A proxy signature scheme is a variation of the ordinary digital signature scheme which enables a proxy signer to generate signatures on behalf of an original signer. In this paper, we present two efficient types of proxy signature scheme. The first one is the proxy signature for warrant partial delegation combines an advantage of two well known warrant partial delegation schemes. This proposed ...

Blind signatures enable users to obtain valid signatures for a message without revealing its content to the signer. This paper presents a new blind signature scheme, i.e. identity-based blind signature scheme with message recovery. Due to the message recovery property, the new scheme requires less bandwidth than the identitybased blind signatures with similar constructions. The scheme is based ...

We analyse the legal requirements that digital signature schemes have to fulfil to achieve the Statutory Trust granted by the EU electronic signature laws (“legally equivalent to hand-written signatures”). Legally, we found that the possibility to detect subsequent changes is important for the Statutory Trust. However, detectability was neither adequately nor precisely enough defined in the tec...

As modern cryptographic schemes rely their security on the secrecy of the private keys used in them, exposing such keys results in a total loss of security. In fact, attackers have been developing various techniques to seize the secret keys rather than to cryptanalyze the underlying cryptographic primitives. Digital signature schemes, which are widely employed in many applications, are not an e...

In this paper we construct a practical group blind signature scheme. Our scheme combines the already existing notions of blind signatures and group signatures. It is an extension of Camenisch and Stadler’s Group Signature Scheme [5] that adds the blindness property. We show how to use our group blind signatures to construct an electronic cash system in which multiple banks can securely distribu...

Proxy signatures are very useful tools when one needs to delegate his/her signing capability to other party. After Mambo et al.’s first scheme was announced, many proxy signature schemes and various types of proxy signature schemes have been proposed. Due to the various applications of the bilinear pairings in cryptography, there are many IDbased signature schemes have been proposed. In this pa...

Transitive signature, motivated by signing vertices and edges of a dynamically growing, transitively closed graph, was first proposed by Micali and Rivest. The general designing paradigm proposed there involved a underlying standard signature scheme, which is required to be existentially unforgeable against adaptive chosen message attacks. We show that the requirement for the underlying signatu...

Group signature and blind signature are very important primitives in cryptography. A group signature scheme allows a group member to sign messages anonymously on behalf of the group and a blind signature scheme can ensure anonymity of the sender of a message. Recently, S. Xia and J. You [14] proposed a group signature scheme with strong separability in which the revocation manager can work with...

In real life, one requires signatures to be from people who fulfill certain criteria, implying that they should possess specific attributes. For example, Alice might want a signature from an employee in Bobs company who is a member in the IT staff, a senior manager within the biometrics team or at least a junior manager in the cryptography team. In such a case an Attribute Based Group Signature...

Digital signature scheme is an important research topic in cryptography. An ordinary digital signature scheme allows a signer to create signatures of documents and the generated signatures can be verified by any person. A proxy signature scheme, a variation of ordinary digital signature scheme, enables a proxy signer to sign messages on behalf of the original signer. To be used in different app...