• KNOM Review
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• v.22 no.2
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• pp.39-47
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• 2019

There are several big data-driven advanced research activities such as meteorological climate information, high energy physics, astronomy research, satellite information data, and genomic research data on KREONET. Since the performance degradation occurs in the environment with the existing network security equipment, methods for preventing the performance degradation on the high-performance research-only network and for high-speed research collaboration are being studied. In addition, the recent issue of quantum computers has been a threat to security using the existing encryption system. In this paper, we construct quantum cryptography-based communication network through environment construction and high-performance transmission test that build physical security through quantum cryptography-based communication network in end-to-end high-speed research network. The purpose of this study is to analyze the effect on network performance when performing physical encryption and to use it as basic data for constructing high-performance research collaboration network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.1064-1079
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• 2019

Information security has become increasingly important with the rapid development of mobile devices and internet. An efficient encryption system is a key to this end. In this paper, we propose an image encryption method based on the cross diffusion of two chaotic maps. We use two chaotic sequences, namely the Logistic map and the Chebyshev map, for key generation which has larger security key space than single one. Moreover, we use these two sequences for further image encryption diffusion which decreases the correlation of neighboring pixels significantly. We conduct extensive experiments on several well-known images like Lena, Baboon, Koala, etc. Experimental results show that our algorithm has the characteristics of large key space, fast, robust to statistic attack, etc.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.1
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• pp.41-46
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• 2008

With widespread use of the Internet and improvements in streaming media and compression technology, digital music, video, and image can be distributed instantaneously across the Internet to end-users. However, most conventional Digital Right Management are often not secure and fast enough to process the vast amount of data generated by the multimedia applications to meet the real-time constraints. In this paper, we propose the copyright protection using encryption of DCT coefficients and motion vector in MPEG-4 video codec of mobile device. This paper presents a new Digital Rights Management that modifies the Motion Vector of Macroblock for mobile device. Experimental results indicate that the proposed DRM can not only achieve very low cost of the encryption but also enable separable authentication to individual mobile devices such as Portable Multimedia Player and Personal Digital Assistants. The performance of the proposed methods have low complexity and low increase of bit rate in overhead.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.87-96
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• 2013

In this paper, we suggest redesigned RTP protocol that is able to perform encryption of VoIP media information for single private network and between the different private networks. And we conduct a test for performance analysis. Such as SRTP or ZRTP methods have been used for VoIP media encryption. But, the existing encryption techniques have problem that can not perform end-to-end encryption between different private networks. In order to solve this problem, in this paper, we redesign RTP protocol. Redesigned RTP includes all information for encryption of VoIP media. Therefore the encryption is not affected by modification of SIP and SDP information that occurred in gateway. Also, redesigned RTP includes code for whether or not to apply encryption. By using the code, modification of RTP header from gateway prevents. As a result, redesigned RTP maintain the integrity and the RTP is able to perform encryption between the different private networks. Also, we conduct a test for performance analysis of SRTP, ZRTP and redesigned RTP.

• Journal of Information Technology Applications and Management
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• v.11 no.4
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• pp.25-33
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• 2004

Recently, as network and computer technologies are growing rapidly, most of business transactions are performed in cyber world. In spite of many advantages, the most concerns in Electronic Commerce are the information security matters, and the cryptosystem has been claimed as one of the proper means to settle this problem. In this paper, a partial encryption/decryption algorithm has been in-troduced to show the efficiency against the conventional method in which all the data are completely encoded. In our proposed scheme, the multimedia data can be efficiently encoded in a short time providing good data security. For example, the MP3 data can be securely protected with 10% encryption in our scheme. Moreover, 1he shuffling process at the end of partial encryption procedure provides higher level of data security.

• Journal of the Korea Society of Computer and Information
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• v.22 no.8
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• pp.63-72
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• 2017

In this paper, we propose a security architecture for HDLC-based T4 class common data link. The common data links are composed of point-to-point, multi-to-point, and point-to-multi mode. For multi-to-point mode, one node has a bundle of point-to-point links with different end-point on the other side of the links. Thus multi-to-point mode can be considered as a bundle of point-to-point mode. Point-to-multi mode is broadcasting link. For point-to-point mode we adopted robust security network scheme to establish a secure data link, and for multi-to-point mode we use broadcast encryption scheme based on ID-based cryptography to distribute encryption key for broadcasting message encryption. We also included MACsec technology for point-to-point data link security. Computational and communicational complexity analysis on the broadcast encryption have been done.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.13-29
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• 2003

Web-mail system is worthy of note as a next generation e-mail system for its mobility and easiness. But many web-mail system does not have any kind of security mechanism. Even if web-mail system provides security services, its degree of strength is too low. Using these web-mail systems, the e-mail is tabbed, modified or forged by attacker easily. To solve these problems, we design and implement secure web-mail system based on the international e-mail security standard S/MIME in this thesis. This secure web-mail system is composed of server system and client system The server system performs basic mail functions - sending/receiving the mails, storing the mails, and management of user information, etc. And the client system performs cryptographic functions - encryption/decryption of the mails, digital signing and validation, etc. Because client system performs cryptographic functions this secure web-mail system gives its reliability and safety, and provides end-to-end security between mail users. Also, this secure web-mail system increase system efficiency by minimize server load.

• Journal of Platform Technology
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• v.6 no.4
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• pp.69-77
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• 2018

In the case of personal information files containing personal information, there is insufficient awareness of personal information protection in end-point areas such as personal computers, smart terminals, and personal storage devices. In this study, we use Diffie-Hellman method to securely retrieve personal information files generated by web crawler. We designed SEED and ARIA using hybrid slicing to protect against attack on personal information file. The encryption performance of the personal information file collected by the Web crawling method is compared with the encryption decryption rate according to the key generation and the encryption decryption sharing according to the user key level. The simulation was performed on the personal information file delivered to the external agency transmission process. As a result, we compared the performance of existing methods and found that the detection rate is improved by 4.64 times and the information protection rate is improved by 18.3%.

• Journal of Communications and Networks
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• v.10 no.1
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• pp.18-27
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• 2008

This paper is to study a subclass of group-oriented cryptographic scheme: Many-to-one encryption and authentication scheme. The many-to-one encryption and authentication scheme is to solve a practical problem, i.e., the scenario that the number of the receivers is very small compared with the number of the senders and a receiver may serve millions of senders. Compared with the traditional methods, the burdens of the receiver and the KGC are reduced greatly. How to revoke a sender from his receiver's legitimate sender group is also proposed and it is efficient compared with some traditional methods. The proposed scheme is proven in the random oracle models. The computational complexity of our scheme is independent of the number of the senders. At the end of the paper, an example is given to show how to use our scheme in online software registration and update.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.4
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• pp.55-65
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• 2020

As corona began to spread around the world, it had such a big impact on many people's lives that the word "Untact Culture" was born. Among them, non-face-to-face meetings naturally became a daily routine as educational institutions and many domestic and foreign companies used video conferencing service platforms. Among many video conferencing service platforms, Zoom, the company with the largest number of downloads, caused many security issues and caused many concerns about Zoom's security. In this paper, Zoom's security problems and vulnerabilities were classified into five categories, and Zoom's latest update to solve those problems and the 90-day security planning project were compared and analyzed. And the problem was solved and classified as unresolved. Three of the five parts have been resolved but are still described as how they should be resolved and improved in the future for the two remaining parts.