• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.161-170
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• 2005

The Certificate Revocation List(CRL) or the Online Certificate Status Protocol(OCSP)has been used to validate certificates. However, the CRL cannot validate certificates in realtime because of the Time-Gap problem and the OCSP server overloads in a large scale secure system. In addition, the client cannot access a wired LAN until the client has been authenticated by the authentication server on the IEEE 802. 1x framework. Therefore, the client cannot validate the authentication server's certificate using a certificate validation server. Thus, the client cannot authenticate the authentication server in realtime. To solve these problems this paper designed a secure system that can protect the content of communications and authenticate users in realtime on a wireless LAN The designed certificate validation protocol was proved that the stability and efficiency of the system was very high, the result of the validation had the presence, the speed of the validation was not affected by the system scale, the number of authorities user must trust was reduced to one, and the overload of the validation server was Protected. And the designed user authentication and key exchange protocols were Proved that the mutual authentication was possible in realtime and the fact of the authentication could be authorized by the CA because of using the authorized certificates.

• Smart Media Journal
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• v.5 no.1
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• pp.114-121
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• 2016

Currently, different medical institutions have been carrying out the e-healthcare system project. The system includes electronic medical record and prescription delivery system, and, the Medical Treatment law permits electronic signature for medical record management, which reduced the relevant costs and enabled sharing medical record. And medical solution using online certificates is expanding its application. In that light, the role of certificates became more important than ever. However, in contrast to active effort made to manage personal certificates, certificates related to medical solutions and other types of work are not being managed properly. Most work-related certificates are saved in office computers, which makes them vulnerable to various security threats. Although certificate servers can be used as a solution to this problem, hospitals must build the server separately and, therefore, small and medium-size hospitals can be reluctant to bear the burden. This study proposed a way to design and implement an effective and secure certificate management system by save the certificate file as a BLOB, using existing resources without needing to build a separate certificate server, at minimized costs.

• 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.

• 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.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.497-502
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• 2004

OCSP has specific characters which can suspend, close, and correct in real time. But, as more clients use the OCSP server verification, more updated information is needed, which can lead to jamming in the OCSP server. To apply this technique of Distributed OCSP server so as to reduce the certificate verification OCSP from jamming. Also, the Distributed OCSP server will solve the problems of the intensive central structure.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.147-154
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• 2006

The certificate status validation mechanism is a critical component of a public key infrastructure based on certificate system. The most generally mechanisms used these days are the use of the certificate revocation list and the real-time certificate status protocol. But the certificate revocation list can not give the real-time certificate status because the certificate is being delivered periodically, and the real-time certificate status protocol method will generate a concentrated load to the server because the protocol in the central server will be accessed whenever a certification is necessary. It will also take a long time to validate the certificate because each trade has to send mass information through the network. This paper will present that real-time validation is guaranteed as the real-time certificate status protocol method and the traffic congestion in the network Is reduced in a way that the certification would be requested using the user information hash value and would be validated using the user information kept in the certification authorities and the service providers. Based on the this study, we suggest a real-time certificate status validation mechanism which can reduce the certificate status validation time using the signed user information hash value. And we confirm speed of certificate status verification faster than existing CRL(Certificate Revocation List) and OCSP(Online Certificate Status Protocol) method by test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9C
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• pp.908-922
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• 2003

The Public Key Infrastructure (PKI) trends to delegate the certificate path processing to the Delegated Path Discovery (DPD) Server and Delegated Path Validation (DPV) server recently. The most critical factor for the selection of the delegated server is to allow the server to be equipped with a high reliability through a low cost, and simple implementation. In this paper, we propose a new certificate path processing scheme employed the trusted CA as the DPD/DPV server by adding the capability of the Validation Authority (VA) to the trusted CA. Since our proposed scheme uses the existing trusted CA as validation server, we can achieve a high trust through a simple implementation for the processing. Besides, we propose an additional scheme for reducing an overhead on the trusted CA. it is obtained by delegating digital signature verification to CAs on the path and by skipping the repeated path processing. As the result, our proposed validation scheme can be performed efficiently with high speed and low computational overhead.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.57-66
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• 2006

In this paper. proposes Multi_Kerberos certification mechanism that improve certification service of based on PKINIT that made public in IETF CAT Working Group. This paper proposed to a certificate other realm because search position of outside realm through DNS and apply X.509 directory certification system, to get public key from DNS server by chain (CertPath) between realms by certification and key exchange way that provide service between realms applying X.509, DS/DNS of based on PKINIT, in order to provide regional services. This paper proposed mechanism that support efficient certification service about cross realm including key management. the path generation and construction of Certificate using Validation Server, and recovery of Session Key. A Design of Multi_Kerberos system that have effects simplify of certification formality that reduce procedures on communication.

• Journal of IKEEE
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• v.19 no.4
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• pp.610-616
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• 2015

In this paper, an electronic ID system satisfying security requirements of authentication certificate was designed using fingerprint recognition. The proposed electronic ID system generates a digital signature with forgery prevention, confidentiality, content integrity, and personal identification (=non-repudiation) using fingerprint information, and also encrypts, sends, and verify it. The proposed electronic ID system exploits fingerprint instead of user password, so it avoids leakage and hijacking. And it provides same legal force as conventional authentication certificate. The proposed electronic ID consists of 4 modules, i.e. HSM device, verification server, CA server, and RA client. Prototypes of all modules are designed and verified to have correct operation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.3
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• pp.97-107
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• 2008

This paper proposes a mutual authentication scheme for mobile router in MANEMO. The NEMO used AAA server in order to authenticate mobile router in nested mobile network. So, this scheme has some problem that increases authentication message overhead and authentication time. The proposed scheme uses temporary certificate that signed by an access router's private key. The temporary certificate authenticates a mobile router when the mobile router entered a MANET domain. The proposed scheme reduces authentication message overhead and authentication time than the scheme to use AAA server when authenticating the mobile router.