• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.227-230
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• 2013

Financial transactions using a mobile terminal and the Internet is activated, it is a stock exchange enabled using mobile devices and the Internet. Koscom in charge of IT operations of securities transaction-related in (securities ISAC), to analyze the vulnerability of information security related to securities transactions, which corresponds to running the integrated security control system. Online stock trading is a subject to the Personal Information Protection Act, electronic systems of related, has been designated as the main information and communication infrastructure to, damage financial carelessness of the user, such as by hacking is expected to are. As a result, research on the key vulnerabilities of information security fields related to securities business cancer decoding of the Securities and Exchange packet, through the analysis of security events and integrated security control is needed.

• Journal of KIISE:Software and Applications
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• v.28 no.11
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• pp.864-873
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• 2001

In this paper, a new approach to building a registration authority for issuing PKI-based certificates is presented to make the process of identifying an individual more secure and reliable by utilizing human iris recognition technology. The tasks of the proposed system associated with the manipulation of irises except for the general functions of registration authorities can be categorized into three modules, the acquisition of iris images, the registration of iris information, and the verification of users by means of iris patterns. The information among the three modules is safely exchanged through encryption and decryption with a symmetric cryptographic method. As a feature extraction method for a given iris image, a wavelet transform is applied to represent a feature vector with a small dimension of information obtained by subsampling an image corresponding to lower frequency bands successively without loss of information. Through the experiments on human iris recognition technology we proposed and applied to the registration authority, the potential of biometric technology in various applications is confirmed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.5
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• pp.451-457
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• 2016

To improve security in the data communication field, many studies on the application of chaotic signals to encryption have been conducted in recent years. In this study, a new security protocol where the initial value sensitivity and noise similarity of chaotic signals have been applied to an RFID communication channel was designed. In the case of chaotic systems, if the initial values become identical, the same signals are generated at the same time after that point even though the two systems have been calculated independently. Therefore, an unpredictable security channel can be produced based on such characteristics. However, a security channel can be produced only when an initial value is shared in advance, and thus there is a potential problem of infringement during the transmission of the initial value. To resolve this problem, a method in which a certain proportion of new chaotic signals are applied to two chaotic systems for communication and are then synchronized after some time was proposed. This new method can conceal the initial value, and thus can resolve the problem of the existing communication method using chaotic signals. The designed method was verified with the encryption and decryption of images. It is expected that a more secure RFID system could be established by applying the communication protocol proposed in this study to insecure RFID communication channels.

• 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.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.55-66
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• 2004

Recently, as the personal computers are supplied rapidly, they formed the nucleus of the computer system. But, because of the easiness that anyone uses them to go near easily, it is the fact that the security of personal computer is weakness. So, in the paper, 1 propose the technical method that minimizes the loss and leakage of important data. This paper implemented a crypto system for security of data file on personal computer and assistance storage medium. The way of encryption/decryption is applied by complexity method which mixed Diffie-Hellman key exchange protocol, a typical RC4(Rivest Cipher version 4) algorithm of stream cipher and a typical MD5(Message Digest version 5) of Hash Function. For valuation implemented crypto system, three criteria is presented, which are crypto complexity, processing time and pattern matching. And according to analysis the three criteria the crypto system is verified the security, efficiency and usefulness. The crypto system is programmed with Visual C++ language of Microsoft. And so, as this is software system, we shall have a technical security system at a minimum cost for all personal computer.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.8
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• pp.918-929
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• 1999

동기식 스트림 암호통신 방식을 사용하는 암호통신에서는 암/복호화 과정 수행시 암호통신 과정에서 발생하는 사이클슬립으로 인해 키수열의 동기이탈 현상이 발생되고 이로 인해 오복호된 데이타를 얻게된다. 이러한 위험성을 감소하기 위한 방안으로 현재까지 암호문에 동기신호와 세션키를 주기적으로 삽입하여 동기를 이루는 주기적인 동기암호 통신방식을 사용하여 왔다. 본 논문에서는 CDMA(Cellular Division Multiple Access) 이동망에서 데이타서비스를 제공할 때 사용되는 점대점 프로토콜의 주소영역의 특성을 이용하여 단위 측정시간 동안 측정된 주소비트 정보와 플래그 패턴의 수신률을 이용하여 문턱 값보다 작은경우 동기신호와 세션키를 전송하는 비주기적인 동기방식을 사용하므로써 종래의 주기적인 동기방식으로 인한 전송효율성 저하와 주기적인 상이한 세션키 발생 및 다음 주기까지의 동기이탈 상태의 지속으로 인한 오류확산 등의 단점을 해결하였다. 제안된 알고리즘을 링크계층의 점대점 프로토콜(Point to Point Protocol)을 사용하는 CDMA 이동망에서 동기식 스트림 암호 통신방식에 적용시 동기이탈율 10-7의 환경에서 주기가 1sec인 주기적인 동기방식에서 요구되는 6.45x107비트에 비해 3.84x105비트가 소요됨으로써 전송율측면에서의 성능향상과 오복호율과 오복호 데이타 비트측면에서 성능향상을 얻었다. Abstract In the cipher system using the synchronous stream cipher system, encryption / decryption cause the synchronization loss (of key arrangement) by cycle slip, then it makes incorrect decrypted data. To lessen the risk, we have used a periodic synchronous cipher system which achieve synchronization at fixed timesteps by inserting synchronization signal and session key. In this paper, we solved the problem(fault) like the transfer efficiency drops by a periodic synchronous method, the periodic generations of different session key, and the incorrectness increases by continuing synchronization loss in next time step. They are achieved by the transfer of a non-periodic synchronous signal which carries synchronous signal and session key when it is less than the threshold value, analyzing the address field of point-to-point protocol, using the receiving rate of address bits information and flag patterns in the decision duration, in providing data services by CDMA mobile network. When the proposed algorithm is applied to the synchronous stream cipher system using point-to-point protocol, which is used data link level in CDMA mobile network, it has advanced the result in Rerror and Derror and in transmission rate, by the use of 3.84$\times$105bits, not 6.45$\times$107bits required in periodic synchronous method, having lsec time step, in slip rate 10-7.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.7
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• pp.402-413
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• 2004

