• Journal of the Korea Institute of Information Security & Cryptology
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• v.8 no.2
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• pp.37-46
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• 1998

본 논문에서는 스트림 암호 구현 시 하드웨어 설계가 용이한 고속 자기 상관기와 이를 이용한 개선된 키 수열 동기 방식을 제안하였다. 제안 방식은 키 수열 동기시 잡음이 무선 채널에서도 동기를 유지할 수 있는 고속, 고신뢰도 초기 키 수열 동기 방식이며, 기존 방식보다 복잡도를 크게 줄 여서 하드웨어 구현이 용이하도록 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2181-2190
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• 1997

The synchronous stream cipher has the problem of synchronization loss by cycle slip. Synchronization loss make the state which sender and receiver can't communicate and it may make the receiving system disordered. To lessen the risk, we usually use a continuous resynchronization which achieve resynchronization at fixed timesteps by inserting synchronization pattern and session key. While we can get effectively resynchronizationby continuous resynchronization, there are some problems. In this paper, we proposed an adaptive resynchronization algorithm for cipher system using LAPB protocol. It is able to solve the problem of the continunous resynchronization.The proposed adaptive algorithm make resynchronization only in the case that the resynchronization is occurred by analyzing the address field of LAPB. It measure the receiving rate of the address field in the decesion duration. If the receiving rate is smaller than threshold value, it make resynchronization or not. By using adaptively resynchronization, it solves the problems of continunous resynchronization. When the proposed adaptive algorithm is applied to the synchronous stream cipher system which is used in X.25 packet network, it reduced the time for resynchronization by ten times. It means that 11.3% of total data for transmit is compressed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1765-1773
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• 1997

The communication systems which include PLL may have cycle clip problem because of channel noise. The cycle slip problem occurs the synchronization loss of communication system and it may be fatal to the synchronous stream cipher system. While continuous resynchronization is used to lessen the risk of synchronization it has some problems. In this paper, we propose the method which solve the problems by using continuous resynchronization with the clock recovery technique. If the counted value of real clock pulse in reference duration is not same as that of normal state, we decide the cycle slip has occurred. The damaged clock by cycle slip is compensated by adding or subtracting the clock pulse according to the type of cycle slip. It reduced the time for resynchronization by twenty times. It means that 17.8% of data for transmit is compressed.

• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.552-557
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• 2009

One-time passwords are used just once and discarded, which makes it more secure than the repeatedly used conventional passwords. This paper proposes a challenge-response based one-time password generator on a user's mobile phone always carried with the user. The generator can provide an additional authentication for a user to issue a money transfer request within his Internet banking session on a PC. A currently used device for Internet banking generates a password that changes every 30 seconds or so, which allows a man-in-the-middle to use it for stealing money within the 30 seconds. Unlike such a device, the proposed generator resists against the man-in-the-middle attack by a novel challenge-response scheme, provides better accessability and protection against stolen devices. As the currently used devices do, it prevents any unauthorized transfer even if the victim's all other credentials are revealed through his PC infected with spyware such as a keyboard logger.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.97-99
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• 2022

대규모 양자컴퓨터가 등장하면 기존 암호체계가 더 이상 안전하지 않을 것이라 예상한다. 양자 알고리즘인 Grover's brute-force 알고리즘은 대칭키 암호에 대한 attack을 가속화 시켜 보안강도를 감소시킨다. 따라서 양자컴퓨터의 가용 자원이 암호공격에 필요한 자원에 도달했을 때, 공격 대상 암호가 깨지는 시점으로 보고 있다. 많은 선행 연구들은 암호를 양자회로로 구현하여 공격에 필요한 자원을 추정하고 암호에 대한 양자 강도를 확인하였다. 본 논문에서는 이러한 연구동기로 ARX 구조의 SIMECK 경량암호에 대한 양자회로를 처음으로 제안한다. 우리는 SIMECK 양자회로에 대한 최적의 양자회로 구현을 제시하고 각 함수의 동작을 설명한다. 마지막으로 SIMECK 양자회로에 대한 양자자원을 추정하고 SIMON 양자회로와 비교하여 평가한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.20-25
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• 2001

블록 암호 알고리즘과 블록 암호의 운영모드 및 메시지 인증 알고리즘에 대한 의사 난수성의 증명은 근래의 암호 분석에서 구조적인 안전성을 증명을 위한 기법으로 커다란 안전성의 평가 방법으로 자리 매김하고 있다. 본 논문에서는 비동기식(W-CDMA) 3세대 이동통신 3GPP에서의 MAC 알고리즘의 안전성을 의사 난수성에 기반한 concrete security 관점에서의 안전성에 대해 알아본다. 즉, 3GPP-MAC 알고리즘의 구조적인 안전성에 대한 증명을 다룬다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1991.11a
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• pp.40-48
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• 1991

McEliece 공개키 암호체계에 대한 새로운 암호해독적 공격이 제시되어진다. 기존의 암호해독 algorithm이 exponential-time의 complexity를 가지는 반면, 본고에서 제시되어지는 algorithm은 polynomial-time의 complexity를 가진다. 모든 linear codes에는 systematic generator matrix가 존재한다는 사실이 본 연구의 동기가 된다. Public generator matrix로부터, 암호해독에 사용되어질 수 있는 새로운 trapdoor generator matrix가 Gauss-Jordan Elimination의 역할을 하는 일련의 transformation matrix multiplication을 통해 도출되어진다. 제시되어지는 algorithm의 계산상의 complexity는 주로 systematic trapdoor generator matrix를 도출하기 위해 사용되는 binary matrix multiplication에 기인한다. Systematic generator matrix로부터 쉽게 도출되어지는 parity-check matrix를 통해서 인위적 오류의 수정을 위한 Decoding이 이루어진다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.63-70
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• 2005

LINK16 is a system which is designed to maximize performance in a particular tactical environment with high levels of jamming. In this paper, transmission performance of synchronization pattern for cipher communication in aerial tactical communication link is presented. Transmission architecture of operating mode (standard DP, P2SP, P2DP, P4mode) in LINK16 network is discussed, and an effect of synchronization pattern, a quality of degraded effect of transmission communication for collision probability between hopping frequencies and fading channel in crypto communication is analyzed.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.77-83
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• 2001

In recent years, the AES in North America and the NESSIE project in Europe have been in progress. Six proposals have been submitted to the NESSIE project including the LILI-128 by Simpson in Australia in the synchronous stream cipher category. These proposals tend towards a design with parallelism of the algorithms in order to facilitate speed-up. In this paper, we consider the PS-LFSR and propose the effective implementation of various nonlinear combiners: memoryless-nonlinear combiner, memory-nonlinear combiner, nonlinear filter function, and clock-controlled function. Finally, we propose m-parallel SUM-BSG and LILI-l28's parallel implementation as examples, and we determine their securities and performances.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.1
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• pp.7-14
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• 2001

Among zero-suppression (ZS) algorithms proposed for synchronous stream cipher system, ZS-1 has the difficulty on the implementation of stream cipher system, ZS-2 has a weakness of channel error propagation, and ZS-3 has the complexity on the hardware. Because each algorithm must be chosen carefully to the application system, in this paper, we propose a criterion of the system adapted from the simulated results on the parameter changed.