• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5639-5653
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• 2016

Security models for key exchange protocols have been researched for years, however, lots of them only focus on what secret can be compromised but they do not differentiate the timing of secrets compromise, such as the extended Canetti-Krawczyk (eCK) model. In this paper, we propose a new security model for key exchange protocols which can not only consider what keys can be compromised as well as when they are compromised. The proposed security model is important to the security proof of the key exchange protocols with forward secrecy (either weak forward secrecy (wFS) or strong forward secrecy (sFS)). In addition, a new kind of key compromise impersonation (KCI) attacks which is called strong key compromise impersonation (sKCI) attack is proposed. Finally, we provide a new one-round key exchange protocol called mOT+ based on mOT protocol. The security of the mOT+ is given in the new model. It can provide the properties of sKCI-resilience and sFS and it is secure even if the ephemeral key reveal query is considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1687-1707
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• 2022

With the development of multiuser online meetings, more group-oriented technologies and applications for instance collaborative work are becoming increasingly important. Authenticated Group Key Agreement (AGKA) schemes provide a shared group key for users with after their identities are confirmed to guarantee the confidentiality and integrity of group communications. On the basis of the Public Key Cryptography (PKC) system used, AGKA can be classified as Public Key Infrastructure-based, Identity-based, and Certificateless. Because the latter type can solve the certificate management overhead and the key escrow problems of the first two types, Certificateless-AGKA (CL-AGKA) protocols have become a popular area of research. However, most CL-AGKA protocols are vulnerable to Public Key Replacement Attacks (PKRA) due to the lack of public key authentication. In the present work, we present a CL-AGKA scheme that can resist PKRA in order to solve impersonation attacks caused by those attacks. Beyond security, improving scheme efficiency is another direction for AGKA research. To reduce the communication and computation cost, we present a scheme with only one round of information interaction and construct a CL-AGKA scheme replacing the bilinear pairing with elliptic curve cryptography. Therefore, our scheme has good applicability to communication environments with limited bandwidth and computing capabilities.

• 정보처리학회논문지A
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• 제13A권7호
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• pp.615-622
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• 2006

무선 인터넷 프록시 서버 클러스터 환경에서의 캐싱은 인터넷 트래픽, 웹 유저의 요청 및 응답 시간을 줄여주는 효과를 가진다. 이때, 캐시의 히트율(Hit ratio)을 증가시키는 한 가지 방법은 해쉬 함수를 이용하여 동일 요청 URL을 동일 캐시에 할당하는 방법이다. 해싱을 이용한 방법의 문제점은 해쉬의 특성으로 인해 클라이언트의 요청이 일부 캐시 서버로 집중되고 전체 시스템의 성능이 일부 캐시 서버에 종속된다는 점이다. 이에 본 논문에서는 해싱과 라운드 로빈 방식의 장점을 결합하여 클라이언트의 요청을 일부 캐시 서버가 아닌 전체 캐시 서버에 균일하게 분포시키는 개선된 부하 분산 방법을 제안한다. 기존 해싱 방법에서는 요청 URL에 대한 해쉬값이 계산되면 캐시 서버가 컴파일 시간에 정적으로 할당되는 반면, 제안된 방법에서는 라운드 로빈 방법을 사용하여 실행 시간에 동적으로 할당된다. 제안된 방법은 무선 인터넷 프록시 서버 클러스터 환경에서 구현되었고, 16대의 컴퓨터를 이용하여 실험을 수행하였다. 실험 결과는 기존 해싱 방법에 비해 클라이언트의 요청을 캐시 서버들 사이로 균일하게 분포시키고, 이에 따라 전체 무선 인터넷 프록시 서버의 성능이 52%에서 112%까지 향상됨을 확인하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.234-235
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• 2016

With the development of the Internet, the popularization of internet has become the new trend and enormously changed the way of human communication. There is a strong need for security. The following research will provide the definition and purpose of IoT and examine its security concerns, In this paper, we surveyed at energy consumption of lightweight block ciphers implemented in reconfigurable devices, and we analyze d the effects that round unrolling might have on the energy consumed during the encryption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권9호
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• pp.3663-3679
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• 2020

