Browsing by Author "Ho, Tzu-Hsin"

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Group Access Control with Blacklist for Data Dissemination in Mobile Opportunistic Networks
(2013)
Ho, Tzu-Hsin
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Yi, Chih-Wei
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
In mobile opportunistic networks, security is a major concern in consequence of store-carry-and-forward data dissemination. To guarantee that messages can be only accessed by authorized users, access control is a necessity. Fuzzy-IBE that has been proposed can provide group access control. In addition, if a sender wants to expose his/her message only to some members of his/her group, Fuzzy-IBE can provide a whitelist mechanism to further indicate which users in the group can access the data. Because overhead linearly increases with respect to the length of the whitelist, this mechanism is not sufficiently scalable as the whitelist becomes larger. In this work, we propose a Fuzzy-IBE based negative access control scheme (NAC) that allows users to selectively exclude specific members from accessing data dynamically. NAC, which does not require intensive calculation in mobile devices, is suitable for mobile opportunistic networks.
RAKA: Revocable Authenticated Key Agreement System for Mobile Social Networks
(2016-05)
Ho, Tzu-Hsin
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Shieh, Shiuhpyng Winston
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Mobile social networks (MSNs) provide users with potential indirect relationships such as friends of friends and similar transitive relationships. However, adversaries may be involved in potential relationships, the trustworthiness of the relationships must be ensured. Thus, the disclosure of private information must be well controlled, and users have to be authenticated. In this paper, we propose a revocable authenticated key agreement system (RAKA), which does not require intensive computation for authentication in MSNs. RAKA not only provides a simple rekeying process but also aggregates multiple successive private key update operations into a single rekeying process. The proposed revocation method incurs low communication overhead on mobile devices using a single message broadcast. RAKA is proved to be resilient against malicious attacks.
Simple-Yet-Efficient Construction and Revocation of Group Signatures
(2015-08-01)
Ho, Tzu-Hsin
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Yen, Li-Hsing
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Tseng, Chien-Chao
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資訊工程學系
;
Department of Computer Science
Group signatures are typically used authenticate the signer of message while preserving the privacy of the signer. Group signature should be minimized to reduce potential communication overhead. We propose a novel short group signature scheme that generates constant-size group public key and constant-size group signature. The scheme, using pairing-friendly elliptic curves, is efficient in construction. We give the security proof under XDH and ECDL hardness assumptions in the BMW model. Furthermore, we propose two group membership revocation methods which provide revocation information only to verifiers. One revocation method exposes partial private key of revoked users, which requires less revocation information. The other revocation method includes mixed private key information without revealing the real private keys of revoked users. This method is simple in revocation check.