Proxy signature schemes can be used in many business applications such as when the original signer is not present to sign important documents. Any proxy signature scheme has to meet the identifiability, undeniability, verifiability and unforgeability security requirements. In some conditions, it may be necessary to protect the proxy signer’s privacy from outsiders or third parties. Recently, se...

Delegation of rights is a common practice in the real world. We present two identitybased threshold proxy signature schemes, which allow an original signer to delegate her signing capability to a group of n proxy signers, and it requires a consensus of t or more proxy signers in order to generate a valid signature. In addition to identity-based scheme, privacy protection for proxy singers and s...

Proxy signature helps the proxy signer to sign messages on behalf of the original signer. It is very useful when the original signer (e.g. the president of a company) is not available to sign a specific document. If the original signer can not forge valid proxy signatures through impersonating the proxy signer, it will be robust in a virtual environment; thus the original signer can not shift a...

Multi-proxy signature allows an original signer authorizing a proxy group as his proxy agent and only the cooperation of all proxy signers in the group can create a proxy signature on behalf of the original signer. Recently, Jin and Wen defined a formal model of certificateless multi-proxy signature and proposed a concrete scheme. They claimed that their scheme is provably secure in their secur...

This paper proposes an improved RSA-based threshold proxy signature scheme. The proposed scheme satisfies the necessary security requirements of proxy signature such as verifiability, unforgeability, threshold property and identifiability. The proposed scheme does not require any secure channel to deliver the proxy keys any more. Introduction A proxy signature scheme involves three entities: an...

A substantial portion of web traffic consists of queries to database web servers. Unfortunately, a common technique to improve web scalability, proxy caching, is ineffective for database web servers because existing web proxy servers cannot cache queries. To address this problem, we modify a recently proposed enhanced proxy server, called an active proxy, to enable Active Query Caching. Our app...

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 two nonrepudiable threshold proxy signature schemes. We show that Tzeng et al.’s threshold proxy signature scheme is...

In a nominative proxy signature scheme, an original singer delegates his signing power to a proxy signer, who generates a nominative signature on behalf of the original signer. In a nominative proxy signature scheme, only the nominee can verify the signature and if necessary, only the nominee can prove its validity to the third party. In this paper, we first classify the nominative proxy signat...