Ring signature scheme is a cryptographic construct that enables a signer to sign on behalf of a group of n different people such that the verifier can only ensure someone in the group signed, but not exactly whom. Ring signatures are utilized in many security applications. It is tricky to deploy multi-user cryptographic construct due to the complexity involved by certificates. Specifically, rin...

Multi-Designated Verifier Signature (MDVS) is a privacy-oriented signature scheme in which the signature produced can only be verified by a specific set of users. A generic MDVS scheme was proposed recently, which can be constructed from some ring signature schemes and a secure multi-party computation (SMC) protocol. In this paper, we try to remove the requirement of the costly SMC. We propose ...

Conventionally, the unforgeability of ring signature schemes is defined in an ideal environment where the attackers cannot access any information about the secret keys of the signers. This assumption is too strong to be satisfied in the real world since the cryptographic operations involves the secret key information leakage in various ways due to power/time consumption difference in operations...

In this work, we present a generic framework for constructing efficient signature schemes, ring signature schemes, and identity based encryption schemes, all in the standard model (without relying on random oracles). We start by abstracting the recent work of Hohenberger and Waters (Crypto 2009), and specifically their “prefix method”. We show a transformation taking a signature scheme with a v...

Attribute-based signatures allow a signer owning a set of attributes to anonymously sign a message w.r.t. some signing policy. A recipient of the signature is convinced that a signer with a set of attributes satisfying the signing policy has indeed produced the signature without learning the identity of the signer or which set of attributes was used in the signing. Traceable attribute-based sig...

Lin-Wu’s ID-based ring signature scheme from bilinear pairings is unreasonable. In this paper, we improve it, and obtain a reasonable ID-based ring signature scheme from bilinear pairings.

A credential system is a system in which users can obtain credentials from organizations and reveal possession of these credentials. This system is called anonymous when transactions carried out by the same user cannot be linked. In this paper we are describing few such credential systems. Nymble is a credential system in which servers themselves can blacklist misbehaving users, and thus blocks...

Ring signatures, first introduced by Rivest, shamir, and Tauman, enable a user to sign a message so that a ring of possible signers (of which the user is a member) is identified, without revealing exactly which member of that ring actually generated the signature. In contrast to group signatures, ring signatures are completely “ad-hoc” and do not require any central authority or coordination am...

In this paper, we construct an anonymous and decentralized cryptocash system which is secure in the quantum computation model. In order to achieve that, a linkable ring signature based on the ideal lattice is proposed. The size of a signature in our scheme is O(logN), where N is the cardinality of the ring. The framework of our cryptocash system follows that of CryptoNote with some modification...