• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1107-1110
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• 2004

PKI(Public key Infrastructure)기반에서 CA(Certificate Authority)는 사용자를 인증하기 위해서 인증서를 생성하고, 인증서의 상태를 검증하기위해서 CRL(Certificate Revocation List)를 발행하여 인증서 취소 상태를 확인하도록 한다. CRL을 사용할 경우 사용자의 증가로 인하여 CRL의 크기가 증가 함으로써 많은 부담과 실시간 처리가 어렵다. 이와 같은 단점을 보안하기 위해서 최근에는 실시간 처리가 가능한 OCSP(Online Certificate Status Protocol)방법이 제안되었지만 이 또한 사용자의 급증으로 하나의 OCSP 서버에 집중화 됨으로써 OCSP 서버의 부하가 많이 생긴다. 본 논문에서는 집중 OCSP 서버에서 생기는 부하를 줄이기 위해 여러 개의 OCSP 서버를 두고, 각 OCSP 서버의 응답 처리 시간을 빠르게 하기 위해서 CA가 실시간으로 인증서 취소 정보를 해당 OCSP 서버에게 분배하여 전달하고 Front Server를 둠으로써 각 OCSP의 Load를 모니터링하여 부하가 적게 걸린 OCSP에게 인증서 상태 검증을 함으로써 신뢰성과 각 OCSP 서버의 부하를 줄이는 방안을 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1411-1419
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• 2017

The two factor authentication capability, private key possession and key protection password knowledge, and the strong public key cryptography protocol of PKI authentication have largely contributed to the rapid construction of Internet transaction trusted infrastructure. The reusability of a certificate-based identity for every PKI site was another contribution factor of the spread of PKI authentication. Nevertheless, the PKI authentication has been criticised mainly for the cost of PKI construction, inconvenience of individual certificate management, and difficulties of password management. Recently FIDO authentication has received high attention as an alternative of the PKI authentication. The FIDO authentication is also based on the public key cryptography which provides strong authentication services, but it does not require individual certificate issuance and provides user-friendly and secure authentication services by integrating biometric technologies. The purpose of this paper is to concretely compare the PKI-authentication and FIDO-authentication and, based on the analysis result, to propose their corresponding applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1502-1522
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• 2019

Leakage of secret keys may be the most devastating problem in public key cryptosystems because it means that all security guarantees are missing. The forward security mechanism allows users to update secret keys frequently without updating public keys. Meanwhile, it ensures that an attacker is unable to derive a user's secret keys for any past time, even if it compromises the user's current secret key. Therefore, it offers an effective cryptographic approach to address the private key leakage problem. As an extension of the forward security mechanism in certificate-based public key cryptography, forward-secure certificate-based signature (FS-CBS) has many appealing merits, such as no key escrow, no secure channel and implicit authentication. Until now, there is only one FS-CBS scheme that does not employ the random oracles. Unfortunately, our cryptanalysis indicates that the scheme is subject to the security vulnerability due to the existential forgery attack from the malicious CA. Our attack demonstrates that a CA can destroy its existential unforgeability by implanting trapdoors in system parameters without knowing the target user's secret key. Therefore, it is fair to say that to design a FS-CBS scheme secure against malicious CAs without lying random oracles is still an unsolved issue. To address this problem, we put forward an enhanced FS-CBS scheme without random oracles. Our FS-CBS scheme not only fixes the security weakness in the original scheme, but also significantly optimizes the scheme efficiency. In the standard model, we formally prove its security under the complexity assumption of the square computational Diffie-Hellman problem. In addition, the comparison with the original FS-CBS scheme shows that our scheme offers stronger security guarantee and enjoys better performance.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.11-17
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• 2018

The number of certificates in Korea is about 32,364(2018.09). There are 252 national technical qualifications, 149 national professional qualifications, 99 public private qualifications, and 31,894 private qualifications. The purpose of this study is to examine the process by which KAITS ISE is created. The course was examined and formalized for 10 years from the establishment of KAITS to the first test. As a result of the research, (1) Preparatory considerations (2) Development of qualifications framework (3) Job analysis and drafting (4) Development of problem banks (5) Design of curriculum (6) Development of verification strategy (7) Execution of verification (8) Revenue plan (9) Expansion of qualification demand (10) Opinion formation. After that, the module of the creativity is studied. It is expected that it will be used as a model for certification development in industry security consulting experts.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.277-280
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• 2005

