• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.592-598
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• 2010

A home network system is made up of subject of cyber attack from a variety factors of threatening, but also have security weakness in cases of hacking, vicious code, worm virus, DoS attack, tapping of communication network, and more. So, the necessity for a security protocol to protect user asset and personal information within a home network is gradually increasing. Thus, this paper designs and suggests a home network security protocol using user authentication and approach-control technology to prevent the threat by unauthorized users towards personal information and user asset in advance by providing the gradual authority to corresponding devices based on authorized information, after authorizing the users with a Public Key Certificate.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.107-115
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• 2004

SHACAL-2 is a 256 bit block cipher with various key sizes based on the hash function SHA-2. Recently, it was recommended as one of the NESSIE selections. UP to now, no security flaws have been found in SHACAL-2. In this paper, we discuss the security of SHACAL-2 against an impossible differential attack. We propose two types of 14 round impossible characteristics and using them we attack 30 round SHACAL-2 with 512 bit 18y. This attack requires 744 chosen plaintexs and has time complexity of 2$^{495.1}$ 30 round SHACAL-2 encryptions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.3-13
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• 2004

Kvarnstrom et al. ${in}^{[10]}$ proposed a rule protection scheme by using one-way hash function to protect rules in security systems over ubiquitous environment. Son et at. ${in}^{[5-6]}$ also prooposed a rule protection scheme for Snort, which is one of the most common IDS. These schemes provide security only for the header information but not for its contents. To solve this problem, this paper presents a scheme based on the symmetric cryptosystem over Snort not only for the header information but also contents. This paper uses the key management based on PCMCIA security module proposed ${by}^{[12]}$ for the symmetric cryptosystem. Our scheme could be adjusted to other security systems, which use the rule based detection.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.57-66
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• 2005

SHACAL-2 is a 256-bit block cipher with various key sizes based on the hash function SHA-2. Recently, it was recommended as one of the NESSIE selections. This paper presents differential-linear type attacks on SHACAL-2 with 512-bit keys up to 32 out of its 64 rounds. Our 32-round attack on the 512-bit keys variants is the best efficient attack on this cipher in published literatures.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.259-264
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• 2014

Body insertion due to the recent development of sensor technology, the device is attached patients to receive medical services from anywhere, anytime environment is changing. Body insertion devices for the hospital, the patient's vital information attached personnel (doctors, nurses, pharmacists, etc.) to pass, however, when a problem occurs, a patient's information to a third party that can be exploited easily exposed. In this paper, we proposed signature authentication protocols mandate based on the patient's power of attorney from the center of the u-Healthcare services, hospital officials FormHelper third party disguised as a patient, the hospital patient information easily obtained from the officials to prevent. The proposed protocol, the patient's sensitive information to a third party, do not expose the patient's sensitive information to the random number generated by the u-Healthcare service centers and patients hash signature key to encrypt sensitive information of patients. From third parties to maintain synchronization between the patients and the hospital personnel in order to prevent patient information from being exploited illegally by the patient's vital information leakage can be prevented.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.1
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• pp.19-24
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• 2007

Abstract. In the ubiquitous environment of the next generation, RFID is predicted to occupy an important technical location and also expected to apply to various fields. However, the properties of tags in itself which is the core of RFID have a dysfunction like an invasion of privacy for user. An existing cryptanalytic protection scheme of the information leakage have a difficult problem to apply to RFID tags for privacy protection. We applied Ohkubo et al.'s scheme to the protection of the tag's information efficiently in the RFID system environment using low-cost tags. But, this method has all informations of tagsto identify tag's ID and then performs the process of identification in sequence in the Back-end server. These processes have lots of computations so that it have problems about a scalability. In this paper, we are based on Ohkubo et al.'s scheme to solve problems, and then analyze the parallelism with the Hellman's tradeoff method, divide it into nodesin parallel. In this paper, we are based on Okubo et al.'s scheme to solve problems, and then analyze the parallelism with Hellman's tradeoff method, divide it into the ${\omega}$ node in parallel. as a result, we can reduce the computing complexity of key search to $O(\frac{m^{2/3}n^{2/3}}{\omega})$ seconds from O(mm) seconds. finally we show the results to be enhanced the scalability.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.32-43
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• 2010

IPTV is an emerging technology that combines both broadcasting and tele-communication technologies, and provides various multi-media contents to the service subscribers. In general, IPTV broadcasters transmit scrambled signals (multi-media contents) to the paying subscribers, and the users within the acknowledged network descramble the signals using the smart-card. That is, users are verified through communication between STB (Set-Top Box) and smart-card. In 2004, Jiang et al. proposed a secure protocol regarding the verification process. The method has been modified and enhanced by several following research works. However, all the methods that have been proposed so far required modular exponentiation operations which may raise the smart-card costs. In this paper, we propose a new efficient mutual authentication and session-key establishment protocol using only hash functions and exclusive-or operations, and show that the proposed protocol is still secure under various security attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.651-657
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• 2006

This paper propose the technique for the execution authentication of digital signature with TTS(traceable trust server) to guarantee the safe execution of mobile agents. That is to say, it is focused on improving the processing speed of systems and the traffic of network which are problems in the existing studies. The digital signature is used to guarantee the efficient and safe execution and the integrity of mobile agents. The certificate of it is chained with synthesis function, cryptographic algorithm based on public key, and hash function. And white hosts can be protected against the threat of being used maliciously. Then, we prove the efficiency of system overhead and the traffic of network by the analysis. In case the certificate chain of a digital signature is used, the safe execution of mobile agents can be protected against attackers that wish to insert a newly created certificate after cutting off the chain after striking space key 2 times.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.61-68
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• 2011

Recently arithmetic circuit of lightweight AES symmetric key algorithm that can apply to passive tag have been developed, then security protocol of RFID system using AES symmetric encryption techniques have been proposed. This paper proposed security enhancement protocol of RFID system using lightweight AES arithmetic circuit and random number generator of passive tag. The proposed protocol have AES algorithm and random number generator at server, reader, tag, and transmit encrypted message by separate secret key using random number at each session. The mutual authentication of tag and reader used reader random number and tag random number. As a result, proposal protocol reduce authentication steps of the existing mutual authentication protocol, and reduce amount of computation of tag, and demonstrate as secure protocol to every attack type of attacker by decrease communication step of Air Zone.