Mesh Signatures : How to Leak a Secret with Unwitting and Unwilling Participants

We define the mesh signature primitive as an anonymous signature similar in spirit to ring signatures, but with a much richer language for expressing signer ambiguity. The language can represent complex access structures, and in particular allows individual signature components to be replaced with complete certificate chains. Because withholding one’s public key from view is no longer a shield against being named as a possible cosignatory, mesh signatures may be used as a ring signature with compulsory enrollment. We give an efficient construction based on bilinear maps in the common random string model. Our signatures have linear size, achieve everlasting perfect anonymity, and reduce to very efficient ring signatures without random oracles as a special case. We prove non-repudiation from a mild extension of the SDH assumption, which we introduce and justify metic-