A blind signature scheme is a cryptographic primitive in which a user can obtain a signature from the signer without revealing any information about message signature pair. Blind signatures are used in electronic payment systems, electronic voting machines etc. The anonymity of blind signature scheme can be misused by criminals by money laundering or by dubious money. To prevent these crimes, t...

Malleable signature schemes (MSS) enable a third party to alter signed data in a controlled way, maintaining a valid signature after an authorized change. Most well studied cryptographic constructions are (1) redactable signatures (RSS), and (2) sanitizable signatures (SSS). RSSs allow the removal of blocks from a signed document, while SSSs allow changing blocks to arbitrary strings. We rigoro...

Designated confirmer signatures, initially introduced by Chaum in 1994, eliminated the undeniable signature shortcoming in which the signature can only be verified through the cooperation of the original signer. This paper proposes several practical constructions to multiple designated confirmer signature schemes. We employ the messagedependent proof of equality of the discrete logarithm and tr...

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...

This paper proposes a new ecient signature scheme from bilinear maps that is secure in the standard model (i.e., without the random oracle model). Our signature scheme is more eective in many applications (e.g., blind signatures, group signatures, anonymous credentials etc.) than the existing secure signature schemes in the standard model such as the Boneh-Boyen [6], Camenisch-Lysyanskaya [10],...

In this paper, we reinvestigate the security analysis of blind signature scheme over braid groups proposed by Verma in 2008. A blind signature scheme is a cryptographic primitive used for e-commerce for getting a signature from the signer without revealing any information about its contents. These schemes are especially used in e-transactions, e-votings, DRM systems, etc. The security of blind ...

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 distribut...

Ring signatures allow a signer to anonymously sign a message on behalf of a set of arbitrarily chosen signers called a “ring”. Blind signatures, on the other hand, allow a user to obtain a signature on a message while maintaining the privacy of the message. Blind ring signatures combine properties of both primitives and hence provide a strong notion of anonymity where the privacy of both the id...

Using Schnorr’s digital signature (DS) scheme as the underlying scheme there is designed the collective DS protocol. In the proposed collective DS protocol the signature is formed simultaneously by all signers, therefore using this protocol leads to natural solution of the problem of signing simultaneously a contract. Using the proposed collective DS protocol the blind collective DS protocol ha...