• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.157-158
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• 2013

Data privacy and access control policies in computer clouds are a prime concerns while talking about the sensitive data. Authorized access is ensured with the help of secret keys given to a range of valid users. Granting the role access is a trivial matter but revoking user access is tricky and compute intensive. To revoke a user and making his data access ineffective the data owner has to compute new set of keys for the rest of effective users. This situation is inappropriate where user revocation is a frequent phenomenon. Time based revocation is another way to deal this issue where key for data access expires automatically. This solution rests in a very strong assumption of time determination in advance. In this paper we have proposed a mutable encryption for oblivious data access in cloud storage where the access key becomes ineffective after defined number of threshold by the data owner. The proposed solution adds to its novelty by introducing mutable encryption while accessing the data obliviously.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.3
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• pp.148-159
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• 2013

An analysis of the throughput and stability region of random access systems is currently of interest in research and industry. This study evaluated the performance of a multiuser random access channel with a retransmission gain. The channel was composed of a media access control (MAC) determined by the transmission probabilities and a multiuser communication channel characterized by the packet reception probabilities as functions of the number of packet transmissions and the collision status. The analysis began with an illustrative two-user channel, and was extended to a general multiuser channel. For the two-user channel, a sufficient condition was derived, under which the maximum throughput was achieved with a control-free MAC. For the channel with retransmission gain, the maximum steady throughput was obtained in a closed form. The condition under which the random access channel can acquire retransmission gain was also obtained. The stability region of the general random access channel was derived. These results include those of the well-known orthogonal channel, collision channel and slotted Aloha channel with packet reception as a special instance. The analytical and numerical results showed that exploiting the retransmission gain can increase the throughput significantly and expand the stability region of the random access channel. The analytical results predicted the performance in the simulations quite well.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.55-63
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• 2001

There are many information objects and users in a large company. It is important issue how to control users access in order that only authorized user can access information objects, Traditional access control models do not properly reflect the characteristics of enterprise environment. This paper proposes an improved access control model for enterprise environment. The characteristics of access control in an enterprise are examined and a task role-based access control(T-RBAC) model founded on concept of classification of tasks is introduced. T-RBAC deals with each task differently according to its class, and supports task level access control and supervision role hierarchy.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.1
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• pp.41-49
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• 2011

We designed a security improved document DRM for protecting document based military information which is transmitted in the military information system environment. The user should be could not access document which not related to his/her role and duty, and must view the only document appropriate for his/her role and security level according to the security level of document. We improved the security of document DRM by adding to the access control module in DRM server. Our system allows operation mode authorizations for the document, considering the user's role & security level and the security level of document. And it prevents indiscriminate access to the document and damage the confidentiality and integrity of information.

• International Journal of Contents
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• v.8 no.3
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• pp.79-82
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• 2012

In digital contents distribution environments, a user authentication is an important security primitive to allow only authenticated user to use right services by checking the validity of membership. For example, in Internet Protocol Television (IPTV) environments, it is required to provide an access control according to the policy of content provider. Remote user authentication and key agreement scheme is used to validate the contents accessibility of a user. We propose a novel user authentication scheme using smart cards providing a secure access to multimedia contents service. Each user is authenticated using a subset of attributes which are issued in the registration phase without revealing individual's identity. Our scheme provides the anonymous authentication and the various permissions according to the combination of attributes which are assigned to each user. In spite of more functionality, the result of performance analysis shows that the computation and communication cost is very low. Using this scheme, the security of contents distribution environments in the client-server model can be significantly improved.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.2
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• pp.177-184
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• 2009

The digital contents distribution system via network provides comfortability, usability, and diversified functions to content's users. However, for the characteristic of easy access of digital contents, the copyright infringements and indiscreet contents distribution are realized in this days. In other words, any users with the authentication key can access to copyright contents with any restrictions. To solve this problems, we proposed a user authentication mechanism which prevent indiscreet access to the digital content by using user system information. Also, to provide safe distribution of digital content, we used user's unique content authentication key.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.323-342
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• 2021

Personal health records (PHRs) is an electronic medical system that enables patients to acquire, manage and share their health data. Nevertheless, data confidentiality and user privacy in PHRs have not been handled completely. As a fine-grained access control over health data, ciphertext-policy attribute-based encryption (CP-ABE) has an ability to guarantee data confidentiality. However, existing CP-ABE solutions for PHRs are facing some new challenges in access control, such as policy privacy disclosure and dynamic policy update. In terms of addressing these problems, we propose a privacy protection and dynamic share system (PPADS) based on CP-ABE for PHRs, which supports full policy hiding and flexible access control. In the system, attribute information of access policy is fully hidden by attribute bloom filter. Moreover, data user produces a transforming key for the PHRs Cloud to change access policy dynamically. Furthermore, relied on security analysis, PPADS is selectively secure under standard model. Finally, the performance comparisons and simulation results demonstrate that PPADS is suitable for PHRs.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.17-30
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• 2006

With the wide acceptance of the Internet and the Web, volumes of information and related users have increased and companies have become to need security mechanisms to effectively protect important information for business activities and security problems have become increasingly difficult. This paper proposes a improved access control model for access control enforcement in enterprise environments through the integration of the temporal constraint character of the GT-RBAC model. sub-role hierarchies concept and PBDM(Permission Based Delegation Model). The proposed model. called Extended GT-RBAC(Extended Generalized Temporal Role Based Access Control) delegation Model. supports characteristics of GTRBAC model such as of temporal constraint, various time-constrained cardinality, control flow dependency and separation of duty constraints (SoDs). Also it supports conditional inheritance based on the degree of inheritance and business characteristics by using sub-roles hierarchies and supports permission based delegation, user to user delegation, role to role delegation, multi-step delegation and temporal delegation by using PBDM.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.90-96
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• 2002

RBAC(Role-Based Access Control) is an access control method based on the user's role and it provides more flexibility on the various computer and network security fields. But, RBAC models consider only users for roles or permissions, so for the purpose of exact access control within real application systems, it is necessary to consider additional subjects and objects. In this paper, we propose an Extended RBAC model, $ERBAC_3$, for access control of multi-level security system by adding users, subjects, objects and roles level to RBAC, which enables multi-level security control. 

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.6
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• pp.1271-1282
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• 2012

Recently, security incidents occur continuously, resulting in the leakages of a large amount of the company's confidential and private information. For these reasons, the security technologies such as the authentication and the access control in order to prevent the information leakage are attracting attention. In particular, location-based authentication that utilizes the user's current location information which is used an authentication factor. And it provides more powerful authentication by controlling the users who attempt to access and blocks internal information leakage path. However, location information must be handled safely since it is the personal information. The location based authentication scheme proposed in this paper enhances the stability of the process location information compared with existing relevant location-based authentication protocol. Also it strengthens the end-user authentication by using one-time password. In addition, the proposed scheme provides authentication to prevent information leakage and employs the concept of the user's physical access control. Resultingly, the proposed scheme can provide higher security than the previous studies, while guarantee to low communication cost.