• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.737-744
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• 2010

The use of RFID recently tends to increase and is expected to expand all over the industry and life. However, RFID is much vulnerable to the malign threats such as eavesdropping, replay attack, spoofing attack, location tracking in the process of authentication. In particular, it is difficult to apply authentication protocol used in the other previous system to low-priced RFID tag. After all, this paper suggests the scheme of efficient authentication protocol for RFID privacy protection. Compared to the previous scheme, suggested scheme reinforces the checking process of transmission data and is secure from eavesdropping and spoofing attack. It minimizes the operation work of the tag and is very useful to apply to the low-priced tag. It also has the merit to confirm the efficiency of communication by reducing the communication rounds.

• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.439-446
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• 2004

In the Internet, user authentication is the most important service in secure communications. Although password-based mechanism is the most widely used method of the user authentication in the network, people are used to choose easy-to-remember passwords, and thus suffers from some Innate weaknesses. Therefore, using a memorable password it vulnerable to the dictionary attacks. The techniques used to prevent dictionary attacks bring about a heavy computational workload. In this paper, we describe a recent solution, the Optimal Strong-Password Authentication (OSPA) protocol, and that it is vulnerable to the stolen-verifier attack and an impersonation attack. Then, we propose an Improved Optimal Strong-Password Authentication (I-OSPA) protocol, which is secure against stolen-verifier attack and impersonation attack. Also, since the cryptographic operations are computed by the processor in the smart card, the proposed I-OSPA needs relatively low computational workload and communicational workload for user.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.3
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• pp.220-228
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• 2001

Digital watermarking is a technique for the purpose of protecting the ownership of the image by embedding invisible watermarks in a digital imnge. To guarantee the security of the digital watermarking scheme for copyright protection, it is required to satisfy some requirements robustness and perceptual invisibility which provided by the location of embedded bits, the public watermarking algorithm, and the hidden use of the key, which can protect unauthorized accesses from illegal users. For this, in this paper we propose a new copyright watermarking scheme, which is based on one-way hash functions using RSA functions and modular operations. RSA functions are widely used in cryptographic systems. Our watermarking scheme is robust against LSB(Jeast significant bit) attacks and gamma corresction attack, and is also perceptually invisible. We demonstrate the characteristics of our proposed watermarking scheme through experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4814-4821
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• 2012

An e-passport is equipped with bio information by adding the non-attachable IC chip with a smart function. In order to solve such a problem, the user's privacy is protected by using the BAC, PA, AA and EAC mechanisms. However, the password key used in the BAC mechanism is made of the combination of the MRZ values. As a result, it is possible to decode the password by using the indiscriminate attacking program after finding out the combined rules of MRZ. This thesis suggests the mechanism with an improved level of efficiency through the time-stamp values by using the information of images and fingerprints and checking the forge or falsification of the e-passport when establishing a safe channel between the chip of the e-passport and the decoding system.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.607-611
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• 2008

This paper proposes new video signature using spatio-temporal information for copy detection. The proposed video copy detection method is based on concentric circle partitioning method for each key frame. Firstly, key frames are extracted from whole video using temporal bilinear interpolation periodically and each frame is partitioned as a shape of concentric circle. For the partitioned sub-regions, 4 feature distributions of average intensity, its difference, symmetric difference and circular difference distributions are obtained by using the relation between the sub-regions. Finally these feature distributions are converted into binary signature by using simple hash function and merged together. For the proposed video signature, the similarity distance is calculated by simple Hamming distance so that its matching speed is very fast. From experiment results, the proposed method shows high detection success ratio of average 97.4% for various modifications. Therefore it is expected that the proposed method can be utilized for video copy detection widely.

• Journal of Information Technology Services
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• v.19 no.1
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• pp.145-158
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• 2020

With the development and widespread application of online shopping, the number of online consumers has increased. With one click of a mouse, people can buy anything they want without going out and have it sent right to the doors. As consumers benefit from online shopping, people are becoming more concerned about protecting their privacy. In the group buying scenario described in our paper, online shopping was regarded as intra-group communication. To protect the sensitive information of consumers, the polynomial-based encryption key sharing method (Piao et al., 2013; Piao and Kim, 2018) can be applied to online shopping communication. In this paper, we analyze security problems by using a polynomial-based scheme in the following ways : First, in Kamal's attack, they said it does not provide perfect forward and backward secrecy when the members leave or join the group because the secret key can be broken in polynomial time. Second, for simultaneous equations, the leaving node will compute the new secret key if it can be confirmed that the updated new polynomial is recomputed. Third, using Newton's method, attackers can successively find better approximations to the roots of a function. Fourth, the Berlekamp Algorithm can factor polynomials over finite fields and solve the root of the polynomial. Fifth, for a brute-force attack, if the key size is small, brute force can be used to find the root of the polynomial, we need to make a key with appropriately large size to prevent brute force attacks. According to these analyses, we finally recommend the use of a relatively reasonable hash-based mechanism that solves all of the possible security problems and is the most suitable mechanism for our application. The study of adequate and suitable protective methods of consumer security will have academic significance and provide the practical implications.

• Journal of KIISE
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• v.41 no.11
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• pp.982-991
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• 2014

The integrity assurance of recorded video by car black boxes are necessary as the car black box is becoming more popular. In this paper, we propose a video data integrity assurance scheme reflecting the features of car black box. The proposed method can detect any kind of deletion, insertion, modification of frames by cyclic chaining using inter block relation. And, it provides the integrity assurance function consistently even in cases of file overwriting because of no more free space in storage, partial file data lost. And non-repudiation is supported. Experimental results with a car black box embedded system with A8 application processor show that our method has a feasible computational overhead to process full HD resolution video at 30 frames per second in a real time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1059-1070
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• 2018

The block cipher Zorro is designed to reduce the implementation cost for side-channel countermeasure. It has a structure similar to AES, but the number of S-Boxes used is small. However, since the master key is used as the round key, it can be vulnerable to related key attacks. In this paper, we show key recovery attacks on Zorro using related-key differential characteristics. In addition, the related key differential characteristics are fatal when Zorro is used as the base block cipher of the hash function. In this paper, we describe how these characteristics can be linked to collision attacks in the PGV models.

• The KIPS Transactions:PartA
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• v.14A no.5
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• pp.269-278
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• 2007

Caching in a cache sorrel cluster environment has an advantage that minimizes the request and response tine of internet traffic and web user. Then, one of the methods that increases the hit ratio of cache is using the hash function with cooperative caching. It is keeping a fixed size of the total cache memory regardless of the number of cache servers. On the contrary, if there is no cooperative caching, the total size of cache memory increases proportional to the number of cache sowers since each cache server should keep all the cache data. The disadvantage of hashing method is that clients' requests stress a few servers in all the cache servers due to the characteristics of hashing md the overall performance of a cache server cluster depends on a few servers. In this paper, we propose the method that distributes uniformly client requests between cache servers using dynamic server information. We performed experiments using 16 PCs. Experimental results show the uniform distribution o

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3708-3714
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• 2009

Recently, most of information services are provided by the computer network, since the technology of computer communication is developing rapidly, and the worth of information over the network is also increasing with expensive cost. But various attacks to quietly intercept the informations is invoked with the technology of communication developed, and then most of the financial agency currently have used OTP, which is generated by a token at a number whenever a user authenticates to a server, rather than general static password for some services. A 2-factor OTP generating method using the OTP token is mostly used by the financial agency. However, the method is vulnerable to real attacks and therefore the OTP token could be robbed and disappeared. In this paper, we propose a 3-factor OTP way using HMAC to conquer the problems and analyze the security of the proposed scheme.