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This paper proposes a new secret-key block cipher algorithm called MKC1. MKC1 is a Feistel-type block cipher with variable block length, key length, and number of rounds. The merits of this algorithm are that numerous structures can be formed by selecting the encryption functions and that cellular automata, which can ensure an immense number of structures, and power functions over a finite field, which have strong resistance to differential and linear attacks, are used for the encryption functions. These features increase MKC1's resistance to exhaustive key searches and analytical cryptanalysis. In addition, rules that are relatively powerful as encryption functions among the total of 256 rules for one-dimensional, two-state, neighborhood-three cellular automata were found to practically correspond to Class 3 of Wolfram's classification scheme. The results of computer experiments indicate that MKC1 is several times faster than DES. The industrial value of this algorithm was confirmed, by implementing it in an automatic electronic ticket system using a contactless IC card. [ABSTRACT FROM AUTHOR]

With a view to carrying out a highly accurate and fast time domain analysis of a lossy nonuniform transmission line, a method is described for application of the FDTD method to a finitely long lossy nonuniform transmission line. The present method is applied to a parabolic transmission line as one variety of nonuniform transmission line and a step response analysis is performed. By comparison with an analytical solution and other methods, the effectiveness of the method is confirmed. Also, the step response at the output end of a lossy nonuniform transmission line is almost a step waveform under conditions different from the distortionless transmission condition of a uniform line. Based on this result, a method is described for approximating the step response waveform at the output end of a lossy parabolic line to a step waveform. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 85(8): 1–10, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10006 [ABSTRACT FROM AUTHOR]

With a view to accurate and fast time domain analysis of nonuniform transmission lines, a method is presented for applying the FDTD method to a finite length nonuniform transmission line. A step response analysis is carried out for a parabolic line as one of the nonuniform transmission lines. Effectiveness of this approach is confirmed by comparison with analytical solutions and other methods. An equation for the voltage at the initial rising duration of the step response of a nonuniform transmission line is derived. It is shown that if the nonuniform transmission line has the characteristic impedance with a continuous distribution the initial arriving voltage can be determined by the characteristic impedance at both ends of the transmission line. As an application, a method is described for approximating the step response waveform of a parabolic line to a step wave. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 22–31, 2002 [ABSTRACT FROM AUTHOR]

We propose a cryptosystem with a choice of encryption keys. A knapsack cryptosystem with a choice of encryption keys may be difficult to cryptanalyze or to analyze with the LLL algorithm of a typical cryptanalysis algorithm in the linear cipher. This cryptosystem has plaintext and multiple encryption keys not corresponding 1:1 with each other and chooses the appropriate one from several encryption keys. By using the master decryption key, each ciphertext encrypted by an individual encryption key can always be decrypted by an individual encryption key can always be decrypted uniquely. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(7): 37–43, 1997 [ABSTRACT FROM AUTHOR]

Y-type and Z-type parabolic-taper single-mode transmission lines and their equivalent circuits are first discussed. Then, by superposition of two of the above single modes, the TEM mode along a parabolic-taper coupled transmission line (PTCTL) is analyzed. According to the choice of Y-type or Z-type for tapered single modes and the choice of combinations of balanced-unbalanced modes or open-short line modes as two independent superposed modes. there can be six types of PTCTL. Their equivalent circuits are also easily shown. Through the superposition of the voltages and currents of two Y-type single-mode parabolic-taper lines, a Y-type parabolic-taper coupled two-wire line is obtained. Similarly, from two Z-type single-mode parabolic-taper lines, a Z-type parabolic-taper coupled two-wire line is obtained. Furthermore, from a Y-type parabolic-taper line and a Z-type parabolic-taper line, we derive a mixed type of parabolic-taper coupled two-wire line. In any case there are two forms of combinaction, balanced-unbalanced modes and short-open line modes as superposition of two independent modes. An obtained nonuniform coupled two-wire line dogs not always have the same taper. A special case of interest is that in which one of the two wires of a coupled line has decreasing taper and the other has increasing taper. Finally, a low-pass filter is designed by the use of nonuniform coupled transmission lines and it is shown that the line length along the axis can be reduced. [ABSTRACT FROM AUTHOR]

This paper discussed the measure of information for the event using the probability theory by Dempster and Shefer. By providing various kinds of information to the event containing an ambiguitym the ambiguity us gradually decreased to define the event in a clearer way. The combination rule by Dempster is most suited to represent the combinations cab be made for Dempster's combination rule. Then using the upper and lower probabilities defined by the basic probability of the event, the upper and lower information measures are defined, followed by the discussion of their properties. The lower probability of a set (event) us defined as the sum of basic probabilities of all subsets in the set, and the upper probability is defined as the sum of basic probability is defined as the sum of probabilities of all sets which contain an element of the set. Thus, the upper and lower information measures can be interpreted as the measures of information concerning the message with ambiguity. Finally, several examples are discussed, determining the information measure for the message containing ambiguity. [ABSTRACT FROM AUTHOR]