• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.1
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• pp.65-70
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• 2006

It is hewn that we can apply algebraic attacks on combiners with memory such as summation generators. [1,8] To apply algebraic attacks on combiners with memory, we need to construct algebraic relations between the keystream bits and the initial bits of the LFSRs. Until now, all known methods produce algebraic relations involving several consecutive bits of keystream. [l.4.8] In this paper, we show that algebraic relations involving only one keystream bit can be constructed for summation generators. We also show that there is an algebraic relation involving only one keystream bit for ISG (9) proposed by Lee and Moon. Using this fact, we analyze the keystream generators which generate the keystreams by combining summation generators.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.80-86
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• 2006

In this paper, we propose the PingPong-128(PP-128) keystream generator, based on summation generator. Proposed PingPong-128, a specific cipher of the PingPong Family, takes 128 bits key and 128 bit initial vector, has 258 bit internal state, and achieves a security level of 128 bits. The security analysis of PingPong-128 is presented, including the resistence to known attacks against the summation generator and other clock-controlled generators.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5
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• pp.1474-1481
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• 2000

The number of keystream cycle sequences has been proposed as a characteristic of binary sequence generator for cryptographic application, but in general the most of binary sequence generators have a single cycle. On the other hand, S-box has been used to block cipher for a highly nonlinear element and then we apply it to the stream cipher with a high crypto-degree. In this paper, we propose a multiple-cycle binary sequence generator based on S-box which has a high nonlinearity containing SAC property and analyze its period, linear complexity, randomness and the number of keystream cycle sequences.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.67-72
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• 2002

The number of keystream cycle sequences has been proposed as a characteristic of binary sequence generators for cryptographic applications, but in general most binary sequence generators have the only one-cycle sequence. In this paper, we propose a switching-tap LFSR as a basic function of a multiple-cycle binary sequence generator and the improved Rueppel's multiple-cycle generator. Finally we analyze its period, linear complexity, and the number of its keystream cycle sequences.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1011-1014
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• 2004

본 논문에서 제안된 Self_Decimated LM-128 키 수열 발생기(Keystream generator)는 2개의 비트 메모리 합산 수열발생기(summation generator)를 갖는 자체 클럭 조절형 키 수열 발생기(stream cipher)이다. Self_Decimated LM-128은 LM 계열에서 제시된 특수한 암호로 128비트 키와 128비트 초기 벡터 그리고 257 비트의 내부 상태를 가지며 128 비트의 보안 레벨을 유지한다. 알려진 보안 분석의 공격에 대비해서 2-비트 메모리를 이용한 합산 수열발생기와 자체 클럭 조절형 키 수열 발생기를 포함한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1702-1708
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• 2007

Dragon Stream Cipher is proposed for software base implementation in the eSTREAM project. Now this stream cipher is selected as a phase 3 focus candidate. Dragon is a new stream cipher contructed using a single word based NIFSR(non-linear feed back shift register) and 128/256 key/IV(Initialization Vector). Dragon is the keystream generator that produce 64bits of keystream. In this paper, we present an implementation of Drag(m stream cipher algorithm in hardware. Finally, the implementation is on Altera FPGA device, EP3C35F672I and the timing simulation is done on Altera's Quartus II. A result of 111MHz maximum clock rate and 7.1Gbps is throughput is obtained from the implementation.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.105-111
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• 2001

The shrinking generator is simple and stateable, and known that has good security properties. The bits of one output( $R_1$) are used to determine whether the corresponding bits of the second output will be used as part of the overall keystream. Two LFSRs consisting the generator generate pseudorandom sequences satisfying Golomb's postulates. We used this property to analyze the stream of LFSR $R_1$ of the generator.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.2
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• pp.25-32
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• 2006

In this paper, we propose a fast correlation attack on the shrinking and self-shrinking generator. This attack is an improved algorithm or the fast correlation attack by Zhang et al. at CT-RSA 2005. For the shrinking generator, we recover the initial state of generating LFSR whose length is 61 with $2^{15.43}$ keystream bits, the computational complexity of $2^{56.3314}$ and success probability 99.9%. We also recover the initial state of generating LFSR whose length is $2^{40}$ of the self-shrinking generator with $2^{45.89}$ keystream bits, the computational complexity of $2^{112.424}$ and success probability 99.9%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2507-2513
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• 2010

In this paper, we show that the shrinking generator with two LFSR whose characteristic polynomials are primitive is an interleaving generator and analyze phase shifts in shrunken sequence. Also for a given intercepted sequence of shrunken sequence, we propose. the method of reconstructing some deterministic bits of the shrunken sequence using phase shifts.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.9
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• pp.885-892
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• 2016

The nonlinear sequence generator called the shrinking generator was designed as nonlinear keystream generator composed by two maximum-length LFSRs. The shrunken sequences generated by the shrinking generator are included in the class of interleaved sequences and can be modelled as one of the output sequences of cellular automata (CA). In this paper, we propose a method for synthesizing a 90/150 CA-based sequence generator to generate a family of sequences with the same characteristic polynomial as the shrunken sequences.