On SDVS Sender Privacy In The Multi-Party Setting

TL;DR

This paper extends the concept of sender-privacy in strong designated verifier signature schemes from a 2-party to an n-party setting, analyzing the security implications of this generalization.

Contribution

It formalizes sender-privacy in an n-party context and evaluates when this extension enhances security or falls short.

Findings

Extension can strengthen security in some cases

Extension does not always improve security

Provides a formal framework for multi-party sender-privacy

Abstract

Strong designated verifier signature schemes rely on sender-privacy to hide the identity of the creator of a signature to all but the intended recipient. This property can be invaluable in, for example, the context of deniability, where the identity of a party should not be deducible from the communication sent during a protocol execution. In this work, we explore the technical definition of sender-privacy and extend it from a 2-party setting to an n-party setting. Afterwards, we show in which cases this extension provides a stronger security and in which cases it does not.