• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.253-256
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• 2002

법인에서 권한의 위임을 통한 대리 서명은 이미 오프라인에서 널리 사용되고 있다. 이러한 대리 서명을 온라인 상에서 사용하기 위해서는 법인은 위임자에게 위임 인증서를 발급하고 위임자는 그 인증서로 대리서명을 하여 온라인 상에서 업무를 수행할 수 있다. 그러나 이러한 기술을 사용하기 위해서는 위임자의 권한 위임장이 위 변조와 오남용의 위험으로부터 안전하게 보호되어야 한다는 요구 사항이 먼지 만족 되야 하는 필요성이 있다. 위임 인증서는 안전한 대리 서명을 효과적으로 달성하기 위해 등장하였으며 현재 여러 가지 응용 서비스가 제안되고 있다. 본 논문에서는 법인이라는 특수한 환경에서 위임 인증서를 이용하여 안전한 대리서명을 사용할 수 있는 기술과 방법을 제안한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.153-156
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• 2002

실생활에서 권한의 위임을 통한 대리서명은 일상적으로 널리 사용되고 있다. 이러한 대리서명을 온라인상에서 사용하기 위해서는 위임자의 권한위임장이 안전하게 유통되어야 하고 대리자의 권한 오남용을 막아야 한다. 이에 따라 IETF의 PKIX 워킹그룹에서는 위임인증서(proxy certificate)를 제안하였다. 본 논문에서는 대리자의 권한의 오남용을 막기위해 위임제한 필드를 제안하였고, 위임 인증서의 서비스 가능성을 보이기 위한 프로토타입을 설계하고 구현하였다.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.33-39
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• 2009

The need for end-to-end security has been increased with the widespread use of mobile devices in wireless internet access applications such as mobile commerce. The WAP1.x has an end-to-end security problem that the message transmitted between the mobile device and the Web server is decrypted inside the gateway within a short time. To overcome this problem, several protocols including WAP2.0 has been proposed. These protocols require that the heavy modules such as TLS or data compression modules should be installed on the mobile device with limited resources. This paper proposes a new WTLSW(WTLS-TLS at Web server) protocol and a new WAP2.0 proxy model in order to ensure end-to-end security between the mobile device and the Web server and to be appropriate for mobile devices with limited resources.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.147-155
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• 2013

Proxy re-encryption scheme has advantage where plaintext does not get exposed during re-encryption process. This scheme is popular for sharing server-saved data in case of cloud computing or mobile office that uses server to save data. Since previous proxy re-encryption schemes can use re-encryption key over and over again, it may abuse re-encryption. To solve this problem, conditional proxy re-encryption scheme was proposed. But, it is computationally expensive generate the same number of re-encryption key with the number of condition values. In this paper, we propose an efficient conditional proxy re-encryption scheme in terms of re-encryption key generation. The proposed scheme uses only encryption and decryption process. Therefore it has advantage to generate one re-encryption key for one person. The proposed scheme is secure against chosen-ciphertext attack.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.9_10
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• pp.441-451
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• 2008

Currently, the X.509 proxy certificate is widely used to delegate an entity's right to another entity in the computational grid environment. However it has two drawbacks: the potential security threat caused by intraceability of a delegation chain and the inefficiency caused by an interactive communication between the right grantor and the right grantee on the delegation protocol. To address these problems for computational grids, we propose a new delegation protocol without additional cost. We use an ID-based key generation technique to generate a proxy private key which is a means to exercise the delegated signing right. By applying the ID-based key generation technique, the proposed protocol has the delegation traceability and the non-interactive delegation property. Since the right delegation occurs massively in the computational grid environment, our protocol can contribute the security enhancement by providing the delegation traceability and the efficiency enhancement by reducing the inter-domain communication cost.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1996.11a
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• pp.185-189
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• 1996

외부의 불법 침입자로부터 내부 네트웍 보안을 위한 하나의 솔루션으로 방화벽이 제공되고 있다. 방화벽은 크게 패킷필터링 방식과 어플리케이션 방식의 방화벽으로 나누어지는데 어플리케이션방식은 프락시 기능을 이용한다. 본 논문에서는 어플리케이션 방식의 방화벽에서 FTP Proxy, SMTP Proxy를 통한 파일전송시 바이러스 차단 및 HTTP Proxy를 통한 음란, 폭력물과 같은 불건전정보를 차단하는 방법을 제시하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.885-888
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• 2009

Radio Frequency IDentification (RFID) is a method of remotely storing and retrieving data using small and inexpensive devices called RFID tags. In this paper we propose a proxy agent framework that uses a personal device for privacy enforcement and increased protection against eavesdropping, impersonation and cloning attacks. Using the proxy model a user decides when and where information carried in a tag will be released. In particular, the user can put tags under her/his control, authenticated requests, release tags, transfer them to new owners, and so on. In this paper, we analyses a new type of simple a framework for enhancing RFID security by means of a proxy, a personal device that assumes control of a user's tags.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.5039-5061
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• 2017

Cloud storage becomes a new trend that more and more users move their data to cloud storage servers (CSSs). To ensure the security of cloud storage, many cloud auditing schemes are proposed to check the integrity of users' cloud data. However, most of them are based on public key infrastructure, which leads to complex certificates management and verification. Besides, most existing auditing schemes are inefficient when user uploads a large amount of data or a third party auditor (TPA) performs auditing for multiple users' data on different CSSs. To overcome these problems, in this paper, we propose an efficient and secure auditing scheme based on identity-based cryptography. To relieve user's computation burden, we introduce a proxy, which is delegated to generate and upload homomorphic verifiable tags for user. We extend our auditing scheme to support auditing for dynamic data operations. We further extend it to support batch auditing in multiple users and multiple CSSs setting, which is practical and efficient in large scale cloud storage system. Extensive security analysis shows that our scheme is provably secure in random oracle model. Performance analysis demonstrates that our scheme is highly efficient, especially reducing the computation cost of proxy and TPA.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.353-360
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• 2017

The Internet of Things(IoT) security has more need than a technical problem as it needs series of regulations and faultless security system for common purposes. So, this study proposes an efficient key management in order that can be trusted IoT data in cloud computing. In contrast with a key distribution center of existing sensor networks, the proposed a federation key management of cloud proxy key server is not central point of administration and enables an active key recovery and update. The proposed key management is not a method of predetermined secret keys but sharing key information of a cloud proxy key server in autonomous cloud, which can reduce key generation and space complexity. In addition, In contrast with previous IoT key researches, a federation key of cloud proxy key server provides an extraction ability from meaningful information while moving data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.15-22
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• 2002

Java applet, executed in user's web browsers which is via proxy server on web sever, can approach client files or resources, so it is necessary to secure against malicious java applet. Currently, the previous security countermeasures against malicious java applet use two ways: one is making a filter system to detect malicious java applet hewn in proxy, the other is that establishes another security java virtual machine. However, the first one can not detect unknown malicious java applet, and the other one nay increase loads, because it decides whether there is malicious or not after implementing java applet on proxy server. In this paper, after inserting monitoring function to java applet on proxy server using java-methods substitution and transfer it to user to detect malicious java applet, we propose a technique for detecting malicious java applet that can detect the unknown malicious java applet with reducing loads