Designated confirmer signatures

This paper introduces a new kind of signature authentication and gives practical protocols that implement it. The technique can be used in ways that approach the functionality of known techniques, such as ordinary digital signatures and zero-knowledge proofs. But more importantly, it opens up a whole space of possibilities in between them. The technique works in essence by allowing the signer to prove to the signature's recipient that designated parties can confirm the signature without the signer. But the signer is protected, since unless sufficient designated parties cooperate in confirmation, the signature is no more convincing than any other number.