• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.525-535
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• 2005

A password-based authenticated tripartite key exchange protocol based on A. Joux's protocol was proposed. By using encryption scheme with shared password, we can resolve man-in-the-middle attack and lack of authentication problems. We also suggested a scheme to avoid the offline dictionary attack to which symmetric encryption schemes are vulnerable. The proposed protocol does not require a trusted party which is required in certificate or identity based authentication schemes. Therefore in a ad hoc network which is difficult to install network infrastructure, the proposed protocol would be very useful. The proposed protocol is more efficient in computation aspect than any existing password-based authenticated tripartite key exchange protocols. When it is used as a base line protocol of tree based group key exchange protocol, the computational weak points of the proposed protocol are compensated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.81-86
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• 2009

Almost all network systems provide an authentication mechanism based on user ID and password. In such system, it is easy to obtain the user password using a sniffer program with illegal eavesdropping. The one-time password and challenge-response method are useful authentication schemes that protect the user passwords against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. In this paper, we propose a new identification scheme One Pass Identification. The security of Password base System is based on the square root problem, and Password base System is secure against the well known attacks including pre-play attack, off-line dictionary attack and server comprise. A number of pass of Password base System is one, and Password base System processes the password and does not need the key. We think that Password base System is excellent for the consuming time to verify the prover.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.1
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• pp.3-11
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• 2009

Forward secrecy in an e-mail system means that the compromising of the long-term secret keys of the mail users and mail servers does not affect the confidentiality of the previous e-mail messages. Previous forward-secure e-mail protocols used the certified public keys of the users and thus needed PKI(Public Key Infrastructure). In this paper, we propose a password-based authenticated e-mail protocol providing forward secrecy. The proposed protocol does not require certified public keys and is sufficiently efficient to be executed on resource-restricted mobile devices.

• Journal of the Korea Computer Industry Society
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• v.7 no.4
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• pp.271-280
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• 2006

This study is to propose and design a protocol that offers independent authentication with no necessity of certification authority using password between participants in RS_RCCS(Relay Service-based Remote Computing Control System). In RS_RCCS without authentication center that remote service requesters have mutual authentication with many service managers, there needs for a protocol protected from password attacks. Hereupon, this study is to offer an efficient authentication setting and a protocol for RS_RCCS and helpful for the usefulness of resource management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.6
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• pp.333-340
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• 2014

Despite the security weakness of reusing passwords, many Internet users are likely to use a single ID and password on various sites to avoid the inconvenience of remembering multiple credentials. This paper proposes a scheme for securely storing, retrieving, and updating randomly chosen (ID, password) pairs by using smart cards as secure and portable storages. The scheme makes a user free from remembering her (ID, password) pairs for Internet accesses. By splitting and scattering the (ID, password) pairs of a user across the user's smart card memory and a remote server's storage, it can protect the logon credentials even from the theft or loss of the smart card. Also, a user, if deemed necessary, can issue and let the server to delete all information belonging to the user. Hence even an attacker who cracked the smart card memory would not be able to obtain any (ID, password) pair of the victim thereafter. The scheme requires a user to input a site information and pass-phrase to her smart card to obtain the logon credentials, but it should be an acceptable overhead considering the benefits of not remembering the freely chosen (ID, password) pairs at all.

• 한국지형공간정보학회:학술대회논문집
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• 2002.03a
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• pp.137-144
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• 2002

본 연구에서는 KOMPSAT-1호 EOC 위성영상으로 구성한 스트립영상과 영상의 헤더 정보를 이용하여 3차원 위치결정 모델링을 수행하여 그 정확도를 평가하였다. 스트립영상은 동일한 패스를 촬영한 단영상들을 연속적으로 접합시켜 구성하였다. 이 방법은 접근가능지역에서 기준점으로 오차보정을 실시한 후 비접근지역으로 연결되는 스트립영상을 기준점 필요 없이 위치결정을 할 수 있는 방법으로 비접근지역에 대한 지형정보 취득에 효과적인 방법으로 판단하였다.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.119-133
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• 1998

