Burdens of Proof: Cryptographic Culture and Evidence Law in the Age of Electronic Documents

Plan of the Book

12 Chapter 1 and trivializing. Isabelle Stengers has pointed out how the delegitimation of scientists’ knowledge claims by sociologists is no less violent than that performed, for example, by scientists when they seek to debunk the supposed irrationality that drives the appreciation of scientific evidence by a court of law.28 Thus, I do not take the long-standing cryptographic controversy over the meaning of “provable security” to signal some kind of normative lapse, but rather as a symptom that after many years of reliable service, certain disciplinary commitments are in need of attention and revision. The persistent discrepancies between the breadth and depth of cryptography’s social ambitions and their actual realization would seem more than ample justification for one such attempt at diagnosis and revision. Still, a nagging concern remains: after all, the state cannot be expected to function without a stable framework for written evidence. As the birthers controversy has highlighted, the legitimacy of l’état de droit fundamentally depends on public faith in the origin and integrity of the documents that signify the rule of law. Is there a point then in lifting the veil on the necessarily messy circumstances of the birth of a new evidentiary paradigm? One answer might be that this project is intellectually aligned with cryptographers ’ critique of “security through obscurity,” an approach they have forcefully decried as ultimately resulting in flawed security design.29 Plan of the Book Chapter 2, “Communication in the Presence of Adversaries,” sets the stage by providing a short overview of the history of cryptographic technologies, periodized along successive “information ages.”30 In each of these periods, a dominant information and communication technology—paper, telegraph , radio, electromechanical computing, and networked computers— drives the development of cryptographic techniques and devices. By situating the development of these techniques within their social, institutional , and material context, a picture emerges that highlights some often unarticulated dimensions of the cryptographic experience, with important implications for modern cryptographic design: how the embodiment of cryptographic techniques in physical artifacts provides resources for defeating their security objectives; the logistical issues that have historically plagued the large-scale deployment of cryptographic technologies, in par- Introduction 13 ticular, the inherently difficult problem of key distribution; the design trade-offs that seem to perpetually obtain between high-grade security and user-friendliness; and, given the special interest of the state in both listening to and securing important communications, the unique structural forces that have shaped the development of the field. In chapter 3, “On the Brink of a Revolution,” I analyze a turning point in the history of cryptographic innovation, the 1976 publication of Diffie and Hellman’s “New Directions in Cryptography.” The founding document of cryptography’s modern era, “New Directions” argued not only for radically new applications of cryptography for the coming age of computer networks, but also for a new paradigm of provable security based on the certification of cryptosystems through the mathematical frameworks of complexity theory and algorithmics. The invention of public-key cryptography unleashed a creative explosion in the field, the growth of a research community independent of the military and intelligence establishment, and the development of a broad research program aiming at providing all functions necessary to the integrity of electronic information, including the signatures needed to secure e-commerce transactions. In addition to these achievements, by the 1990s cryptography had also emerged as the Internet’s first native political movement and cyberlibertarianism’s most prominent voice. However, this chapter underlines how cryptography’s emerging scientific program supported a broad range of positions on the social purposes of cryptographic research, many of a more conservative bent than crypto’s well-publicized image suggested. In chapter 4, “The Equivalent of a Written Signature,” I examine the gradual crystallization of a cryptographic model for an “electronic equivalent to handwritten signatures.” The model defines both the function of signatures, that is, the provision of the three security services of identification , integrity, and non-repudiation, as well as the specific threats and adversaries these services must protect against. The market demise of public-key infrastructures provides a concrete and powerful critique of the digital signature model, in addition to a powerful reminder that key distribution remains the Achilles’ heel of any large-scale deployment of cryptographic technologies. I argue the considerable difficulties met in translating this model into a commercially successful technology point to cryptographers’ problematic relationship with the representational nature of models. In adopting the...