This paper presents an Implementation of Korean standard 128-bit block cipher SEED for the small (8 or 16-bits) embedded system using a low-cost FPGA(Field Programmable Gate Array) chip. Due to their limited computing and storage capacities most of the 8-bits/16-bits small embedded systems require a separate and dedicated cryptography processor for data encryption and decryption process which require relatively heavy computation job. So, in order to integrate the SEED with other logic circuit block in a single chip we need to invent a design which minimizes the area demand while maintaining the proper performance. But, the straight-forward mapping of the SEED specification into hardware design results in exceedingly large circuit area for a low-cost FPGA capacity. Therefore, in this paper we present a design which maximize the resource sharing and utilizing the modern FPGA features to reduce the area demand resulting in the successful implementation of the SEED plus interface logic with single low-cost FPGA. We achieved 66% area accupation by our SEED design for the XC2S100 (a Spartan-II series FPGA from Xilinx) and data throughput more than 66Mbps. This Performance is sufficient for the small scale embedded system while achieving tight area requirement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2197-2204
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• 2015

In recent times, the high-tech society has become the most important issue by IT technology and publication network. Today such flows have also been the case in the e-book field. Today's electronic publication is changing day by day. But there are some problems according to the prevalence of e-book. E-book is similar to p-book(paper-book). There is a limit to have perfect feeling of a texture of p-book. In order to purchase an e-book, people use online. People having malicious intent could copy and distribute it illegally. It leads to cyber abuses. This paper aims at the copyright protection of e-book ePub writers. The proposed e-book copyright protection system is designed using e-book production Sigil environment and C program environment. This system uses client-server communication through e-book ePub as authentication information. It discerns whether to permit or not for a client to read the e-book using authentication information. Authentication information includes ID, password, IP address, limited time of authentication information, GUID(Globally Unique Identifier). If authentication information about e-book meets requirements, people can use it. But if not, it blocks people's approach by quitting program.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1000-1008
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• 2009

It also increases the competitive power of the nation. With all these merits of electronic documents, there exist threats to the security such as illegal outflow, destroying, loss, distortion, etc. Currently, the techniques to protect the electronic documents against illegal forgery, alteration or removal are not enough. Until now, various security technologies have been developed for electronic documents. However, most of them are limited to prevention of forgery or repudiation. Cryptography for electronic documents is quite heavy that direct cryptography is not in progress. Additionally, key management for encryption/decryption has many difficulties that security has many weak points. Security has inversely proportional to efficiency. It is strongly requested to adopt various cryptography technologies into the electronic document system to offer more efficient and safer services. Therefore, this paper presents some problems in cryptography technologies currently used in the existing electronic document systems, and offer efficient methods to adopt cryptography algorithms to improve and secure the electronic document systems. To validate performance of proposed method compare with the existing cryptographies, critical elements have been compared, and it has been proved that the proposed method gives better results both in security and efficiency.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.4
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• pp.226-238
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• 2010

OpenSSL is an open-source library implementing SSL that is a secure communication protocol. However, the library has a severe vulnerability that its security information can be easily exposed to malicious software when the library is used in a form of shared library on Linux and UNIX operating systems. We propose a scheme to attack the vulnerability of the OpenSSL library. The scheme injects codes into a running client program to execute the following attacks on the vulnerability in a SSL handshake. First, when a client sends a server a list of cryptographic algorithms that the client is willing to support, our scheme replaces all algorithms in the list with a specific algorithm. Such a replacement causes the server to select the specific algorithm. Second, the scheme steals a key for data encryption and decryption when the key is generated. Then the key is sent to an outside attacker. After that, the outside attacker decrypts encrypted data that has been transmitted between the client and the server, using the specified algorithm and the key. To show that our scheme is realizable, we perform an experiment of collecting encrypted login data that an ftp client using the OpenSSL shared library sends its server and then decrypting the login data.