To implement full automation in pipe welding, it si most important to develop special sensors and their related systems which act like human operator when detecting irregular groove conditions. In this study, an automatic pipe Gas Metal Arc Welding (GMAW) system was proposed to full control pipe welding procedure with intelligent sensor systems. A five-axes manipulator was proposed for welding torch to automatically access to exact welding position when pipe size and welding angle were given. Pool status and torch position were measured by using a weld-pool image monitoring and processing technique in root-pass welding for weld seam tracking and weld pool control. To overcome the intensive arc light, pool image was captured at the instance of short circuit of welding power loop. Captured image was processed to determine weld pool shape. For weld seam tracking, the relative distance of a torch position from the pool center was calculated in the extracted pool shape to move torch just onto the groove center. To control penetration of root pas, gap was calculated in the extracted pool image, and then weld conditions were controlled for obtaining appropriate penetration. welding speed was determined with a fuzzy logic, and welding current and voltage were determined from a data base to correspond to the gap. For automatic fill-pass welding, the function of human operator of real time weld seam control can be substituted by a sensor system. In this study, an arc sensor system was proposed based on a fuzzy control logic. Using the proposed automatic system, root-pass welding of pipe which had gap variation was assured to be appropriately controlled in welding conditions and in torch position by showing sound welding result and good seam tracking capability. Fill-pass welding by the proposed system also showed very successful result by tracking along the offset welding line without any control of human operator.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3597-3605
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• 1999

We introduce a new satellite Conditional Access System(CAS) that a subscriber could watch a pay-TV knowing only his or her identity and password, without using a smart card. For this new system, two password-based protocols are presented which not only share a session key and authenticate each other but also download an authorization key. This system has some merits: First, compared with current systems, it reduces the amount of computations by eliminating the AK-encryption module in SMS(Subscriber Management System) and simplifying the receiver's CW-decryption process. Second, since this system does not need an expensive Card Adaptive Device(CAD), it can reduce costs. finally it provides descrambler independence allowing it to be used through any TV set-top box that includes a descrambler, unlike the current system that a descrambler is linked with a smart card.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.4
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• pp.103-112
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• 2004

This paper suggests the way to realize smart card security system by using handwritten signature instead of a password which is traditionally used for user authentication. Because of the familiarity of signature we don't need to try to remember the password and signature is difficult to be used by guess or illegal forced situation. The feature data of handwritten signature is large, so we designed COS which is consist of special commands for processing user's handwritten signature data, user authentication, and basic commands based on ISO 7816-3. Also protocol among user, smart card terminal and DB server is designed. In registration process, the feature data of user signature is saved in both a DB server and a smart card. User authentication is processed by comparing the user signature and the saved feature data in a smart card and in a DB server. And the authentication result and hash value of signature data in DB server are transferred to smart card. During this process the authentication between DB server and user is finished. The proposed security system has more higher level of security in user authentication of smart card and it will Provide safer and more convenient security services.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.229-236
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• 2008

In this paper, re proposed scheme that it safely exchange encrypted keys without Trust Third Party(TTP) and Pre-distributing keys in ubiquitous environments. Existing paper assume that exist a TTP or already pre-distributed encrypted keys between nodes. However, there methods are not sufficient for wireless environments without infrastructure. Some existing paper try to use the Diffie-Hellman algorithm for the problem, but it is vulnerable to Replay and Man-in-the middle attack from the malicious nodes. Therefore, Authentication problem between nodes is solved by modified the Diffie-Hellman algorithm using ${\mu}TESLA$. We propose safe, lightweight, and robust pair-wise agreement algorithm adding. One Time Password(OTP) using timestamp to modified the Diffie-Hellman in ubiquitous environments, and verify a safety about proposed algorithm.