• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.1-15
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• 2003

${Cachin}^{[1]}$ defined the security of steganography theoretically at first, then ${Katzenbeisser}^{[2]}$ and ${Hopper}^{[3]}$ also discussed it on the different aspects. Unfortunately, because many steganographic systems couldnt overcome the statistical gap between a stego-cover and a pure cover, the secure steganography hasn' been evaluated yet. By the effectivel steganalysis algorithm, statistical test which was suggested by Westfel $d^{［4］}$, the attacker Wendy could select the stego-covers out of suspicious covers. Our newly developed algorithm which minimizes the changes of a pure cover by using the block cipher withstands a statistical test and has a similar embedding capacity in comparison with a simple LSB substitution steganography.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.372-381
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• 2001

In this paper SEED, the Korea Standard 128-bit block cipher algorithm is implemented with VHDL and mapped into one FPGA. SEED consists of round key generation block, F function block, G function block, round processing block, control block and I/O block. The designed SEED is realized in an FPGA but we design it technology-independently so that ASIC or core-based implementation is possible. SEED requires many hardware resources which may be impossible to realize in one FPGA. So it is necessary to minimize hardware resources. In this paper only one G function is implemented and is used for both the F function block and the round key block. That is, by using one G function sequentially, we can realize all the SEED components in one FPGA. The used cell rate after synthesis is 80% in Altem FLEXI0KlOO. The resulted design has 28Mhz clock speed and 14.9Mbps performance. The SEED hardware is technology-independent and no other external component is needed. Thus, it can be applied to other SEED implementations and cipher systems which use SEED.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.5 no.1
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• pp.25-36
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• 1995

Differential Cryptanalysis(DC) and Linear Cryptanalysis(LC) are considered to be efficient attack methods which could be applied to DES and other DES-like private key Cryptosystems. This paper analyzes the DC and LC attack to DES and design a 80-bit block Cipher (80-DES) which could be strong against DC and LC Attack.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.2
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• pp.73-80
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• 2015

In the various application environments on the internet, we use verified cipher algorithm to protect personal information. Even so, if an application method isn't proper, the information you want to keep can be intercepted. One of the representative examples of it is a PADDING ORACLE ATTACK. This thesis studied about STRP, MIKEY, CMS, IPSec, TLS, IPTV, an application environment which apply CBC operational mode based on block cipher and CBC padding method, and about whether we can attack against the Padding Oracle Attack as well as the vulnerable points.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.615-617
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• 1998

본 논문에서는 블록 암호 알고리즘을 위한 새로운 Dynamic-네트워크를 제시한다. Dynamic-네트워크 는 좋은 confusion과 diffusion 메카니즘을 제공한다. 어떠한 Dynamic-네트워크 {{{{ { 2}^{n }-비트(n >=1) }}}}길 이를 갖는 모든 평문을 입력으로 할 수 있으며, 일정 길이 이상의 모든 비트 스트링을 키로 사용할 수 있다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.67-80
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• 2002

In this article, a new block encryption algorithm FRACTAL is introduced. FRACTAL adopts 8-round Feistel structure handling 128 hit inputs and keys. Furthermore, FRACTAL possesses the provable security against DC and LC, which are known to he the most powerful attacks on block ciphers.

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.1-8
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• 2017

Lightweight Encryption Algorithm(LEA) was developed by National Security Research Institute(NSRI) in 2013 and targeted to be suitable for environments for big data processing, cloud service, and mobile. LEA specifies the 128-bit message block size and 128-, 192-, and 256-bit key sizes. In this paper, block cipher LEA algorithm which can encrypt and decrypt 128-bit messages is designed using Verilog-HDL. The designed IP for encryption and decryption has a maximum throughput of 874Mbps in 128-bit key mode and that of 749Mbps in 192 and 656Mbps in 256-bit key modes on Xilinx Vertex5. The cryptographic IP of this paper is applicable as security module of the mobile areas such as smart card, internet banking, e-commerce and IoT.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3138-3147
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• 2000

EC(Electronic Commerce) which is cone the virtual space through Internet, has the advantage of time and space. On the contrary, it also has weak point like security probelm because anybody can easily access to the system due to open network attribute of Internet. Theretore, we need the solutions that protect the EC security problem for safe and useful EC activity. One of these solution is the implemonlation of a strong cipher algorithm. YK2(YoungKu Kang) cipher algorithm proposed in this paper is advantage for the EC security and it overcomes the limit of the current 6/1 bits block cipher algorithm using 128 bits key length for input, output, encryption key and 32 rounds. Moreover, it is degigned for the increase of time complexity and probability calculation by adapting more complex design for key scheduling regarded as one of the important element effected to enciyption.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.564-568
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• 2002

정보보호 평가는 크게 시스템 평가인 CC평가와 암호모듈 평가인 CMVP평가고 나눌 수 있다. 본 논문은 암호모듈 평가 방법으로 북미 CMVP의 3가지 블록 알고리즘시험방법인 KAT(Known Answer Test), MCT(Monte Calro Test), MMT(Multi-block Message Test)를 JAVA환경에 적용하여 시범 구현하였다. 대상 알고리즘은 CMVP의 4가지 블록 알고리즘(DES, TDES, AES, Skipjack)을, 테스트 방법으로 MOVS, TMOVS, AESAVS를 선정하여 FIPS표준을 적용하였다. 구현 환경으로는 JCA기반의 Cryptix를 채택하여 CMVP의 블록 암호 알고리즘 테스트 시스템 중 일부를 구현하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1295-1305
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• 2017

There is SEED cryptosystem in domestic block cipher standard. This code was drafted by the Korea Information Security Agency (KISA) in October 1998 and underwent a public verification process in December of the same year, which resulted in the final amendment to improve safety and performance. Unlike DES, it is a 128-bit block cipher that has been passed through various processes and established in 2005 as an international standard. It is a block cipher with a pastel structure like DES, but the input bit block has been increased to 128 bits, double DES. In this paper, first, we introduce the general algorithm of SEED cryptosystem and analyzed mathematically generating principle of key-value which is used in F-function. Secondly, we developed a table that calculates the exponent of the primitive element ${\alpha}$ corresponding to the 8-bit input value of the S-function and finally analyzed calculating principle of S-function designed in G-function through the new theorem and example. Through this course, we hope that it is to be suggest the ideas and background theory needed in developing new cryptosystem to cover the weakness of SEED cryptosystem.