• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.118-124
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• 2004

KASUMI is a 64-bit iterated block cipher with a 128-bit key size and 8 rounds Feistel structure. In this paper, we describe saturation attacks on the five round KASUMI, which requires 10 $\times$$2^{32}$ chosen plaintexts and $2^{115}$ computational complexity We also improve this attack using meet-in-the-middle technique. This attack requires 7$\times$$2^{32}$ chosen plaintexts and $2^{90}$ computational complexity. Futhermore, we attack KASUMI by controlling the value of the fixed part of the key. This attack needs 3$\times$$2^{32}$ chosen plaintexts and $2^{57}$ computational complexity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.1
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• pp.121-125
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• 2007

Differential cryptanalysis and linear cryptanalysis are the most powerful approaches known for attacking many block ciphers and used to evaluating the security of many block ciphers. So designers have designed secure block ciphers against these cryptanalyses. In this paper, we present new three block cipher structures. And for given r, we prove that differential(linear) probabilities for r-round blockcipher structures are upper bounded by $p^2(q^2),\;2p^2(2q^2)$ if the maximum differential(linear) probability is p(q) and the round function is a bijective function.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.15-29
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• 2014

Increasing the smart instrument based social and economical activity, problems of electronic business's safety, reliability and user's privacy are be on the rise. so variety standard cryptography algorithms for information security have been developed in korea and How to efficiently implement them in a variety of environments is issued. ARIA and SEED, developed in Korea, are standard block cipher algorithm to encrypt the 128-bit plaintext, are each configured Feistel, SPN structure. In this paper, SEED and ARIA were implemented using the GEZEL language that can be used easily in the software designer because grammar is simple compared to other hardware description language. In particular, in this paper, will be described in detail the characteristics and design method using GEZEL as the first paper that implements 128bits ARIA and SEED and it showed the flexibility and efficiency of development using GEZEL. SEED designed GEZEL is occupied 69043 slice, is operating Maximum frequency 146.25Mhz and ARIA is occupied 7282 slice, is operating Maximum frequency 286.172Mhz. Also, Speed of SEED designed and implemented signal flow method is improved 296%.

• Journal of the Korea Computer Industry Society
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• v.10 no.4
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• pp.167-176
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• 2009

In this paper, we propose an improved SHACAL-1 of the same encryption and decryption with a simple symmetric layer. SHACAL-1 has 4 rounds, and each round has 20 steps. Decryption is becoming inverse function of encryption, In this paper, we proposed SHACAL-1 are composed of the first half, symmetry layer and the last half. The first half with SHACAL-1 encryption algorithm 1 round does with 10 steps and composes of 4 round. The last half identically with SHACAL-1 decryption algorithm, has a structure. On the center inserts a symmetry layer, encryption and decryption algorithm identically, composes. In the experiments, the proposed SHACAL-1 algorithm showed similar execution time to that of the SHACAL-1. Thanks to the symmetric layer, the proposed algorithm makes it difficult for the attacks which take advantages of high probability path such as the linear cryptanalysis, differential cryptanalysis. The proposed algorithm can be applicable to the other block cipher algorithms which have different encryption and decryption and useful for designing a new block cipher algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.103-108
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• 2016

With the growing trend of pervasive computing, (the idea that technology is moving beyond personal computers to everyday devices) there is a growing demand for lightweight ciphers to safeguard data in a network that is always available. For all block cipher applications, the AES is the preferred choice. However, devices used in pervasive computing have extremely constraint environment and as such the AES will not be suitable. In this paper we design and implement a new lightweight compact block cipher that takes advantage of both S-P network and the Feistel structure. The cipher uses the S-box of PRESENT algorithm and a key dependent one stage omega permutation network is used as the cipher's P-box. The cipher is implemented on iNEXT-V6 board equipped with virtex-6 FPGA. The design synthesized to 196 slices at 337 MHz maximum clock frequency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4727-4741
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• 2019

The lightweight block cipher Piccolo adopts Generalized Feistel Network structure with 64 bits of block size. Its key supports 80 bits or 128 bits, expressed by Piccolo-80 or Piccolo-128, respectively. In this paper, we exploit the security of reduced version of Piccolo from the first round with the pre-whitening layer, which shows the vulnerability of original Piccolo. As a matter of fact, we first study some linear relations among the round subkeys and the properties of linear layer. Based on them, we evaluate the security of Piccolo-80/128 against the meet-in-the-middle attack. Finally, we attack 13 rounds of Piccolo-80 by applying a 5-round distinguisher, which requires $2^{44}$ chosen plaintexts, $2^{67.39}$ encryptions and $2^{64.91}$ blocks, respectively. Moreover, we also attack 17 rounds of Piccolo-128 by using a 7-round distinguisher, which requires $2^{44}$ chosen plaintexts, $2^{126}$ encryptions and $2^{125.49}$ blocks, respectively. Compared with the previous cryptanalytic results, our results are the currently best ones if considering Piccolo from the first round with the pre-whitening layer.