SoK: Securing Email -- A Stakeholder-Based Analysis (Extended Version)

TL;DR

This paper analyzes the complex landscape of secure email solutions by examining stakeholder interests, evaluating cryptographic components, and highlighting the challenges in achieving universal, secure, and interoperable email communication.

Contribution

It provides a stakeholder-based analysis of secure email evolution, evaluates cryptographic building blocks, and discusses why a universal solution remains elusive.

Findings

Current solutions are fragmented and stakeholder-specific.

Vulnerable users are poorly served by existing secure email methods.

Secure messaging is complementary but not a substitute for secure email.

Abstract

While email is the most ubiquitous and interoperable form of online communication today, it was not conceived with strong security guarantees, and the ensuing security enhancements are, by contrast, lacking in both ubiquity and interoperability. This situation motivates our research. We begin by identifying a variety of stakeholders who have an interest in the current email system and in efforts to provide secure solutions. We then use the tussle among stakeholders to explain the evolution of fragmented secure email solutions undertaken by industry, academia, and independent developers. We also evaluate the building blocks of secure email -- cryptographic primitives, key management schemes, and system designs -- to identify their support for stakeholder properties. From our analysis, we conclude that a one-size-fits-all solution is unlikely. Furthermore, we highlight that vulnerable users are not well served by current solutions, account for the failure of PGP, and argue that secure messaging, while complementary, is not a fully substitutable technology.