• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.309-315
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• 2007

It is X.509 certificate that use to offer authentication and delegation service in grid. Authentication service offers by X.509 user certificate, and delegation service offers by X.509 proxy certificate. However, in case of provide delegation service using X.509 poxy certificate, can not fulfill complicated delegation requirement of grid. In this paper, proposed delegation mechanism that is done restricted delegation, multiple delegation and light weight that delegation service that use existent X.509 proxy certificate does not have. In this paper, delegation service that proposed used SPKI certificate.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.693-697
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• 2010

In current e-commerce system, it happens that client's confidential information such as credit card numbers, pin numbers, or digital certificate may pass through a web proxy server or an altered proxy server without client's awareness. Even though the confidential information is encrypted and sent through SSL(Secure Sockets Layer) or TLS(Transport Layer Security) protocol, it can be exposed to the risk of sniffing by the digital certificate forgery at the proxy server, which is called the SSL MITM(Man-In-The-Middle) Proxy attack. In this paper, current credit card web-payment systems, which is weak at proxy information alternation attack, are analyzed. A resolution with certificate proxy server is also proposed to prevent the MITM attack.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.287-294
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• 2003

Authentication and authorization are essential functions for the security of distributed network environment. Authorization is determining and to decide whether a user or process is permitted to perform a particular operation. In this paper, we design an authorization mechanism to make a system more effective with Kerberos for authentication mechanism. In the authorization mechanism, Kerberos server operates proxy privilege server. Proxy privilege server manages and permits right of users, servers and services with using proposed algorithm. Also, privilege attribute certificate issued by proxy privilege server is used in delegation. We designed secure kerberos with proposed functions for effective authorization at the same time authentication of Kerberos mechanism.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.273-280
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• 2003

When an existing user authorization systems in Grid access many user to local system and subject DN (Distinguished Name) in a user-proxy authenticate and ID in local system is one-to-one mapping, they have difficulties in ID management, memory resource management and resource management. At this, a variety of subject DN is shared of one local ID in an existing Grid. But this faces many difficulties in applying all requirements for many Grid users. Thus, we suppose user authorization system based on a certificate not them based on ID in this paper. That is, we add user's access level to extension field in a certificate, and make a supposed authorization system decide access limitation level on resources instead of an existing ID mapping methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5C
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• pp.737-749
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• 2004

Kerberos authenticates clients using symmetric-key cryptography, and supposed to Oust other systems of the realm in distributed network environment. But, authentication and authorization are essential elements for the security. In this paper, we design an efficient and secure authentication/authorization mechanism by introducing the public/private-key and installing the proxy privilege server to Kerberos. In the proposed mechanism, to make a system more secure, the value of the session key is changed everytime using MAC(message authentication code) algorithm with the long-term key for user-authentication and a random number exchanged through the public key. Also, we reduce the number of keys by simplifying authentication steps. Proxy privilege server certifies privilege request of client and issues a privilege attribute certificate. Application server executes privilege request of client which is included a privilege attribute certificate. Also, a privilege attribute certificate is used in delegation. We design an efficient and secure authentication/authorization algorithm with Kerberos.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.890-891
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• 2013

인터넷이 발달함에 따라 사용자들은 웹에서 여러 가지 일의 처리가 가능하게 되었다. 최근에는 휴대폰의 성능과 기능이 발달하고 스마트폰의 보급이 급속히 확산되면서 스마트폰을 사용하여 많은 양의 데이터들의 전달이 이루어지고 있다. 이러한 처리 과정에서 개인 및 기업정보들이 유출될 수 있는 위험이 증가하고, 스마트폰과 클라이언트 사이에서의 개인, 기밀 정보가 SSL (Secure Sockets Layer) 또는 TLS (Transport Layer Security)프로토콜을 통해 암호화 되어 전송 되어도 프록시 서버에서 인증서 변조를 통하여 유출될 가능성이 점점 높아지고 있다. 본 논문에서는 스마트폰 상의 안전한 통신을 위해 많이 이용되는 SSL/TLS의 전송구간에 대한 취약점 분석 등 보안 이슈와 연구 방향에 대해 논의한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8B
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• pp.730-737
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• 2003

In this paper, we present an efficient authentication proxy for IEEE 802.1x systems based on the port-based access control mechanism. An IEEE 802.1x system consists of PC supplicants, a bridge with authentication client functions, and an authentication server. For the network security and user authentication purposes, a supplicant who wants to access Internet should be authorized to access the bridge port using the Extended Authentication Protocol (EAP) over LAN. The frame of EAP over LAN is then relayed to the authentication server by the bridge. After several transactions between the supplicant and the server via the bridge, the supplicant may be either authorized or not. Noting that the transactions between the relaying bridge and the server will be increased as the number of supplicants grows in public networks, we propose a scheme for reducing the transactions by employing an authentication proxy function at the bridge. The proxy is allowed to cache the supplicant's user ID and password during his first transaction with the server. For the next authentication procedure of the same supplicant, the proxy function of the bridge handles the authentication transactions using its cache on behalf of the authentication server. Since the main authentication server handles only the first authentication transaction of each supplicant, the processing load of the server can be reduced. Also, the authentication transaction delay experienced by a supplicant can be decreased compared with the conventional 802.1x system.

• 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.