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In the (t, n) proxy signature scheme, the signature, originally signed by a signer, can be signed by t or more proxy signers out of a proxy group of n members. Recently, an efficient nonrepudiable threshold proxy signature scheme with known signers was proposed by H.-M. Sun. Sun's scheme has two advantages. One is nonrepudiation. The proxy group cannot deny(More)
Over the past few years a number of research papers about reversible watermarks has been produced. Reversible wa-termarking is a novel category of watermarking schemes. It not only can strengthen the ownership of the original media but also can completely recover the original media from the watermarked media. This feature is suitable for some important(More)
The micro-payment system is an important technique in electronic commerce. The high-value payment system is not suitable for a micro-payment system because the requirements are di€erent. To meet sucient security for all participants in electronic commerce , a micro-payment system makes it possible to make small payment through electronic communication(More)
Electronic sealed-bid auction schemes usually have a common drawback, the third party (auction host) can conspire with a malicious bidder to leak all bidding prices before the opening stage. It results in the malicious bidder wining the auction with an optimal bidding price. Recently, Liaw et al. proposed an auction protocol for electronic online bidding in(More)
Conventional remote password authentication schemes allow a serviceable server to authenticate the legitimacy of a remote login user. However, these schemes are not used for multiserver architecture environments. We present a remote password authentication scheme for multiserver environments. The password authentication system is a pattern classification(More)
Remote user authentication is used to validate the legitimacy of a remote login user. Conventional user authentication schemes are suited to solve the privacy and security problems for the single client/server architecture environment. However, the use of computer networks and information technology has grown spectacularly. More and more network(More)