The Drawbridge Model of Cryptographic Communication

Abstract

This article introduces a theory and model of cryptographic communication that treats conditions of communication failure as the basis for different types of information security. Building on the metaphor that communication is a bridge when it succeeds and a chasm when it fails, cryptography serves as a kind of drawbridge to limit the audience of a message through selective communication failure. Different forms of cryptographic mediation are thus framed as arts of privation that selectively limit and divide an audience. This theoretical framework is illustrated using a model with a series of drawbridges representing distinct sources of communication failure, each of which induces distinct limits or privations depending on the manner and conditions of failure. The model’s descriptive, explanatory, and diagnostic power are illustrated through various examples in which distinct forms of communication failure are used to facilitate conditions of privileged discourse and dialogue by narrowing the dissemination of communication.