Scheduling plays a dynamic role in cloud computing in generating as well as in efficient distribution of the resources of each task. The principle goal of scheduling is to limit resource starvation and to guarantee fairness among the parties using the resources. The demand for resources fluctuates dynamically hence the prearranging of resources is a challenging task. Many task-scheduling approaches have been used in the cloud-computing environment. Security in cloud computing environment is one of the core issue in distributed computing. We have designed a deep learning-based security model for scheduling tasks in cloud computing and it has been implemented using CloudSim 3.0 simulator written in Java and verification of the results from different perspectives, such as response time with and without security factors, makespan, cost, CPU utilization, I/O utilization, Memory utilization, and execution time is compared with Round Robin (RR) and Waited Round Robin (WRR) algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.509-521
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• 2013

Impossible Differential Cryptanalysis (IDC) uses impossible differentials to discard wrong subkeys for the first or the last several rounds of block ciphers. Thus, the security of a block cipher against IDC can be evaluated by impossible differentials. This paper studies impossible differentials for Rijndael-like and 3D-like ciphers, we introduce methods to find 4-round impossible differentials of Rijndael-like ciphers and 6-round impossible differentials of 3D-like ciphers. Using our methods, various new impossible differentials of Rijndael and 3D could be searched out.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4548-4559
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• 2018

Conditional differential attack against NFSR-based cryptosystems proposed by Knellwolf et al. in Asiacrypt 2010 has been widely used for analyzing round-reduced Grain v1. In this paper, we present improved conditional differential attacks on Grain v1 based on a factorization simplification method, which makes it possible to obtain the expressions of internal states in more rounds and analyze the expressions more precisely. Following a condition-imposing strategy that saves more IV bits, Sarkar's distinguishing attack on Grain v1 of 106 rounds is improved to a key recovery attack. Moreover, we show new distinguishing attack and key recovery attack on Grain v1 of 107 rounds with lower complexity O($2^{34}$) and appreciable theoretical success probability 93.7%. Most importantly, our attacks can practically recover key expressions with higher success probability than theoretical results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4060-4075
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• 2019

ACORN is an authenticated encryption algorithm proposed as a candidate in the currently ongoing CAESAR competition. ACORN has a good performance on security and efficiency which has been a third-round candidate. This paper mainly concentrates on the security of ACORN under the forgery attack and the non-repudiation of ACORN. Firstly, we analyze the differential properties of the feedback function in ACRON are analyzed. By taking advantage of these properties, the forgery attacks on round-reduced ACORN are proposed with a success probability higher than $2^{-128}$ when the number of finalization rounds is less than 87. Moreover, the non-repudiation of ACRON in the nonce-reuse setting is analyzed. The known collision can be used to deny the authenticated message with probability $2^{-120}$. This paper demonstrates that ACORN cannot generate the non-repudiation completely. We believe it is an undesirable property indeed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권3호
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• pp.972-985
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• 2022

In the year 2020, a new lightweight block cipher µ² is proposed. It has both good software and hardware performance, and it is especially suitable for constrained resource environment. However, the security evaluation on µ² against impossible differential cryptanalysis seems missing from the specification. To fill this gap, an impossible differential cryptanalysis on µ² is proposed. In this paper, firstly, some cryptographic properties on µ² are proposed. Then several longest 7-round impossible differential distinguishers are constructed. Finally, an impossible differential cryptanalysis on µ² reduced to 10 rounds is proposed based on the constructed distinguishers. The time complexity for the attack is about 2^69.63 10-round µ² encryptions, the data complexity is O(2⁴⁸), and the memory complexity is 2^63.57 Bytes. The reported result indicates that µ² reduced to 10 rounds can't resist against impossible differential cryptanalysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권2호
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• pp.478-493
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• 2024

In this paper, the Mixed Integer Linear Programming (MILP) model is improved for searching differential characteristics of block cipher Midori-64, and 4 search strategies of differential path are given. By using strategy IV, set 1 S-box on the top of the distinguisher to be active, and set 3 S-boxes at the bottom to be active and the difference to be the same, then we obtain a 5-round differential characteristics. Based on the distinguisher, we attack 12-round Midori-64 with data and time complexities of 2⁶³ and 2^103.83, respectively. To our best knowledge, these results are superior to current ones.