• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.216-219
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• 2002

정보통신의 발달과 인터넷의 확산으로 인해 정보보안의 필요성이 중요한 문제로 대두되면서 여러 종류의 암호 알고리즘이 개발되어 활용되고 있다. Substitution Permutation Networks(SPN)등의 블록 암호 알고리즘에서는 확산선형변환 행렬을 사용하여 안전성을 높이고 있다. 확산선형변환 행렬이 Maximum Distance Separable(MDS) 코드를 생성하면 선형 공격과 차분 공격에 강한 특성을 보인다. 본 논문에서는 선형변환 행렬이 MDS 코드를 생성하는 가를 판단하는 새로운 알고리즘을 제안한다. 입력 코드는 GF(2/sub□/)상의 원소들로 구성되며, 원소를 변수로 해석하여, 변수를 소거시키면서 선형변환행렬이 MDS 코드를 생성하는 가를 판단한다. 본 논문에서 제안한 알고리즘은 종래의 모든 정방 부분행렬이 정칙인가를 판단하는 알고리즘과 비교하여 연산 수행 시간을 크게 줄였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.7
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• pp.1462-1470
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• 2003

According to the necessity about information security as well as the advance of IT system and the spread of the Internet, a variety of cryptography algorithms are being developed and put to practical use. In addition the technique about cryptography attack also is advanced, and the algorithms which are strong against its attack are being studied. If the linear transformation matrix in the block cipher algorithm such as Substitution Permutation Networks(SPN) produces the Maximum Distance Separable(MDS) code, it has strong characteristics against the differential attack and linear attack. In this paper, we propose a new algorithm which cm estimate that the linear transformation matrix produces the MDS code. The elements of input code of linear transformation matrix over GF$({2_n})$ can be interpreted as variables. One of variables is transformed as an algebraic formula with the other variables, with applying the formula to the matrix the variables are eliminated one by one. If the number of variables is 1 and the all of coefficient of variable is non zero, then the linear transformation matrix produces the MDS code. The proposed algorithm reduces the calculation time greatly by diminishing the number of multiply and reciprocal operation compared with the conventional algorithm which is designed to know whether the every square submatrix is nonsingular.

• TTA Journal
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• s.95
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• pp.64-69
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• 2004

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.705-708
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• 2013

정보의 보안이 중요해지는 이 시점에 모바일이나 태블릿을 통한 악성 코드 및 기밀 유출이 증가하고 있다. 회사나 정부 기업쪽에서도 자체 기밀을 보호하기 위하여 많은 노력을 하고 있지만 개인 휴대품에 대한 보안은 아직 미흡한 실정이다. 본 연구에서는 모바일과 개인 태블릿에 관한 보안을 앱을 통한 것이 아닌 내장 프로그램으로 적용시켰다. 또한 일정 범위 내에서 조절할 수 있게 하여 보안 유출을 미연에 방지 할 수 있는 MDS 라이브러리 테스트 프로그램을 설계 및 구현을 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.123-136
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• 2004

In this paper, complexity and regularity of polynomial multiplication over $GF({2^n})$ are defined by using Hamming weight of rows and columns of the matrix ever GF(2) which represents polynomial multiplication. It is shown experimentally that in order to construct the block cipher robust against differential cryptanalysis, polynomial multiplication of substitution layer and the permutation layer should have high complexity and high regularity. With result of the experiment, a way of constituting S box and G function is suggested in the block cipher whose structure is similar to SEED, which is KOREA standard of 128-bit block cipher. S box can be formed with a nonlinear function and an affine transform. Nonlinear function must be strong with differential attack and linear attack, and it consists of an inverse number over $GF({2^8})$ which has neither a fixed pout, whose input and output are the same except 0 and 1, nor an opposite fixed number, whose output is one`s complement of the input. Affine transform can be constituted so that the input/output correlation can be the lowest and there can be no fixed point or opposite fixed point. G function undergoes linear transform with 4 S-box outputs using the matrix of 4${\times}$4 over $GF({2^8})$. The components in the matrix of linear transformation have high complexity and high regularity. Furthermore, G function can be constituted so that MDS(Maximum Distance Separable) code can be formed, SAC(Strict Avalanche Criterion) can be met, and there can be no weak input where a fixed point an opposite fixed point, and output can be two`s complement of input. The primitive polynomials of nonlinear function affine transform and linear transformation are different each other. The S box and G function suggested in this paper can be used as a constituent of the block cipher with high security, in that they are strong with differential attack and linear attack with no weak input and they are excellent at diffusion.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.291-300
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• 2002

In this paper, a way of constituting optimized S box and G function was suggested in the block cipher whose structure is similar to SEED, which is KOREA standard of 128-bit block cipher. S box can be formed with nonlinear function and an affine transform. Nonlinear function must be strong with differential attack and linear attack, and it consists of an inverse number over GF(2$\^$8/) which has neither a fixed point, whose input and output are the same except 0 and 1, nor an opposite flexed number, whose output is one's complement of the input. Affine transform can be constituted so that the input/output correlation can be the lowest and there can be no fixed point or opposite fixed point. G function undergoes diffusive linear transform with 4 S-box outputs using the matrix of 4$\times$4 over GF(2$\^$8/). G function can be constituted so that MDS(Maximum Distance Separable) code can be formed, SAC(Strict Avalanche Criterion) can be met, there can be no weak input, where a fried point, an opposite fried point, and output can be two's complement of input, and the construction of hardware can be made easy. The S box and G function suggested in this paper can be used as a constituent of the block cipher with high security, in that they are strong with differential attack and linear attack with no weak input and they are excellent at diffusion.