• Journal of KIISE:Computer Systems and Theory
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• v.32 no.3
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• pp.115-124
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• 2005

When the application code is downloaded into the mobile device, it is important to provide authentication. Usually, mobile code execution is overlapped with downloading to reduce transfer delay. To the best of our knowledge, there has not been any algorithm to authenticate the mobile code in this environment. In this paper, we present two efficient code authentication schemes that permit overlapping of execution and downloading under the two cases: the first is when the order of transmission of code chunks is determined before the transmission and the second is when this order is determined during the transmission. The proposed methods are based on hash chaining and authentication trees, respectively. Especially, the latter scheme utilizes previously received authentication informations to verify the currently received chunk, which reduces both communication overhead and verification delay. When the application code consists of n chunks, communication overheads of the both schemes are 0(n) and verification delays of these two schemes are O(1) and O(log n), respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2029-2036
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• 2015

Hadoop MR(MapReduce) uses a partition function for passing the outputs of mappers to reducers. The partition function determines target reducers after calculating the hash-value from the key and performing mod-operation by reducer number. The legacy partition function doesn't divide the job effectively because it is so sensitive to key distribution. If the job isn't divided effectively then it can effect the total processing time of the job because some reducers need more time to process. This paper proposes the VPT(Virtual Partition Table) and has tested appling the VPT with a preponderance of data. The applied VPT improved three seconds on average and we figure it will improve more when data is increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.68-75
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• 2013

Recently IPTV that transmits multimedia contents in real time through internet, cable TV net and satelite net gets the limelight. But IPTV service that gives service to users by various media has a problem of not supporting user certification fully. This paper suggests a certification model which prevents getting access permission of IPTV service by sending illegal certification information by adolescent through integrating mobile communication technique with RFID(Radio Frequency IDentification) technique which is a key technique of Ubiquitous environment. This model performs the process of adult certification by keeping synchronization with user's certificaiton information that is saved in data-base of certification server and contents server after getting the system of class categorization in contents server to overcome disadvantage of simple adult certification system that is popular in the existing internet. Also, it adapts double hash chain technique not to down load illegally contents without the permission of manager even if an adolescent gets manager's approval key.

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.623-630
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• 2007

With the development in IT technology and with growing demands of users, a ubiquitous environment is being made. Because of individuals identification is important in ubiquitous environment, RFID, a technology used frequently. RFID, a technology that radio frequency identification, reader send signer, then tag provide user information. RFID has various strengths, such as high recognition rates, quick recognition speed, but Eavesdropping is possible and problem that user information is revealed happens. To solve this, study is proceeded with activity, but, because of low-cost passive tag is limited operation capability, usually used hash function and random number. Also updates value that is used to present session and uses in next session. Therefore, this scheme protects user privacy using random number. And this sheme can offer synchronization by creating variable value without updating value.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1099-1108
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• 2009

The study of IP address allocation in MANET can be categories into Stateful and Stateless. The one, special node monitors other nodes' IP address and allocates IF address. And the other, node generates IP address by itself. Nodes in MANET have mobility and restricted resource, so Stateless is more suitable than Stateful. But, in Stateless, node requires DAD process because of unique IP address allocation. And Dos attack can be happened in DAD precess. In this paper, we propose a security method on preventing DoS attack against DAD in MANET using one-way hash function. Since, Computation of one-way hash function is suitable for nodes' restricted resource character in MANET. And we evaluate performance using NS2 and compare with other security method which is CGA using signature.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1367-1372
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• 2007

This paper suggests One-time Password key exchange authentication technique for a strong authentication based on MANET and through identify wireless environment security vulnerabilities, analyzes current authentication techniques. The suggested authentication technique consists of 3 steps: Routing, Registration, and Running. The Routing step sets a safe route using AODV protocol. The Registration and Running step apply the One-time password S/key and the DH-EKE based on the password, for source node authentication. In setting the Session key for safe packet transmission and data encryption, the suggested authentication technique encrypts message as H(pwd) verifiers, performs key exchange and utilizes One time password for the password possession verification and the efficiency enhancement. EKE sets end to end session key using the DH-EKE in which it expounds the identifier to hash function with the modula exponent. A safe session key exchange is possible through encryption of the H(pwd) verifier. The suggested authentication technique requires exponentiation and is applicable in the wireless network environment because it transmits data at a time for key sharing, which proves it is a strong and reliable authentication technique based on the complete MANET.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.697-708
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• 2019

In this paper, we propose and implement a method to optimize Rainbow for 8 bit MCU(Microcontroller Unit). As quantum computers have been developed, the security of existing cryptography, especially the signature algorithms, has been threatened, so it is necessary to apply a signature scheme with a quantum-resistance to IoT devices. Currently, the proposed PQC(Post Quantum Cryptography) are lattice-based, hash-based, code-based, and MQ(Multivariate Quadratic)-based cryptographic algorithms and signature schemes. In particular, MQ-based signature schemes are faster than conventional signature schemes and are suitable for IoT devices Do. However, it is difficult to apply 8-bit MCU, which has a large key length and large number of computations, to the memory and performance of IoT devices. In this paper, we propose a method of storing Rainbow, which is a MQ-based signing scheme, in 8-bit MCU by dividing the key and optimizing the computation method. By reducing the memory consumption and improving the algorithm speedily, Compare performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.6 no.4
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• pp.67-84
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• 1996

VDL-SL (Vienna Development Method-Specification Language) is one of the FSL(Formal Specification Language) which is being presented for the correct description of the security relevant standards. Several tools are being developed for the correctness and the convenience in the description and executable code generation of security relevant standards using VDM-SL. The IFAD VDM-SL Toolbox is one that has many functions : syntax checking, type checking, c++ code generation, test coverage information. This paper describes a formal method for description and implementation of MD4 algorithm using VDM-SL and IFAD VDM-SL Toolbox, and examines the result applied to secure hash algorithm, and proposes the relation to strict conformance test which recently suggested as a security test method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.53-64
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• 2005

Previous secure routing protocols for wireless sensor networks assume that a sink is static. In many cases, however, a sink operated by man or vehicle is moving. A mobile sink creates a lot of technical problems such as reconfiguration of routing path exposure of sink location. and selection of secure access point node, which are not considered by many previous researches. In this paper, we propose a new secure routing scheme for solving such problems using hi-directional hash chain and delegation nodes of grid structure. This scheme provides a secure routing path and prevents attacker from recognizing the location of a mobile sink in sensor networks. This new method reduces the resource requirements compared to the cashed routing schemes. Simulation results also show that the system is secure and efficient enough.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.3
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• pp.115-126
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• 2005

SHACAL-2 is a 256-bit block cipher with up to 512 bits of key length based on the hash function SHA-2. It was submitted to the the NESSIE project and was recommended as one of the NESSIE selections. In this paper, we present two types of related-key attacks called the related-key differential-(non)linear and the related-key rectangle attacks, and we discuss the security of SHACAL-2 against these two types of attacks. Using the related-key differential-nonlinear attack, we can break SHACAL-2 with 512-bit keys up to 35 out of its 64 rounds, and using the related-key rectangle attack, we can break SHACAL-2 with 512-bit keys up to 37 rounds.