We propose a model for fair electronic cash issued by multiple banks for the first time. A scheme of electronic cash with multiple banks in which a user can be traced is presented by using the improved group signature scheme of Cam97[4] and the group blind signature scheme of Lys98[16]. A weakness in the design of withdrawal and payment protocols of electronic cash using the existing group sign...

At Crypto’99, Dr Coron, Naccache, and Stern presented a signature forgery strategy of the RSA digital signature scheme. The attack is valid on Chaum’s blind signature scheme, which has been applied to many practical applications such as electronic cash and voting. In this paper we propose a method to inject a randomizing factor into a message when it is signed by the signer in Chaum’s blind sig...

Blind signature is the concept to ensure anonymity of e-coins. Untracebility and unlinkability are two main properties of real coins, which require mimicking electronically. Whenever a user is permitted to spend an e-coin, he is in need to ful ll above requirements of blind signature. In this paper a proxy blind signature scheme is given with which a proxy is able to make proxy blind signature ...

Proxy signature is a signature that an original signer delegates his or her signing capability to a proxy signer, and then the proxy signer creates a signature on behalf of the original signer. However, Sun et al. [7] showed that the proxy and multi-proxy signatures of Lee et al. [3], and the strong proxy signature scheme with proxy signer privacy protection of Shum et al. [6] are not against t...

Privacy homomorphisms, encryption schemes that are also homomorphisms relative to some binary operation, have been studied for some time, but one may also consider the analogous problem of homomorphic signature schemes. In this paper we introduce basic definitions of security for homomorphic signature systems, motivate the inquiry with example applications, and describe several schemes that are...

A proxy blind signature scheme is the combination of proxy signature and blind signature scheme. In 2009,Verma proposed a proxy blind signature scheme over braid groups. Verma claimed that the proposed scheme is secure against all possible security lapses and also satisfy all essential security attributes.This paper analyzes Verma’s proposed scheme and found that this scheme suffers with the se...

A fair blind signature is a blind signature with revocable anonymity and unlinkability, i.e., an authority can link an issuing session to the resulting signature and trace a signature to the user who requested it. In this paper we first revisit the security model for fair blind signatures given by Hufschmitt and Traoré in 2007. We then give the first practical fair blind signature scheme with a...

Using the digital signature (DS) scheme specified by Belarusian DS standard there are designed the collective and blind collective DS protocols. Signature formation is performed simultaneously by all of the assigned signers, therefore the proposed protocols can be used also as protocols for simultaneous signing a contract. The proposed blind collective DS protocol represents a particular implem...

Structure-preserving signature schemes can be very useful in the construction of new cryptographic operations like blind signatures. Recently several of these schemes have been proposed. The security of signature-preserving signature schemes is still proved by hand, which can be a laborious task. One of the ways to prove security of these schemes algebraic analysis can be used. We present an ap...

In this paper, we propose a group-oriented fair blind (t; n) threshold signature scheme based on the discrete logarithm problem. By the scheme, any t out of n signers in a group can represent the group to sign fair blind threshold signatures, which can be used in anonymous e-cash systems. Since blind signature schemes provide perfect unlinkability, such e-cash systems can be misused by criminal...