- This thesis consists of three chapters. Chapter 1 is general introduction to information theory, cryptology, coding theory. Let $F_n^2$ be the n-dimensional vector space over $\text{GF}(2).$ Chapter 2 deals with expansive permutation on $F_2^n$ that is used to be the cryptographic function in S-box of DES. In Section 2 of the Chapter 2, we define a permutation P on $F_2^n$ to be the locally expanding permutation if P satisfies the following condition: For Hamming distance d and positive integers r,s, if the elements x,y in $F_2^n$ satisfies d(x,y)=r, then d(p(x),p(y))≥s.(See Definition 2.2.1.) And we show some simple properties of the locally expanding permutation. In Section 3 of the Chapter 2, we define a permutation P of $F_2^n$ to be maximally separating permutation if P satisfies the following condition: For Hamming distance d and non-negative integer k, we first define the metric $d_k^P$ on $F_2^n$ as $d_k^P(x,y)=max_{0≤i≤k}{d(P^i(x),P^i(y))}$ for x,y in $F_2^n$, where $P^i$ means i-times composition of P. If there exists integer $k≥0$ such that for all x,y in $F_2^n$ with x≠y, $d_k^P(x,y)=n$, we define P to be maximally separating permutation on $F_2^n.$(See Definition 2.3.1.) In Theorem 2.3.3, we show that the only two kinds of permutations can be maximally separating permutation. But, in view of Definition, a locally expanding permutation seems to be strong candidate for maximally separating permutation. However, in the last Remark of Section 3 of the Chapter 2, we show that there is no strong relationship between locally expanding permutation and maximally separating permutation. Chapter 3 deals with the decoding algorithm of a syndrome-distribution decoding of mols $L_p$ codes. Let P be an odd prime number. We introduce simple and useful decoding algorithm for orthogonal Latin square codes of order p. Let H be the parity check matrix of orthogonal Latin square code. For any x∈ GF$(p)^n,$ we call $xH^T$ the syndrome of x. This method is based on th...

- Advisors
- Hahn, S.
*researcher*; 한상근*researcher*

- Publisher
- 한국과학기술원

- Issue Date
- 1999

- Identifier
- 156124/325007 / 000945087

- Language
- eng

- Description
학위논문(박사) - 한국과학기술원 : 수학과, 1999.8, [ 28p. ]

- Keywords
부호 이론; 팽창치환; 암호론; Coding theory; Expansive permutation; Cryptology; Information theory; 정보 이론

- Appears in Collection
- MA-Theses_Ph.D.(박사논문)

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