In current proxy signature schemes, an original signer delegates her signing capability to a proxy signer, and then the proxy signer can sign messages on behalf of the original signer. Although these schemes have succeeded in proxy delegations, they share a common problem. That is, a verifier cannot ascertain that a proxy signature was signed by the proxy signer during the valid delegation peri...

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...

In this article, we show that the Chien et al. s partially blind signature scheme based on RSA public cryptosystem could not meet the untraceability property of a blind signature. 2002 Elsevier Inc. All rights reserved.

Abstract A (t, n) threshold proxy signature scheme enables an original signer to delegate the signature authority to a proxy group of n member such that t or more than t proxy signers can cooperatively sign messages on behalf of the original signer. In the paper, we review the security of some nonrepudiable threshold proxy signature schemes with known signers. We show that Sun’s threshold proxy...

Voting is a way for a voter to make a decision or express an opinion or to choose a candidate. E-voting (Electronic Voting) refers to both the electronic means of casting a vote and the electronic means of counting and publishing that votes. The E voting system has some specific advantages as compared to the traditional voting system. In this paper, a secure and efficient e-voting protocol is p...

The concept of ring signature was introduced by Rivest, Shamir and Tauman. This signature is considered to be a simplified group signature from which identity of signer is ambiguous although verifier knows the group to which signer belong. In this paper we introduce a new proxy ring signature scheme.

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...

The present e-payment schemes permit anonymity property to protect customer privacy. However, the majority of these schemes have not offered a non-denial property. For example, several difficulties subsist in the schemes such as repudiation, loss, abuse, theft, and overspend-tracing. This article suggests an e-payment scheme wherein a temporary anonymous public key is embedded in a partial blin...

We propose a novel cryptographic primitive called conditional blind signatures. Our primitive allows a user to request blind signatures on messages of her choice. The signer has a secret Boolean input which determines if the supplied signature is valid or not. The user should not be able to distinguish between valid and invalid signatures. A designated verifier, however, can tell which signatur...

A proxy signature scheme allows an entity to delegate its signing power to another entity. Since the notion of proxy signatures was first introduced, many proxy signature schemes and various extensions have been considered. As an example, the notion of threshold proxy signature or proxy multi-signature was introduced as a group-oriented variant. In this paper, we show that some threshold proxy ...