• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.29-40
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• 2005

In this paper we consider the security of recently proposed software-orienred stram cipher HELIX, SCREAM, MUGI, and PANAMA against algebraic attacks. Algebraic attack is a key recovery attack by solving an over-defined system of multi-variate equations with input-output pairs of an algorithm. The attack was firstly applied to block ciphers with some algebraic properties and then it has been mon usefully applied to stream ciphers. However it is difficult to obtain over-defined algebraic equations for a given cryptosystem in general. Here we analyze recently proposed software-oriented stream ciphers by constructing a system of equations for each cipher. furthermore we propose three design considerations of software-oriented stream ciphers.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.3-16
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• 2008

A Wireless Sensor Network (WSN for short) is a wireless network consisting of distributed small devices which are called sensor nodes or motes. Recently, there has been an extensive research on WSN and also on its security. For secure storage and secure transmission of the sensed information, sensor nodes should be equipped with cryptographic algorithms. Moreover, these algorithms should be efficiently implemented since sensor nodes are highly resource-constrained devices. There are already some existing algorithms applicable to sensor nodes, including public key ciphers such as TinyECC and standard block ciphers such as AES. Stream ciphers, however, are still to be analyzed, since they were only recently standardized in the eSTREAM project. In this paper, we implement over the MicaZ platform nine software-based stream ciphers out of the ten in the second and final phases of the eSTREAM project, and we evaluate their performance. Especially, we apply several optimization techniques to six ciphers including SOSEMANUK, Salsa20 and Rabbit, which have survived after the final phase of the eSTREAM project. We also present the implementation results of hardware-oriented stream ciphers and AES-CFB fur reference. According to our experiment, the encryption speeds of these software-based stream ciphers are in the range of 31-406Kbps, thus most of these ciphers are fairly acceptable fur sensor nodes. In particular, the survivors, SOSEMANUK, Salsa20 and Rabbit, show the throughputs of 406Kbps, 176Kbps and 121Kbps using 70KB, 14KB and 22KB of ROM and 2811B, 799B and 755B of RAM, respectively. From the viewpoint of encryption speed, the performances of these ciphers are much better than that of the software-based AES, which shows the speed of 106Kbps.

• Review of KIISC
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• v.1 no.2
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• pp.9-28
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• 1991

창간호에 이어 본고에서는 동기축자암호시스템(synchronous stream ciphers)의 암호 화 및 복호, 키 자동키 암호시스템, 그리고 자기동조축자암호시스템의 암호문귀환암호시스 템과 평문귀환암호시스템에 관하여 분석하고자 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.17-24
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• 2009

Zhang et al. proposed a improved fast correlation attack on stream ciphers at SAC'08[8]. This attack is based on the fast correlation attack proposed at Crypto'00 and combined with FWT(fast Walsh transform). Given various attack environments, they presented complexities and success probabilities of the proposed attack algorithm. However, we found that our simulation results of the proposed attack algorithm are different from them presented in [8]. In this paper, we correct results of the proposed attack algorithm by analyzing it theoretically. And we propose a threshold of valid bias.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9C
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• pp.846-852
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• 2006

The ${\kappa}$-error linear complexity is a ky measure of the stability of the sequences used in the areas of communication systems, stream ciphers in cryptology and so on. This paper introduces an efficient algorithm to determine the ${\kappa}$-error linear complexity and the corresponding error vectors of $p^m$-periodic binary sequences, where : is a prime and 2 is a primitive root modulo $p^2$. We also give a new sense about the ${\kappa}$-error linear complexity in viewpoint of coding theory instead of cryptographic results. We present an efficient algorithm for decoding binary cyclic codes of length $p^m$ and derive key properties of the minimum distance of these codes.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.495-502
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• 2005

Cryptographic algorithm testing is performed to ensure that a specific algorithm implementation is implemented correctly and functions correctly. CMVP(Cryptographic Module Validation Program) of NIST in US is the well-known testing system that validates cryptographic modules to Federal Information Processing Standards (FIPS). There is no FIPS-approved stream cipher, and CMVP doesn't involve its validation testing procedure. In this paper we provide validation systems for three currently used light-weight stream ciphers: Bluetooth encryption algorithm E0, 3GPP encryption algorithm A5/3, and RC4 used for WEP and SSL/TLS Protocols. Moreover we describe our validation tools implemented by JAVA programing.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.310-324
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• 2015

The stream cipher Salsa20 and its reduced versions are among the fastest stream ciphers available today. However, Salsa20/7 is broken and Salsa20/12 is not as safe as before. Therefore, Salsa20 must completely perform all of the four rounds of encryption to achieve a good diffusion in order to resist the known attacks. In this paper, a new variant of Salsa20 that uses the chaos theory and that can achieve diffusion faster than the original Salsa20 is presented. The method has been tested and benchmarked with the original Salsa20 with a series of tests. Most of the tests show that the proposed chaotic Salsa of two rounds is faster than the original four rounds of Salsa20/4, but it offers the same diffusion level.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.191-197
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• 2002

In this paper, we propose a stream cipher using a cellular automata. For the security evaluation, we use the statistical tests suggested on the report of FIPS PUB 140-2 and additionally, we apply entropy test, linear complexity test and auto-correlation test which are popular statistical tests for the output sequences of stream ciphers.

• ETRI Journal
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• v.43 no.6
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• pp.1113-1129
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• 2021

Lightweight ciphers are increasingly employed in cryptography because of the high demand for secure data transmission in wireless sensor network, embedded devices, and Internet of Things. The PRESENT algorithm as an ultralightweight block cipher provides better solution for secure hardware cryptography with low power consumption and minimum resource. This study generates the key using key rotation and substitution method, which contains key rotation, key switching, and binary-coded decimal-based key generation used in image encryption. The key rotation and substitution-based PRESENT architecture is proposed to increase security level for data stream and randomness in cipher through providing high resistance to attacks. Lookup table is used to design the key scheduling module, thus reducing the area of architecture. Field-programmable gate array (FPGA) performances are evaluated for the proposed and conventional methods. In Virtex 6 device, the proposed key rotation and substitution PRESENT architecture occupied 72 lookup tables, 65 flip flops, and 35 slices which are comparably less to the existing architecture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.4
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• pp.53-60
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• 2007

In a known plaintext scenario, fast correlation attack is very powerful attack on stream ciphers. Most of fast correlation attacks consider the cryptographic problem as the suitable decoding problem. In this paper, we introduce advanced multi-pass fast correlation attack which is based on the fast correlation attack, which uses parity check equation and Fast Walsh Transform, proposed by Chose et al. and the Multi-pass fast correlation attack proposed by Zhang et al. We guess some bits of initial states of the target LFSR with the same method as previously proposed methods, but we can get one more bits at each passes and we will recover the initial states more efficiently.