• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2660-2679
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• 2017

Crypton is a SP-network block cipher that attracts much attention because of its excellent performance on hardware. Based on Crypton, mCrypton is designed as a lightweight block cipher suitable for Internet of Things (IoT) and Radio Frequency Identification (RFID). The security of Crypton and mCrypton under meet-in-the-middle attack is analyzed in this paper. By analyzing the differential properties of cell permutation, several differential characteristics are introduced to construct generalized ${\delta}-sets$. With the usage of a generalized ${\delta}-set$ and differential enumeration technique, a 6-round meet-in-the-middle distinguisher is proposed to give the first meet-in-the-middle attack on 9-round Crypton-192 and some improvements on the cryptanalysis of 10-round Crypton-256 are given. Combined with the properties of nibble permutation and substitution, an improved meet-in-the-middle attack on 8-round mCrypton is proposed and the first complete attack on 9-round mCrypton-96 is proposed.

• 정보보호학회논문지
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• 제27권6호
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• pp.1261-1269
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• 2017

블록 암호 설계에서 Feistel 구조는 가장 널리 사용되는 구조 중의 하나이다. 또한 Feisel 구조를 확장하여 일반화한 Feistel 구조 역시 블록 암호 뿐 아니라 해쉬 함수에서도 널리 사용되는 구조이다. Feistel 구조의 구조적 안전성에 대한 다양한 분석 및 많은 연구가 진행되었다. 이 중 최근 Feistel 구조에 대한 중간 일치 공격은 Feistel 구조의 구조적 안전성을 가장 효과적으로 분석하는 방법 중 하나이다. 본 논문에서는 일반화된 Feistel 구조에 대한 중간 일치 공격에 대한 안전성을 분석한다.

• Journal of Communications and Networks
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• 제14권1호
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• pp.10-14
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• 2012

When tag privacy is required in radio frequency identification (ID) system, a reader needs to identify, and optionally authenticate, a multitude of tags without revealing their IDs. One approach for identification with lightweight tags is that each tag performs pseudo-random function with his unique embedded key. In this case, a reader (or a back-end server) needs to perform a brute-force search for each tag-reader interaction, whose cost gets larger when the number of tags increases. In this paper, we suggest a simple and efficient identification technique that reduces readers computation to $O$(${\sqrt{N}}$ log$N$) without increasing communication cost. Our technique is based on the well-known "meet-in-the-middle" strategy used in the past to attack symmetric ciphers.

• 가정과삶의질연구
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• 제16권2호
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• pp.83-96
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• 1998

The purpose of this study was to investigate the level of assets and liabilities of farm households and to evaluate the financial status of rural middle-aged and old-aged household using financial ratios. For these purposes an empirical survey data was gathered from rural middle-aged and old-aged households in 8 provinces using structured questionnaires. 877 households data were used in final analysis. The statistical methods used for data analysis are frequency percentile mean The statistical methods used for data analysis are frequency percentile mean median standard deviation $\chi$2 and t-test using SPSS/PC WIN program. Among financial ratios 64.7% of total households could meet the guideline of consumption to income ratio 5.9% of total households could meet the appropriate level of short-term and long-term liquidity. In the case of debt burden ration 82% of total households could meet the guideline. And 28.5% of total households could meet the guideline of capital stock ratio .

• 정보보호학회논문지
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• 제19권2호
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• pp.3-9
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• 2009

본 논문에서는 블록암호 분석기법인 중간 일치 분석법을 이용한 새로운 부채널 공격 방법을 소개한다. 이 공격 기법을 이용하여, 축소 마스킹을 사용하는 미연방 표준 블록암호 AES에 대한 부채널 공격을 소개한다. 즉, 10개 라운드에 축소 마스킹을 사용하는 AES는 기 제안된 4-라운드 중간 일치 함수에 기반한 부채널 공격에 취약함을 보인다. 이는 전체 12-라운드 192-비트 키 AES가 부채널 공격에 안전하기 위해서는 전체 12개의 라운드에 마스킹을 이용해야함을 나타낸다. 본 논문의 결과는 10개 라운드에 축소 마스킹을 사용하는 AES에 대한 첫 분석 결과이다.

