESSAGE EXPANSION
(1995-07-01)
HWANG, SJ
;
CHANG, CC
;
YANG, WP
;
資訊工程學系
;
Department of Computer Science
Secrecy, authenticity and integrity are three major services provided by the public key cryptography. To provide these three services via the ElGamal public key cryptosystem and Signature scheme, the message expanding ratio is four and the overhead of communication is heavy. In this paper, a concurrent encryption/signature scheme will be proposed to provide these three services with a lower message expanding ratio. In the new scheme, the signer can encrypt and sign the message concurrently so the signature that serves as the ciphertext is a pair of integers. Thus the message expanding ratio can be decreased to two.
BROADCASTING CRYPTOSYSTEM IN COMPUTER-NETWORKS USING INTERPOLATING POLYNOMIALS
(1991-07-01)
CHANG, CC
;
WU, TC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
Based on the characteristics of the interpolating polynomials and some properties of the Euclidean geometry, a cryptosystem for broadcasting secrets in computer networks is presented. It is assumed that there is a central authority server (CAS) in a network system. Each principal of the network owns a secret point, known only to the principal and the CAS. When a secure broadcasting request is initiated, the CAS computes an interpolating polynomial P(x) on the secret points owned by the originator and the legal recipient(s). The CAS then cleverly reveals some public points to let the originator and legal recipient(s) reconstruct P(x), whereas illegal recipients are unable to do so. With these public points and a value c, the originator has P(c) as the encryption/decryption key, and can broadcast c and the message encrypted by P(c) in the network. For the legal recipients, P(x) can be reconstructed, and thus P(c) obtained. Since the legal recipients cannot obtain the exact P(x), they have no way of finding the decryption key.
COLOR CORRECTION FOR SCANNER AND PRINTER USING B-SPLINE CMAC NEURAL NETWORKS
(1994)
CHANG, PR
;
CHANG, CC
;
電信工程研究所
;
Institute of Communications Engineering
CONTROLLING THE ACCESS REQUESTS IN AN INFORMATION PROTECTION SYSTEM
(1993-01-01)
CHANG, CC
;
WU, TC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A new mechanism used for controlling the access requests in information systems is proposed. In our scheme, each access privilege associates to a recursively generated function based on Newton's interpolating polynomial. The insertion of a new user/file into the system and deletion of an old user/file from the system can be easily implemented. Besides, the updating of a privilege of a user to a file can also be successfully implemented without reconstructing all associated functions.
CRYPTOGRAPHIC KEY ASSIGNMENT SCHEME FOR ACCESS-CONTROL IN A HIERARCHY
(1992-05-01)
CHANG, CC
;
HWANG, RJ
;
WU, TC
;
資訊工程學系
;
Department of Computer Science
A cryptographic key assignment scheme for access control in a user hierarchy is proposed. The users and their owned information items are classified into disjoint sets of security classes where the hierarchy on security classes is an arbitrary partial order. Based on Newton's interpolation method and a predefined one-way function, each security class C(i) is assigned a secret key SK(i) and some public parameters (P1i, P2i). The information items owned by the security class C(i) are encrypted by an available symmetric cryptosystem with the enciphering key SK(i). Through the computing of the assigned security key and the public parameters, only the security class in the higher level can derive any of his successors' secret keys. Thus, only the security classes in the higher level can access the information items owned by the security classes in the lower level. We also show that our proposed scheme is not only secure but also practical.
ITERATION-LEVEL PARALLEL EXECUTION OF DO LOOPS WITH A REDUCED SET OF DEPENDENCE RELATIONS
(1987-10-01)
CHEN, Z
;
CHANG, CC
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交大名義發表
;
資訊工程學系
;
National Chiao Tung University
MODIFIED CHANG-HWANG-WU ACCESS-CONTROL SCHEME
(1993-11-25)
HWANG, MS
;
YANG, WP
;
CHANG, CC
;
資訊工程學系
;
Department of Computer Science
It is found that some security classes in the Chang-Hwang-Wu access control scheme can be combined to derive the secret key of their immediate ancestor in some cases. Some slight modifications to the proposed scheme to enhance the security levels are also given.
ON THE DESIGN OF VLSI ARCHITECTURES FOR PARALLEL EXECUTION OF DO LOOPS
(1990-04-01)
CHEN, Z
;
CHANG, CC
;
CHIA, TL
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資訊科學與工程研究所
;
Institute of Computer Science and Engineering
PASSWORD AUTHENTICATION USING NEWTON INTERPOLATING POLYNOMIALS
(1991)
LIN, CH
;
CHANG, CC
;
WU, TC
;
LEE, RCT
;
資訊科學與工程研究所
A password authentication mechanism based upon Newton's interpolating polynomial and a strong cryptographic operation such as DES (data encryption standard) is proposed in this paper. The mechanism can respond to any login request very efficiently. It is suitable for real-time applications and can be implemented in microcomputer system. With the properties of Newton's interpolating polynomial, high system performance can be achieved. The basic idea of our method is that users in the system are congregated together. Any illegal modification by an intruder to some user's parameter on the host tables will influence the others and can be easily detected. However, legitimate modification of password could be made efficiently.
PERFORMANCE ANALYSES OF CARTESIAN PRODUCT FILES AND RANDOM FILES
(1984)
CHANG, CC
;
DU, MW
;
LEE, RCT
;
資訊工程學系
;
Department of Computer Science
REMOTE PASSWORD AUTHENTICATION WITH SMART CARDS
(1991-05-01)
CHANG, CC
;
WU, TC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
A remote password authentication scheme based on the Chinese remainder theorem is proposed. The scheme can verify the remote password without verification tables. In the initial phase, the password generation centre generates and assigns a password corresponding to each user. The ideas of smart cards and the identity-based signature scheme introduced by Shamir are employed in this phase. Each user possesses a smart card for later login and authentication. In the login phase, the user submits the identity and password associated with the smart card. In the authentication phase, the system verifies the remotely submitted password to check if the login request is accepted or rejected. A signature scheme and communication timestamps are provided in the authentication phase against the potential attacks of replaying a previously intercepted login request.