Optional Security Is Not An Option
Google
This document explores the common properties of optional security protocols and extensions, and notes that due to the base-rate fallacy and general issues with coordinated deployment of protocols under uncertain incentives, optional security protocols have proven difficult to deploy in practice. This document defines the problem, examines efforts to add optional security for routing, naming, and end-to-end transport, and extracts guidelines for future efforts to deploy optional security protocols based on successes and failures to date.