• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.333-337
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• 2006

Symmetric block ciper algorithm consists of a chains of operations such as permutation and substitution. There exists four kinds of operation mode, CBC, ECB, CFB, and OFB depending on the operation paradigm. Since the final ciper text is obtained through the many rounds of operations, it consumes much time. This paper proposes a pipelined design methodology which can improve the speed of crypto operations in ECB mode. Because the operations of the many rounds are concatenated in serial and executed concurrently, the overall computation time can be reduced significantly. The experimental result shows that the method can speed up the performance more than ten times.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.5
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• pp.124-130
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• 2017

Character encoding is the method used to represent characters or symbols on a computer, and there are many encoding detection software tools. For the widely used encoding detection software"uchardet", the accuracy of encoding detection of unmodified normal text document is 91.39%, but the accuracy of language detection is only 32.09%. Also, if a text document is encrypted by substitution, the accuracy of encoding detection is 3.55% and the accuracy of language detection is 0.06%. Therefore, in this paper, we propose encoding and language detection of text document using the deep learning algorithm called LSTM(Long Short-Term Memory). The results of LSTM are better than encoding detection software"uchardet". The accuracy of encoding detection of normal text document using the LSTM is 99.89% and the accuracy of language detection is 99.92%. Also, if a text document is encrypted by substitution, the accuracy of encoding detection is 99.26%, the accuracy of language detection is 99.77%.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.11
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• pp.271-276
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• 2019

Conventional ARIA algorithm which is used LUT based-S-Box is fast the processing speed. However, the algorithm is hard to applied to small portable devices. This paper proposes the hardware design of optimized ARIA crypto-processor based on the modified composite field S-Box in order to decrease its hardware area. The Key scheduling in ARIA algorithm, both diffusion and substitution layers are repeatedly used in each round function. In this approach, an advanced key scheduling method is also presented of which two functions are merged into only one function for reducing hardware overhead in scheduling process. The designed ARIA crypto-processor is described in Verilog-HDL, and then a logic synthesis is also performed by using Xilinx ISE 14.7 tool with target the Xilnx FPGA XC3S1500 device. In order to verify the function of the crypto-processor, both logic and timing simulation are also performed by using simulator called ModelSim 10.4a.

• Convergence Security Journal
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• v.16 no.7
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• pp.85-91
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• 2016

Block cipher is one of the prominent and important elements in cryptographic systems and study on the minimal construction is a major theme in the cryptographic research. Even and Mansour motivated by the study suggested a kind of block cipher called the Even-Mansour scheme in the early 1990s. It is a very simple cipher with one permutation and two secret keys. There have been many studies on the Even-Mansour scheme and security analysis of the scheme. We explain the Even-Mansour scheme and simplify those attacks on the Even-Mansour scheme with mathematical language. Additionally, we show that Pollard's rho attack to the discrete logarithm problem can be used to attack the Even-Mansour scheme with the same complexity of the Pollard's rho attack.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1419-1429
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• 2014

In this paper, we consider the development of encryption of DES (data encryption standard) based on Microsoft Excel Macro, which was adopted as the FIPS (federal information processing standard) 46 of USA in 1977. Concrete explanation of DES is given. Algorithms for DES encryption are adapted to Excel Macro. By repeating the 16 round which is consisted of diffusion (which hide the relation between plain text and cipher text) and the confusion (which hide the relation between cipher key and cipher text) with Excel Macro, we can easily get the desired DES cipher text.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.646-648
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• 1999

