• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.29-46
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• 2002

We generally use SSL/TLS protocol utilizing X.509 v3 certificates so as to provide a secure means in establishment an confidential communication and the support of the authentication service. SPKI/SDSI was motivated by the perception that X.509 is too complex and incomplete. This thesis focuses on designing a secure server and an implementation of the prototype which has two main modules, one is to support secure communication and RBAC, not being remained in the SPKI/SDSI server which was developed by the existing Geronimo project and the other is to wholly issue name-certificate and authorization-cerificate. And the demonstration embodied for our sewer is outlined hereafter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.10
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• pp.2862-2882
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• 2023

With the development of networking technology, it has become common to use various types of network services to replace physical ones. Among all such services, electronic voting is one example that tends to be popularized in many countries. However, due to certain concerns regarding information security, traditional paper voting mechanisms are still widely adopted in large-scale elections. This study utilizes blockchain technology to design a novel electronic voting mechanism. Relying on the transparency, decentralization, and verifiability of the blockchain, it becomes possible to remove the reliance on trusted third parties and also to enhance the level of trust of voters in the mechanism. Besides, the mechanism of blind signature with its complexity as difficult as solving an elliptic curve discrete logarithmic problem is adopted to strengthen the features related to the security of electronic voting. Last but not least, the mechanism of self-certification is incorporated to substitute the centralized certificate authority. Therefore, the voters can generate the public/private keys by themselves to mitigate the possible risks of impersonation by the certificate authority (i.e., a trusted third party). The BAN logic analysis and the investigation for several key security features are conducted to verify that such a design is sufficiently secure. Since it is expected to raise the level of trust of voters in electronic voting, extra costs for re-verifying the results due to distrust will therefore be reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.370-378
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• 2008

The CEDA(Certified E-Document Authority) is a reliable third party that deposit electronic document having legal effects securely, and verify contents of document or transmission. This paper focuses on a function of secure transmission among several important functions, and implements public key encryption system for secure transmission when server and user communicate for image transmission. This paper follows a standard fundamental rule of X.509 in ITU-T, and it uses symmetric encryption algorithm to raise speed of a large data operation. A key of symmetric encryption algorithm is encrypted by private key in public key system, it protects to be modified using digital signature for data integrity. Also it uses certificates for mutual authentication.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.1
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• pp.13-31
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• 2023

Korean Government-PKI (GPKI) is a public-key infrastructure which provides authentication and security functions for information system used by central government, local governments, and public institutions of the Republic of Korea to provide their own administrative and public services. The current cryptosystem of GPKI was established in the early 2000s, and more than ten years have passed since the last improvement in 2010. Over the past decade or so, the information security, including cryptography, has undergone many changes and will continue to face many changes. Therefore, for the sustainable security of GPKI, it is necessary to review the security of the cryptosystem at this point. In this paper, we analyze the current status and the security of technologies and standards used in the system. We identify cryptographic algorithms with degraded security, international standards which are obsoleted or updated, and cryptographic parameters that should be revised for the high security level. And based on this, we make several suggestions on the reorganization of cryptographic algorithms and related technologies for the security enhancement of GPKI.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.281-286
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• 2003

Nowadays, a patient's private medical data which is exposed to the outside world has a severe effect on not only the patient's private life but also his/her social activities and environment. So, it is important to securely protect the patient's private medical data from the illegal manipulation. This paper studies the method to store the electronic prescription information in an IC card. For that, an access control for users, such as a doctor, a nurse, a medical institute member, a pharmacy, a pharmacist, or a patient, is proposed to access the data stored in an IC card. The certificate is issued using the Crypto API of a certificate management model supported by Windows 2000. The public/private key is created by the Cryptographic Service Provider program, and the electronic prescription is signed using the digital signature. The proposed system, therefore, can improve the quality of medical services by securing the safety and integrity of the electronic prescription, stored in an IC card.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.199-206
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• 2003

one of the representative micropayment protocols. The original PayWord system is designed for a user who generates paywords by performing hash chain operation for payment to an only designated vendor. In other words, a user has to create new hash chain values in order to establish commercial transactions with different vendors on the Internet. Therefore, we suggest an efficient scheme that is able to deal with business to different vendors by using only one hash chain operation to supplement this drawback. In this proposed system, a broker creates a new series of hash chain values along with a certificate for the user's certificate request. This certificate is signed by a broker to give authority enabling a user to generate hash chain values. hew hash chain values generated by a broker provide means to a user to do business with multiple vendors.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.641-652
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• 2002

In this paper, proposes Kerberos certification mechanism that improve certification service of PKINIT base that announce in IETF CAT Working Group. Bid to certificate other realm because search position of outside realm through DNS and apply X.509 directory certification system, acquire 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 PKINIT base. In order to provide regional services, Certification and key exchange between realms use Kerberos symmetric method and Session connection used Directory service to connection X.509 is designed using an asymmetric method. By efficient TGT (Ticket Granting Ticket) exchange and reusability of ticket, A Design of Kerberos system that have effect and simplification of certification formality that reduce overload on communication.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.499-506
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• 2005

A hash chain is a structure organized by hash function with high speed in computation. Systems using the hash chain are using extensively in various cryptography applications such as one-time passwords, server-supported signatures and micropayments. However, the most hash chain based on the system using pre-paid method provides anonymity but has the problem to increase payment cost. In this paper, we propose a new hash chain based on the micropayment system to keep user anonymity safe through blind signature in the withdrawal process of the root value without disclosing privacy information, and to improve efficiency by using secret key instead of public key in the system without the role of certificate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.419-427
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• 2009

This paper propose DA-UDC(Double Authentication User, Device, Cross) Module which solves the cost problem and the appropriation of Certificate using User Authentication, Device Authentication and Cross Authentication with OTA(One Time Authentication) Key, and which is designed not to subscribe to the service of Home network business. Home Server transmits its public key which is needed to create OTA to the user which passed the first step of authentication which verifies User ID, Device ID and Session Key. And it performs the second step of authentication process which verifies the OTA key created by a user. Whenever the OTA key of DA-UDC module is generated, the key is designed to be changed. Therefore, DA-UDC Module prevents the exposure of User and Device ID by performing the two steps of authentication and enhances the authentication security of Home Network from malicious user with OTA key. Also, DA-UDC Module is faster than the existing authentication system in processing speed because it performs authentication calculation only once. Though DA-UDC Module increases data traffic slightly because of the extra authentication key, it enhances the security more than the existing technique.

• 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.