Browsing by Author "Tsai, Jia-Lun"

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Convertible multi-authenticated encryption scheme with one-way hash function
(2009-03-27)
Tsai, Jia-Lun
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數位內容製作中心
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Center for Digital Content Production
To send the message to the recipient securely, authenticated encryption schemes were proposed. In 2008, Wu et al. [T.S, Wu, C.L. Hsu, K.Y. Tsai, H.Y. Lin, T.C. Wu. Convertible multi-authenticated encryption scheme, Information Sciences 178 (1) 256-263.] first proposed a convertible multi-authenticated encryption scheme based on discrete logarithms. However, the author finds that the computational complexity of this scheme is rather high and the message redundancy is used. To improve the computational efficiency and remove the message redundancy. the author proposes a new convertible multi-authenticated encryption scheme based oil the intractability of one-way hash functions and discrete logarithms. As for efficiency, the computation cost of the proposed scheme is smaller than Wu et al.'s scheme. (C) 2008 Elsevier B.V. All rights reserved.
EFFICIENT CONVERTIBLE MULTI-AUTHENTICATED ENCRYPTION SCHEME WITHOUT MESSAGE REDUNDANCY OR ONE-WAY HASH FUNCTION
(2010-09-01)
Tsai, Jia-Lun
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Wu, Tzong-Sun
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Lin, Han-Yu
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Lee, Jong-Eao
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應用數學系
A convertible multi-authenticated encryption (CMAE) scheme providing confidentiality, authenticity and non-repudiation properties allows a designated recipient to recover and verify an authenticated message which is signed by multiple signers. The recipient has the ability to further prove the dishonesty of signers to any third party if they repudiate their signature latter. In 2008, Wu et al. first proposed a CMAE scheme based on. discrete logarithms, but the computational complexity of their scheme is rather high and the message redundancy is required. To improve the performance and remove the message redundancy, Tsai adopted one-way hash functions (such as MD5) to propose a new scheme. In 2005, however, MD5 was cracked by Wang and Yu, which indicates that the schemes using one-way hash functions might turn out to be vulnerable to such an attack. This paper proposes a new efficient CMAE scheme. Neither the one-way hash, function nor the message redundancy is employed in the proposed scheme. The scheme not only preserves the advantages of Wu et al. 's, but also outperforms their scheme. With low computational cost, our proposed scheme can be practically implemented.
Efficient multi-server authentication scheme based on one-way hash function without verification table
(2008-05-01)
Tsai, Jia-Lun
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數位內容製作中心
;
Center for Digital Content Production
Following advances in network technologies, an increasing number of systems have been provided to help network users via the Internet. In order to authenticate the remote users, password-based security mechanisms have been widely used. They are easily implemented, but these mechanisms must store a verification table in the server. if an attacker steals the verification table from the server, the attacker may masquerade as a legal user. To solve the verification table stolen problem, numerous single server authentication schemes without verification tables have been proposed. These single authentication schemes suffer from a shortcoming. If a remote user wishes to use numerous network services, they must register their identity and password in these servers. in response to this problem, numerous related studies recently have been proposed. These authentication schemes enable remote users to obtain service from multiple servers without separately registering with each server. This study proposes an alternative multi-server authentication scheme using smart cards. The proposed scheme is based on the nonce, uses one-way hash function, and does not need to store any verification table in the server and registration center. The proposed scheme can withstand seven well known network security attacks. (C) 2008 Elsevier Ltd. All rights reserved.