• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.333-345
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• 2002

As computers and networks become popular, distributing information on the Internet is common in our daily life. Also, the explosion of the Internet, of wireless digital communication and data exchange on Internet has rapidly changed the way we connect with other people. But secure mail is gaining popularity abroad and domestically because of their nature of providing security. That is. It has been used a variety of fields such as general mail and e-mail for advertisement. But, As the data transmitted on network can be easily opened or forged with simple operations. Most of existing e-mail system don't have any security on the transmitted information. Thus, security mail system need to provide security including message encryption, content integrity, message origin authentication, and non-repudiation. In this paper, we design and implement secure mail system with secure key agreement algorithm, non-repudiation service, and encryption capability to provide services for certification of delivery and certification of content as well as the basic security services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.661-669
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• 2008

Nowadays, authentication is essential to identify the legal users in a network communication. Usually, there are few wars to achieve authentication over a publicly accessible network system in order to protect certain private data from the unauthorized users, ranging from simple ID/Password to Biometrics System. One of the most active areas in OTP(One Time Password) research today aims at exploiting OTP to provide authentication in the finance and security industry. OTP is usually discarded once it has been used. this prevents huge loophole of traditional authentication system which employs the same ID and Password every time. However this OTP system also has its weaknesses in surviving some attacks. this paper proposes an advanced OTP protocol using PingPong-128 without loop hole of pre-existing OTP.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.463-468
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• 2021

Although the IoT is showing explosive growth due to the development of technology and the spread of IoT devices and activation of services, serious security risks and financial damage are occurring due to the activities of various botnets. Therefore, it is important to accurately and quickly detect the activities of these botnets. As security in the IoT environment has characteristics that require operation with minimum processing performance and memory, in this paper, the minimum characteristics for detection are selected, and KNN (K-Nearest Neighbor), Naïve Bayes, Decision Tree, Random A comparative study was conducted on the performance of machine learning algorithms such as Forest to detect botnet activity. Experimental results using the Bot-IoT dataset showed that KNN can detect DDoS, DoS, and Reconnaissance attacks most effectively and efficiently among the applied machine learning algorithms.

• Convergence Security Journal
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• v.18 no.4
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• pp.45-52
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• 2018

As the era of the 4th Industrial Revolution has progressed and the information and communication technologies have developed dramatically, the cyber threats will gradually become more intelligent and sophisticated. Therefore, in order to take systematic and prompt action in case of an accident while preparing measures against the threat, the role of intelligence agency is important. However, Korea is having difficulty in responding to the threats due to the lack of support for the national cybersecurity bill or the amendment bill of the National Intelligence Service. In this paper, I examine the cybersecurity function of the intelligence agency, the recent debate trends, and implications for the role of intelligence agency in our current situation. And then I intend to suggest some measures such as concentration on information gathering and analysis, enhancement of cyber threat prediction and response capacity, and strengthening of legal basis as a way to establish the role of intelligence agency for reinforcement of cybersecurity performance system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.4
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• pp.21-35
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• 2007

In ad hoc networks, position-based routing schemes, that use geographical positions of nodes, have been proposed to efficiently route messages. In these routing schemes, the location service is one of the key elements that determines and effects security and efficiency of the protocol. In this paper, we define security threats of location service and propose a new quorum based location service protocol. In our proposed protocol, nodes register their public keys in other nodes during the initialization phase and these registered keys are used to verify locations of other nodes and the messages exchanged. In this paper, we prove that our protocol is robust against traditional attacks and new attacks that may occur due to the use of position-based routing. We also analyze the efficiency of our protocol using various simulations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.5
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• pp.27-38
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• 2007

One of the most important security issues of e-mail service is user privacy. Currently, various security protocols, like PGP(pretty Good Privacy), S/MIME(Secure/Multipurpose Internet Mail Extension), have been proposed. These protocols, however, do not provide forward secrecy. Recently, some security protocols that provide forward secrecy were proposed. But all of them require changes to the current e-mail infrastructure. Moreover, contrary to authors' intention, some of them do not actually provide perfect forward secrecy. In this paper, we propose a new practical e-mail security protocol. The proposed protocol provides perfect forward secrecy and uses a practical e-mail model that dose not require any changes to existing e-mail servers. It encrypts and authenticates messages efficiently using elliptic curve based signcryption scheme. In addition, we provide a way to send secure group e-mails.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.1
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• pp.11-21
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• 2008

Biometrics-based user authentication has several advantages over traditional password-based systems for standalone authentication applications. This is also true for new authentication architectures known as crypto-biometric systems, where cryptography and biometrics are merged to achieve high security and user convenience at the same time. Recently, a cryptographic construct, called fuzzy vault, has been proposed for crypto-biometric systems. This construct aims to secure critical data(e.g., secret key) with the fingerprint data in a way that only the authorized user can access the secret by providing the valid fingerprint, and some implementations results for fingerprint have been reported. However, the previous results had some limitation of the provided security due to the limited numbers of chaff data fer hiding real fingerprint data. In this paper, we propose an approach to provide both the automatic alignment of fingerprint data and higher security by using a 3D geometric hash table. Based on the experimental results, we confirm that the proposed approach of using the 3D geometric hash table with the idea of the fuzzy vault can perform the fingerprint verification securely even with more chaff data included.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.1
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• pp.125-133
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• 2009

Security of biometric data is particularly important as the compromise of the data will be permanent. To protect the biometric data, we need to store it in a non.invertible transformed version. Thus, even if the transformed version is compromised, its valid biometric data are securely remained. Fuzzy vault mechanism was proposed to provide cryptographic secure protection of critical data(e.g., encryption key) with the fingerprint data in a way that only the authorized user can access the critical data by providing the valid fingerprint. However, all the previous results cannot operate on the fingerprint image with a few minutiae, because they use fixed degree of the polynomial without considering the number of fingerprint minutiae. To solve this problem, we use adaptive degree of polynomial considering the number of minutiae. Also, we apply multiple polynomials to operate the fingerprint with a few minutiae. Based on the experimental results, we confirm that the proposed approach can enhance the security level and verification accuracy.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.49-59
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• 2002

As the electronic commerce increases rapidly in the mobile communication, security issues become more important. A suitable authentication and key agreement for the mobile communication environment is a essential condition. Some protocols based on the public key cryptosystem such as Diffie-Hellman, EIGamal etc. were adapted in the mobile communication. But these protocols that are based on the difficult mathematical problem in the algebra, are so slow and have long key-length. Therefore, these have many limitation to apply to the mobile communication. In this paper, we propose an authentication and key agreement protocol based on NTRU to overcome the restriction of the mobile communication environment such as limited sources. low computational fewer, and narrow bandwidth. The proposed protocol is faster than other protocols based on ECC, because of addition and shift operation with small numbers in the truncated polynomial ring. And it is as secure as other existent mathematical problem because it is based on finding the Shortest or Closest Vector Problem(SVP/CVP).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.183-188
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• 2011

According to increased multimedia data(i.e., MPEG video stream) in mobile application, protecting data becomes an important problem in the multimedia data delivery. SECMPEG is a selective encryption approach for protecting multimedia data. However, the computational overhead of SECMPEG's security level 3 is quite large because it encrypts the whole I-frames whose size is relatively larger than P/B-frames. Therefore, we need to analyze the characteristics of MPEG2 standard and derive an effective encryption of the I-frames. In this paper, we propose a slice-level, selective encryption approach by using the error-propagation characteristics of I-frames by a receiver. Our experimental results show that the proposed approach can reduce the execution time of SECMPEG's security level 3 by a factor of 30 without degradation of the security.