Ting Yi Chang

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Recently, Yang and Shieh proposed two password authentication schemes by employing smart cards. One is a timestamp-based password authentication scheme and the other is a nonce-based password authentication scheme. In 2002, Chan and Cheng pointed out that Yang and Shieh’s timestamp-based password authentication scheme was vulnerable to the forgery attack.(More)
Lin and Wu [IEE Proc. Comput. Digit. Tech. 146 (1999) 264] have proposed an efficient ðt; nÞ threshold verifiable multi-secret sharing (VMSS) scheme based on the factorization problem and the discrete logarithm modulo a large composite problem. In their scheme, the dealer can arbitrarily give any set of multiple secrets to be shared, and only one reusable(More)
In 1999, Tseng and Jan [Comput. Commun. 22 (1999) 749] proposed two conference key distribution systems (CKDS) with user anonymity based on the discrete logarithm problem and the interpolating properties of polynomials. Their first CKDS scheme uses a one-way hash function to hide the identities of the participants and to protect each participant’s common(More)
There are occasions when some people carry their portable devices to a hotel room or office to hold a short-term conference over wireless networks. This paper designs a user-anonymous and short-term conference key distribution system to ensure secure communications over an open channel and to protect the identities of the users. Further, linker-layer(More)
In this paper, we shall propose a (t, n) threshold signature with (k, l) threshold-shared verification to be used in a group-oriented cryptosystem without a shared distribution center (SDC). In this scheme, any t participants can represent a group (signing group) to sign a message, and any k participants can represent another group (verifying group) to(More)
He and Dawson proposed a multi-stage secret sharing scheme based on one-way function. In that scheme, many secrets are reconstructed stage-by-stage in the dealer's predetermined order, and only one secret shadow is kept by every participant. When all the secrets have been reconstructed, the dealer needs not redistribute fresh shadows to every participant.(More)
Recently, Tseng et al. proposed an improvement on Peyravian and Zunic’s protected password transmission scheme and protected changing scheme to remove some security flaws. However, as we will point out in this paper, any adversary can intercept the request for changing the password sent by a legal user and modify it with a wrong password. Furthermore, we(More)