• 디지털산업정보학회논문지
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• 제5권1호
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• pp.51-61
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• 2009

Conventional DES has been not only shown to have a vulnerable drawback to attack method called 'Meet in the Middle', but also to be hard to use that it is because software implementation has a number of problem in real time processing. This paper describes the design and implementation of the expanded DES algorithm using VHDL for resolving the above problems. The main reason for hardware design of an encryption algorithm is to ensure a security against cryptographic attack because there is no physical protection for the algorithm written in software. Total key length of 352 bits is used for the proposed DES. The result of simulation shows that the inputted plaintext in cryptosystem are equal to the outputted that in decryptosystem.

• 대한가정학회지
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• 제34권5호
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• pp.293-306
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• 1996

An educational program for parent caregiving families has been developed with a view to help mitigate burdens of those who provide caring services for their aged parents and to meet the needs of both the caregiving middle-aged daughter-in-law and the parent. The program has been applied to a small group of people who at least one living aged parent. The effectiveness of the program has been evaluated by taking pre- and posttests. The result of the tests strongly suggest that the program has been effective in improving participatns' knowledge on aging process, confict solving and relationship with parent.

• 한국식생활문화학회지
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• 제21권5호
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• pp.473-480
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• 2006

The purpose of this study were to investigate middle and high school students' food habits and food attitudes, and to assess student's nutrient consumption. A self-administered questionnaire was developed based on review of literature. The questionnaire consisted of three sections (food habits, food attitudes, and food consumption). The questionnaires were distributed to 4,050 students enrolled in 34 middle and high schools located in Seoul, Gyeonggi, and Gyeongnam provinces. A final response rate was 88.2% (3,570) excluding responses that had significant missing data. Data of the food habits and food attitudes were analyzed with descriptive analysis, $x^2$-test, and t-test using SPSS WIN(ver.11.0). The student's self-reported food consumption data was converted into nutrient consumption using conversion factor. Many middle and high school students skipped breakfast and/or dinner. Approximately 29% of the students did not eat vegetables and fruits. Scores of the middle school student's attitudes(19.1) towards foods were significantly higher than those of the high school student's attitudes(18.7)(p<.001). Student's nutrient intakes were estimated according to the student's self-reported food consumption data. The nutrient intakes were compared with DRIs(Dietary Reference Intakes: DRIs) for their age groups. The result of EAR(Estimated Average Requirement: EAR) cut-point method demonstrated 57.7% of middle school boys, 64.4% of middle school girls, 70.2% of high school boys, and 71.0% of high school girls did not meet EAR for Calcium. Additionally, it showed that 39.0% of middle school boys, 23.7% of middle school girls, 58.4% of high school boys, and 24.4% of high school girls did not consume EAR for Vitamin $B_1$. 25.7% of middle school boys did not meet EAR for Vitamin $B_2$, while 44.4% high school boys did not satisfy EAR for Vitamin $B_2$.

• Journal of information and communication convergence engineering
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• 제3권1호
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• pp.5-8
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• 2005

Dynamic cipher has the property that the key-size, the number of round, and the plaintext-size are scalable simultaneously. We present the method for designing secure Dynamic cipher against meet-in-the-middle attack and linear cryptanalysis. Also, we show that the differential cryptanalysis to Dynamic cipher is hard. In this paper we propose a new network called Dynamic network for symmetric block ciphers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권2호
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• pp.727-746
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• 2018

The hash function RIPEMD-160 is a worldwide ISO/IEC standard and the hash function HAS-160 is the Korean hash standard and is widely used in Korea. On the basis of differential meet-in-the-middle attack and biclique technique, a preimage attack on 34-step RIPEMD-160 with message padding and a pseudo-preimage attack on 71-step HAS-160 without message padding are proposed. The former is the first preimage attack from the first step, the latter increases the best pseudo-preimage attack from the first step by 5 steps. Furthermore, we locate the linear spaces in another message words and exchange the bicliques construction process and the mask vector search process. A preimage attack on 35-step RIPEMD-160 and a preimage attack on 71-step HAS-160 are presented. Both of the attacks are from the intermediate step and satisfy the message padding. They improve the best preimage attacks from the intermediate step on step-reduced RIPEMD-160 and HAS-160 by 4 and 3 steps respectively. As far as we know, they are the best preimage and pseudo-preimage attacks on step-reduced RIPEMD-160 and HAS-160 respectively in terms of number of steps.