With the proliferation of mobile terminals, use of the Internet in mobile environments is becoming more common. To support mobility in these terminals, Mobile IPv4 is proposed and represents the standard in IPv4 environments. Authentication should be mandatory, because mobile terminals can utilize Internet services in any foreign domain. Mobile IPv4 provides symmetric key based authentication using the default HMAC-MD5. However, symmetric key based authentication creates a key distribution problem. To solve this problem, public key based authentication mechanisms have been proposed. In this paper, the performance of each of these mechanisms is evaluated. The results present that, among these mechanisms, partial certificate based authentication has superior performance, and certificate based authentication has the worst performance. Although current public key based authentication mechanisms have lower performance than symmetric key based authentication, this paper presents the possibility that public key based authentication mechanisms may be used for future mobile terminal authentication.

• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.83-91
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• 2006

In this paper, we improved a cryptography system model based on the secure initial authentication public key with PKINIT of authentication and key recovery protocol. It is applied to all fields of cryptography system using certificate. This study presents two mechanisms to authenticate between member users. The first mechanism is initial authentication and distribution of session key by public key cryptography based on certificate between entity and server, and the second mechanism is a key recovery support protocol considering loss of session key in the secure communication between application servers.

• Convergence Security Journal
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• v.6 no.4
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• pp.11-19
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• 2006

Web service is giving an equal privilege to all user for sharing their resources. Under this situation, a lot of vulnerability against the various attacks through the Internet is possible, more sophisticated security services are necessary. In this paper, we propose an access control scheme using SPKI (Simple Public Infrastructure). The scheme designates an access control by providing the certificate to users who request a connection for resource sharing and limits the resource usage of information provider according to the access right that is given to their own rights.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.90-98
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• 2008

PKI (Public Key Infrastructure) which is used for the security of E-commerce (Electronic-commerce) in wired internet is not suitable for the mobile phone because of the fundamental limitation of performance such as less memory and less powerful CPU. Therefore, we need to develop a wireless PKI (WPKI) that provides the similar security level as the wired PKI supporting mobile phone. In this paper, we propose a lightweight and secure Wireless Certificate Management Protocol (WCMP) that is executable to the mobile phone that has a constrained communication environment and limitation of performance, and show the implementation results of the scheme based on the mobile phone. We minimize data sizes processed in mobile phone, and optimize protocols for the certificate management. This results in the reduced module sizes to be able to install in mobile phone and shows as the same level as the wired CMP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1466-1477
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• 2016

Public key infrastructure(PKI), principle technology of the certificate, is a security technology providing functions such as identification, non-repudiation, and anti-forgery of electronic documents on the Internet. Our government and financial organizations use PKI authentication using ActiveX to prevent security accident on the Internet service. However, like ActiveX, plug-in technology is vulnerable to security and inconvenience since it is only serviceable to certain browser. Therefore, the research on HTML5 authentication system has been conducted actively. Recently, domestic bank introduced PKI authentication complying with web standard for the first time. However, it still has inconvenience to register a certification on each website because of same origin policy of web storage. This paper proposes the certificate based SSO protocol that complying with web standard to provide user authentication using certificate on several sites by going around same origin policy and its security proof.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.59-66
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• 2006

A Certification Authority issues X.509 public key certificates to bind a public key to a subject. The subject is specified through one or more subject names in the 'subject' or 'subjectAltName' fields of a certificate. In reality, however, there are individuals that have the same or similar names. This ambiguity can be resolved by including a 'permanent identifier' in all certificates issued to the same subject, which is unique across multiple CAs. But, a person's unique identifier is regarded as a sensitive personal data. Such an identifier cannot simply be included as part of the subject field, since its disclosure may lead to misuse. We present a new method for secure and accurate user authentication through the PEPSI included in the standard certificate extension of a X.509 certificate. The PEPSI can be served not only for user authentication but also for the user anonymity without divulging personal information.