• The KIPS Transactions:PartC
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• v.14C no.1 s.111
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• pp.65-72
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• 2007

The existing RBAC models are not sufficient for managing delegations or separation of roles. Researches have been done on RBDM(Role Based Delegation Model) that deal with delegating role or permission to other users. In this paper, we divide the delegated roles into two groups: periodic and temporary delegation roles. When a role is delegated, a time period is assigned together, which is used to revoke the permission of delegated role automatically. In our model, the role of monotonic delegation by an original user can be revoked at any time in case of malicious use by the delegated user. The contribution of our model is that the malicious use of delegated role can be prohibited and security vulnerability in the role hierarchy due to role delegations can be alleviated. The proposed model, T RBDM(Time out Based RBDM) is analyzed and compared with the conventional models, such as RBDM0, RBDM1 and PBDM. Our model shows an advantage over other models in terms of security robustness.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.13-23
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• 2004

Proxy signature scheme based on delegation of warrant is studied in these days. Proxy signature is a signature scheme that the original signer delegates his signing warrant to the proxy signer, and the proxy signer creates a signature on behalf of the original signer. For using this scheme, the security for Protecting from the forgeability or misuse is necessary. There are several security requirements for using the proxy signature schemes. In this paper we suggest the proxy-register protocol scheme that original signer registers to the verifier about the proxy related information. In our scheme, verifier verifies the signature that original signer creates about the proxy information and sets the warrant of proxy signer, validity period for proxy signature and some limitation. Finally, we will show the advantages of our suggestion by comparing with the previous proxy signature schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.379-382
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• 2014

BYOD 는 다양한 기기에서 상호 운용되고, 상황에 따라 다른 접근권한을 가질 수 있다. BYOD 는 기업의 입장에서는 생산성 향상과 기기에 대한 비용 감소 등의 장점을 가지고 있다. 하지만 보안의 중대한 취약점을 가지고 있고 기업은 개인이 사용하는 각기 다른 기기들에 대해서 통제하기 힘들다는 점과 관리비용은 오히려 상승할 수도 있다는 점 등의 단점들이 부각이 되고 있다. BYOD 에 접근 가능한 권한들을 효율적으로 관리하여 접근권한 관련 설정 오류를 최소화하고, 권한이 없는 사용자의 접근을 차단하기 위한 'BYOD 환경에 적합한 접근 제어 기술'이 요구된다. 따라서 본 논문에서는 BYOD 시장의 급속한 발달과, 스마트 폰 하드웨어,소프트웨어의 발전에 맞춰 RBAC(Role Based Access Control)을 이용한 접근제어 방법을 제안한다. 이는 사용자 특성, 역할 특성, 시스템 특성에 따라 권한 활성화 제약이 가능하며, 권한 위임과 권한 상속 시에 시간, 위치정보, 위기 상황 발생여부에 따라 제약을 할 수 있다.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2001.05a
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• pp.107-110
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• 2001

역할기반 접근제어는 지금까지 사용되었던 기존의 임의적 접근제어나 강제적 접근제어를 개선해서 여러 분야에 적용시키기 위해서 많은 연구의 대학이 되어왔다. 이 접근제어 방법은 역할과 사용자, 그리고 권한 사이의 관계를 정의하고, 역할계층을 통해서 역할에 따른 사용자의 권한 관리를 효율적으로 할 수 있도록 있다. 따라서, 본 논문에서는 기존의 역할계층을 현실세계에서의 조직체계에 적용시키는 것에는 문제가 있다. 따라서, 본 논문에서는 기존의 역할계층에서 위임과 상속의 문제점을 제시하고, 새로운 접근방식의 위임과 상속을 제안한다.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.63-70
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• 2012

To ensure privacy of individual information in remote healthcare service, health data should be protected through a secure technology such as encryption scheme. Only user who delegated decryption right can access to sensitive health data and delegator needs capability for revocating access privilege. Recently, in ubiquitous environment, CP-ABTD(Ciphertext-Policy Attribute-Based Threshold Decryption with Flexible Delegation and Revocation of User Attributes) which extends CP-ABE(Ciphertext-Policy Attribute-Based Encryption) has been proposed for these requirements. In this paper, we construct remote healthcare monitoring system with delegation and revocation capability for attribute in CP-ABTD. Finally, we analyze collusion attack between users in our system.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.725-730
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• 2004

