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Chang L.-P.,National Taiwan University of Science and Technology | Wu T.-C.,National Taiwan University of Science and Technology | Wu T.-C.,Taiwan Information Security Center | Hsu C.-L.,Chang Gung University | And 2 more authors.
Journal of Internet Technology | Year: 2010

This paper presents a two level ECC-based group key agreement scheme with privacy-preservation, where a group manager can easily setup a secure protocol in a public network to let the intended group members share an authenticated session key without disclosing their identities in the subsequent communication. To protect privacy, the proposed scheme provides the property of user anonymity, an adversary can not intercept the information of intended group member's identity and use it to launch some attacks. By using self-certified public keys and based on the elliptic curve cryptosystems (ECC), the proposed scheme not only satisfies the security requirements of perfect forward secrecy, known key security (resistance to known key attacks), implicit key authentication, and key confirmation (explicit key authentication), but also achieves performance efficiency in practices. The proposed protocol can gain much efficiency in saving both the communicational cost and the computational effort as compared to previous works implemented by modular exponentiation, so it is quite suitable to be used for resource-limited mobile devices in mobile internet.


Yen C.-T.,National Taiwan University of Science and Technology | Yen C.-T.,Taiwan Information Security Center | Wu T.-C.,National Taiwan University of Science and Technology | Wu T.-C.,Taiwan Information Security Center | And 4 more authors.
IET Information Security | Year: 2010

The rapid development in electronic commerce and information technology drives the traditional physical product trading evolved to digital product trading. With the effect of the multi-agents system in the Internet environment and the promotions of Government, digital product industry grows fast. The authors proposed a digital product transaction mechanism for electronic auction in the multi-agents system environment. The research introduced a convenient platform to protect the privacies of both buyers and sellers, and track digital product further in an electronic auction environment. In addition, by using simple cryptography techniques supplemented with encryption, the authors ensure the security of information transactions, thereby providing a mechanism of safe and fair digital product electronic auction. © 2010 The Institution of Engineering and Technology.


Lin Y.-C.,National Taiwan University of Science and Technology | Wu T.-C.,Taiwan Information Security Center | Wu T.-C.,National Taiwan University of Science and Technology | Tsai J.-L.,National Taiwan University of Science and Technology
Journal of Information Science and Engineering | Year: 2013

This paper proposes a novel ID-based aggregate proxy signature scheme that realizes a warrant-based delegation for an original signer to transfer his/her signing power to a given set of proxy signers. Our proposed scheme allows n distinct proxy signers to sign n distinct messages in such a way that these n individual signatures can be aggregated into a single one without expansion. In the practical applications, such specific kind of aggregate signatures is significantly applausive for enforcing the delegation of authority with both bandwidth and computation savings. Our proposed scheme requires constant bilinear pairing operations for signature verification. Besides, the size of the aggregate proxy signature is the same as that of each of the individual proxy signatures, regardless of the number of participant proxy signers has involved. We also formally sketch the security model of our proposed scheme and show that it is secure against the chosen message attacks under the computational Diffie-Hellman (CDH) assumption.

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