This paper introduces a new obfuscation called obfuscation of encrypted blind signature. Informally, Alice is Signer and Bob is User. Bob needs Alice to sign a message, but he does not want Alice to know what the message is. Furthermore, Bob doesn’t want anyone to know the interactive process. So we present a secure obfuscator for encrypted blind signature which makes the process of encrypted b...

Blind signature schemes, an important cryptographic primitive , are useful in protocols that guarantee the anonymity of the participants. Two new blind signature schemes based on the discrete logarithm problem are presented.

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A group signature allow any member of a group to sign on behalf of the group. A group blind signature requires that a group member signs on group’s behalf a document without knowing its content. In this paper we propose a practical coalition-resistant group blind signature scheme based on the strong RSA and the decisional Diffie-Hellman assumptions. Our scheme is an extension of the group signa...

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 ...

In a group signature [19], any group member can sign on behalf of the group while remaining anonymous, but its identity can be traced in an future dispute investigation. Essentially all state-of-theart group signatures implement the tracing mechnism by requiring the signer to escrow its identity to an Open Authority (OA) [2, 14, 4, 25, 5, 7, 24]. We call them Tracing-by-Escrowing (TbE) group si...

Group blind signatures combine anonymity properties of both group signatures and blind signatures and offer privacy for both the message to be signed and the signer. Their applications include multi-authority e-voting and distributed e-cash systems. The primitive has been introduced with only informal definitions for its required security properties. We offer two main contributions: first, we p...

A (t, n) threshold signature scheme allows t or more group members to generate signatures on behalf of a group with n members, while any t−1 or less members cannot do the same thing. In 2001, based on a variant of ElGamal digital signature scheme, Li et al. proposed two (t, n) threshold signature schemes with traceable signers. One of their schemes needs the assistance of a mutually trusted cen...

A fair blind signature scheme allows the trustee to revoke blindness so that it provides authenticity and anonymity to honest users while preventing malicious users from abusing the anonymity to conduct blackmail etc. Although plausible constructions that offer efficient tricks for anonymity revocation have been published, security, especially one-more unforgeability and revocability against ad...

How to design a blind signature based on the discrete logarithm for untraceability is still a field in need of cultivation. In this article, we shall propose a new blind signature based on the discrete logarithm problem.