Separation of Duty(SOD), with delegation, is one of important security principles in access control area. The role-based access control model adopts SOD principle, but it has some problems; SOD concept is inconsistent with role hierarchy, permissions that have no relation with SOD may be restricted, and delegation may violate SOD. We propose permission-based SOD model on role-based access control. We establishes SOD as a set of permissions instead of role level SOD. Furthermore we propose a principle of role activation. It solves SOD problems of RBAC and supports easy implementation of SOD policy.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.8
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• pp.465-472
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• 2004

Proxy signatures is a signature scheme that an original signer delegates one's signature capability to a proxy signer, and then the proxy signer creates a signature on behalf of the original signer. Delegation of authority is a common practice in the real world, in particular, it happens naturally in hierarchical groups such as company, bank and army, etc. In this paper, we propose a new dynamic multi-proxy signature scheme allowing repetitive delegations in a hierarchical group. We adopt multi-proxy signatures to enhance the security of proxy signature. In multi-proxy signatures, plural proxy signers can generate a valid proxy signature collectively on behalf of one original signer. In our scheme, the proxy group is not fixed but constructed dynamically according to some situations. Delegations are processed from higher level to lower level in the hierarchy using delegation tickets. When the original signer wants to delegate one's signature authority, the original signer generates a delegation ticket based on secret sharing and Diffie-Hellman problems. The delegation ticket is shared among proxy signers and then all the proxy signers can generate a valid proxy signature collectively by reconstructing the original signer's delegation ticket. If a certain proxy signer can not attend the proxy signature generating protocol, the proxy signer can also delegate repetitively his partial signature authority to the lower level participants, and then the proxies are constructed dynamically.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.91-96
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• 2004

Proxy signature scheme based on delegation of warrant is studied in these days. Proxy signature is a signature scheme that the original signer delegates his signing warrant to the proxy signer, and the proxy signer creates a signature on behalf of the original signer. For using this scheme, the security for protecting from the forgeability or misuse is necessary, There are several security requirements for using the proxy signature schemes. In this paper we suggest the proxy-register protocol scheme that original signer registers to the verifier about the proxy related information. In our scheme, verifier verifies the signature that original signer creates about the proxy information and sets the warrant of proxy signer, validity period for proxy signature and some limitation. Finally, we will show the advantages of our suggestion by comparing with the previous proxy signature schemes.

• Convergence Security Journal
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• v.4 no.2
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• pp.35-41
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• 2004

Proxy signature scheme based on delegation of warrant is studied in these days. Proxy signature Is a signature scheme that the original signer delegates his signing warrant to the proxy signer, and the proxy signer creates a signature on behalf of the original signer. For using this scheme, the security for protecting from the forgeability or misuse is necessary. There are several security requirements for using the proxy signature schemes. In this paper we suggest the proxy-register protocol scheme that original signer registers to the verifier about the proxy related information. In our scheme, verifier verifies the signature that original signer creates about the proxy information and sets the warrant of proxy signer, validity period for proxy signature and some limitation. Finally, we will show the advantages of our suggestion by comparing with the previous proxy signature schemes.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.212-214
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• 2012

본 논문은 P2P(Peer-To-Peer) 환경이 가지는 장점과 DRM(Digital Rights Management) 기술이 가지는 장점을 결합하여, 서비스에 참여하는 사용자가 합법적으로 컨텐츠를 재판매 할 수 있는 방법을 제공 함으로써 컨텐츠 유통을 활성화 하는 방안을 제시한다. 사용자가 중앙 서버에서 구매한 컨텐츠나 이웃 피어(Peer)에게 구매한 컨텐츠를 재판매 할 경우, 실행권한 라이선스(Rights)를 중앙 서버의 권한 발급기(Rights Issuer)가 아닌, 판매하는 피어 측에서 권한을 위임 받아 직접 발급한다. 컨텐츠를 구매하면 결재가 진행되고, 해당 이익금은 판매한 피어와 해당 컨텐츠를 구매하기까지 참여한 피어의 경로를 분석하여 이익이 재분배 된다. 이러한 이익금 재분배 과정을 통해 합법적인 컨텐츠 유통의 활성화를 기대할 수 있고, P2P 네트워크 환경이 가지는 여러 장점과 DRM 기술의 장점을 융합하여 저비용의 신뢰할 수 있는 시스템 구축이 가능할 것으로 예상된다.