본 논문에서는 RSA 암호 알고리즘의 핵심 계산 과정인 모듈로 곱셈 연산의 효율적인 하드웨어 구현을 위해 새로운 알고리즘과 하드웨어 구조를 제시한다. 기존의 몽고메리 알고리즘이 LSB 우선 방법을 사용한 것과는 달리 여기서는 MSB 우선 방법을 사용하였으며, RSA 암호 시스템에서 키가 일정 기간 동안 변하지 않고 유지된다는 점에 착안해 계수(Modulus)에 대한 보수(Complements)를 미리 계산해 놓고 이를 이용하여 모듈로 감소 처리를 간단히 덧셈으로 치환하도록 하였다. 보수들을 저장할 몇 개의 레지스터와 그들 중 하나를 선택하기 위한 간단한 멀티플렉서(Multiplexer)만을 추가함으로써 몽고메리 알고리즘이 안고 있는 홀수 계수 조건과 사후 연산이라는 번거로움을 없앨 수 있다. 본 논문에서 제안하는 알고리즘은 하드웨어 복잡도가 몽고메리 알고리즘과 비슷하며 그 내부 계산 구조를 보여주는 DG(Dependence Graph)의 지역 연결성 (Local Connection), 모듈성(Modularity), 데이터의 규칙적 종속성 (Regular Data Dependency)등으로 인한 실시간 고속 처리를 위한 VLSI 구현에 적합하다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.595-599
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• 1999

본 논문에서는 카오스 현상을 나타내는 수식을 변형하여 암호시스템이나 PN(pseudo-noise)시퀸스에 적용하기 위하여 복잡한 카오스 신호를 발생시키는 하이퍼카오스 VP 사상(HVPM, Hyper chaos Volume Preserving Maps)과 이들간의 카오스 동기화를 제안한다. 단계별 모듈러(modulus) 함수를 이용하여 랜덤한 카오스 신호를 발생시키기 위하여 이산시간(discrete-time) HVPM 모델을 설정하고, 수치해석 실험으로 아날로그 카오틱시퀸스(CAS. chaotic analog sequence)의 특징을 분석한다. 그리고 HVPM의 신호를 기존의 단순한 PC(Pecora, Carroll)방법을 응용한 치환동기화 (synchronous substitution)를 이용하여 구동 및 응답시스템간의 카오스 동기화(chaos synchronization) 제어를 한다. 수치실험에서 카오스 신호가 갖는 특징들을 확인할 수 있었으며, 치환동기시스템에서 효과적인 카오스 동기화가 수행됨을 증명할 수 있었다.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.3
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• pp.9-17
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• 2012

In this paper, we propose a SPN 256 bit block cipher so called XSB(eXtended SPN Block cipher) which has a symmetric structure in encryption and decryption. The proposed XSB is composed of the even numbers of N rounds where the first half of them, 1 to N/2-1 round, applies a pre-function and the last half of them, N/2+1 to N round, employs a post-function. Each round consists of a round key addition layer, a substiution layer, a byte exchange layer and a diffusion layer. And a symmetry layer is located in between the pre-function layer and the post-function layer. The symmetric layer is composed with a multiple simple bit slice involution S-Boxes. The bit slice involution S-Box symmetric layer increases difficult to attack cipher by Square attack, Boomerang attack, Impossible differentials cryptanalysis etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.316-322
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• 2017

This paper suggests an efficient software implementation of lightweight encryption algorithm PRESENT which supports for secret key lengths of 80-bits. Each round of PRESENT is composed of the round key addition, substitution, and permutation and is repeated 31 times. Bo Zhu suggested combined substitution and permutation for efficient operation so that encryption throughput has been increased 2.6 times than processing substitution and permutation at separate times. The scheme that suggested in this paper improved the scheme of Bo Zhu to reduce the number of operation for the round key addition, substitution, and permutation. The scheme that suggested in this paper has increased encryption throughput up to 1.6 times than the scheme of Bo Zhu but memory usage has been increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.41-48
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• 2013

An efficient encryption algorithm based on the Data Encryption Standard (DES) for personal cloud computing environments is presented. The proposed algorithm improves data privacy, security and also encryption speed, compared with the triple DES. The improvement of the proposed algorithm stems from enhanced privacy inherent from the use of spread random interleaver in the place of the known substitution table for initial and final permutations in the DES algorithm. The simulation results demonstrate that the interleaver based DES (I-DES) is found to run faster than the triple DES algorithm and also offer improved security. The proposed algorithm also offers encryption for variable-length data using the Cipher Block Chaining (CBC).