• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.359-362
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• 2014

With recent growing of application service, servers are required to sustain great amount of data and to handle them quickly: besides, data must be processed securely. The main security algorithm used in security services of server is AES(Advanced Encryption Standard - 2001 published by NIST), which is widely accepted in the world market for superiority of performance. In Korea, NSRI(National Security Research Institute) has developed ARIA(Academy, Research Institute, Agency) algorithm in 2004 and LEA(Lightweight Encryption Algorithm) algorithm in 2012. In this paper, we show advantage of LEA by comparing performance with AES and ARIA in various servers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2167-2176
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• 2016

In the multi-server environment, remote user authentication has a very critical issue because it provides the authorization that enables users to access their resource or services. For this reason, numerous remote user authentication schemes have been proposed over recent years. Recently, Lin et al. have shown that the weaknesses of Baruah et al.'s three factors user authentication scheme for multi-server environment, and proposed an enhanced biometric-based remote user authentication scheme. They claimed that their scheme has many security features and can resist various well-known attacks; however, we found that Lin et al.'s scheme is still insecure. In this paper, we demonstrate that Lin et al.'s scheme is vulnerable against the outsider attack and user impersonation attack, and propose a new biometric-based scheme for authentication and key agreement that can be used in the multi-server environment. Lastly, we show that the proposed scheme is more secure and can support the security properties.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.585-596
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• 2001

In this paper, a new stream cipher algorithm based on the chaos theory is proposed and is applied to a Web security system. The Web security system is composed of three parts： certificate authority (CA), Web client, and Web server. The Web client and server system include a secure proxy client (SPC) and a secure management server (SMS), respectively, for data encryption and decryption between them. The certificate is implemented based on X.509 and the RSA public key algorithm is utilized for key creation and distribution to certify both the client and server. Once a connection is established between the client and server, outgoing and incoming data are encrypted and decrypted, respectively, using one of the three cipher algorithms： chaos, SEED, and DES. The proposed chaos algorithm outperforms the other two conventional algorithms in processing time and complexity. Thus, the developed Web security system can be widely used in electronic commerce (EC) and Internet banking.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.3
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• pp.541-548
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• 2017

The smartphone operates the media server daemon to handle audio service requests. Media server daemons, running with a high privilege in the background, caused many vulnerabilities to applications most frequently used in smart devices including smartphones. Fuzzing is a popularly used methodology to find software vulnerabilities. Unfortunately, fuzzing itself is not much effective in such format-strict environments as media services. In this paper, we propose a file format-aware fuzzing in order to efficiently detect vulnerabilities of media server daemon. We acquired a remote arbitrary code execution vulnerability on iOS/tvOS/MacOS/watchOS, and we verified the effectiveness by comparing our methodology with the fuzzers FileFuzz and ZZUF.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.139-147
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• 2010

A remote user authentication scheme is a two-party protocol whereby an authentication server in a distributed system confirms the identity of a remote individual logging on to the server over an untrusted, open network. In 2005, Liao et al. proposed a remote user authentication scheme using a smart card, in which users can be authenticated anonymously. Recently, Yoon et al. have discovered some security flaws in Liao et al.'s authentication scheme and proposed an improved version of this scheme to fix the security flaws. In this article, we review the improved authentication scheme by Yoon et al. and provide a security analysis on the scheme. Our analysis shows that Yoon et al.'s scheme does not guarantee not only any kind of authentication, either server-to-user authentication or user-to-server authentication but also password security. The contribution of the current work is to demonstrate these by mounting two attacks, a server impersonation attack and a user impersonation attack, and an off-line dictionary attack on Yoon et al.'s scheme. In addition, we propose the enhanced authentication scheme that eliminates the security vulnerabilities of Yoon et al.'s scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.163-177
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• 2008

As many companies are considering to use server virtualization technology to reduce cost, the crime rates in virtual server environment are expected to be increasing rapidly. The server virtualization solution has a basic function to produce virtual machine images without using any other disk imaging tools, so that investigating virtual servers are more efficient because the investigator only has to collect the virtual machine image and submit it to the court. However, the virtual machine image has no admissibility to be the legal evidence because of security, authenticity, procedural problems in collecting virtual machine images on virtual servers. In this research, we are going to provide requirements to satisfy security, authenticity and chain of custody conditions for the admissibility of the virtual machine image in server virtualization environment. Additionally, we suggest definite roles and driving plans for related organizations to produce virtual machine image as a admissible evidence.

• The Transactions of the Korea Information Processing Society
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• v.6 no.3
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• pp.641-653
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• 1999

The paper is design and implementation of the system to support security communication between a Web Browser and a CGI program by a Web Server using PKI(Public Key Infrastructure. This system uses GSS(Generic Security Service)-API to communicate with PKI, offers a Web user a Client Proxy, and offers a CGI developer there library functions related with security. TLS(Transport Layer Security) supports security communication between a Web Browser and a Web Server, but the system supports security communication between a Web Browser and a CGI program as the protected data received from a Client Proxy are sent to a CGI program, and the CGI program decrypts the data using the library functions supported by this system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.2
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• pp.289-299
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• 2024

Blockchains are not efficient for real-time processing because the growing number of transactions and users delays many computations and network communications. This study proposes a cloud proxy server, so that legitimate users can use blockchain as well as reduce network latency. To proceed with a blockchain transaction, the blockchain copy server verifies all transaction-related data, but the cloud proxy server verifies legitimate users with a simple zero-knowledge proof algorithm, enabling efficient blockchain real-time processing. The cloud proxy server can support blockchain anonymity, security, and scalability that can verify legitimate users with the proposed zero-knowledge proof by receiving the registered key pair of the blockchain user. In the proposed research analysis, blockchain-based cloud proxy server reduces network latency compared to previous studies and key processing on cloud proxy servers reduces the cost of key computation compared to previous studies.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.281-284
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• 2005

Kerberos is system that offer authorization in internet and authentication service. Can speak that put each server between client and user in distributed environment and is security system of symmetry height encryption base that offer authentication base mutually. Kerberos authentication is based entirely on the knowledge of passwords that are stored on the Kerberos Server. A user proves her identity to the Kerberos Server by demonstrating Knowledge of the key. The fact that the Kerberos Server has access to the user's decrypted password is a rwsult of the fact that Kerberos does not use public key cryptogrphy. It is a serious disadvantage of the Kerbercs System. The Server must be physically secure to prevent an attacker from stealing the Kerberos Server and learning all of the user passwords. Kerberos was designend so that the server can be stateless. The Kerberos Server simply answers requests from users and issues tickets. This study focused on designing a SIP procy for interworking with AAA server with respect to user authentication and Kerberos System. Kerberos is security system of encryption base that offer certification function mutually between client application element and server application element in distributed network environment. Kerberos provides service necessary to control whether is going to approve also so that certain client may access to certain server. This paper does Credit-Control Server's function in AAA system of Diameter base so that can include Accounting information that is connected to Rating inside certification information message in Rating process with Kerberos system.

• Convergence Security Journal
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• v.8 no.4
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• pp.199-207
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• 2008

Web service has many security weekness because it is exposure to outside and connected with various application. Especially, as new technology developed new type of security weakness has occured consistently. In this paper, we construct webserver and honeyweb by using virtual reality on a basis these weakness. So it cannot be influenced by any attack to the hardware of the system. By using honey web, it disigned and embodied web server secutiry system to collect the data about new attack. Through this, it can provide proper secutiry in a web environment of mutual communication.