Introduction: Bringing Protocols to Life (Transcript of Discussion) -- Secure Internet Voting Protocol for Overseas Military Voters -- Secure Internet Voting Protocol for Overseas Military Voters (Transcript of Discussion) -- Self-enforcing Electronic Voting -- Self-enforcing Electronic Voting (Transcript of Discussion) -- Approaches to Modelling Security Scenarios with Domain-Specific Languages -- Approaches to Modelling Security Scenarios with Domain-Specific Languages (Transcript of Discussion) -- The Casino and the OODA Loop: Why Our Protocols Always Eventually Fail -- The Casino and the OODA Loop: Why Our Protocols Always Eventually Fail (Transcript of Discussion) -- Statistical Metrics for Individual Password Strength -- Statistical Metrics for Individual Password Strength (Transcript of Discussion) -- Street-Level Trust Semantics for Attribute Authentication -- Street-Level Trust Semantics for Attribute Authentication (Transcript of Discussion) -- Analysis of Issues and Challenges of E-Voting in the UK -- Analysis of Issues and Challenges of E-Voting in the UK (Transcript of Discussion) -- Protocol Governance: The Elite, or the Mob? -- Protocol Governance: The Elite, or the Mob? (Transcript of Discussion) -- Usability Issues in Security -- Usability Issues in Security (Transcript of Discussion) -- Usable Privacy by Visual and Interactive Control of Information Flow -- Usable Privacy by Visual and Interactive Control of Information Flow (Transcript of Discussion) -- Sense-And-Trace: A Privacy Preserving Distributed Geolocation Tracking System -- Sense-And-Trace: A Privacy Preserving Distributed Geolocation Tracking System (Transcript of Discussion) -- Am I in Good Company? A Privacy-Protecting Protocol for Cooperating Ubiquitous Computing Devices -- Am I in Good Company? A Privacy-Protecting Protocol for Cooperating Ubiquitous Computing Devices (Transcript of Discussion) -- Stayin' Alive: Aliveness as an Alternative to Authentication -- Stayin' Alive: Aliveness as an Alternative to Authentication (Transcript of Discussion) -- Paul Revere Protocols -- Paul Revere Protocols (Transcript of Discussion) -- The Last Word. Secure Internet Voting Protocol for Overseas Military Voters -- Secure Internet Voting Protocol for Overseas Military Voters (Transcript of Discussion) -- Self-enforcing Electronic Voting -- Self-enforcing Electronic Voting (Transcript of Discussion) -- Approaches to Modelling Security Scenarios with Domain-Specific Languages -- Approaches to Modelling Security Scenarios with Domain-Specific Languages (Transcript of Discussion) -- The Casino and the OODA Loop: Why Our Protocols Always Eventually Fail -- The Casino and the OODA Loop: Why Our Protocols Always Eventually Fail (Transcript of Discussion) -- Statistical Metrics for Individual Password Strength -- Statistical Metrics for Individual Password Strength(Transcript of Discussion) -- Street-Level Trust Semantics for Attribute Authentication -- Street-Level Trust Semantics for Attribute Authentication (Transcript of Discussion) -- Analysis of Issues and Challenges of E-Voting in the UK -- Analysis of Issues and Challenges of E-Voting in the UK (Transcript ofDiscussion) -- Protocol Governance: The Elite, or the Mob? -- Protocol Governance: The Elite, or the Mob? (Transcript of Discussion) -- Usability Issues in Security -- Usability Issues in Security (Transcript of Discussion) -- Usable Privacy by Visual and Interactive Control of Information Flow -- Usable Privacy by Visual and Interactive Control of Information Flow (Transcript of Discussion) -- Sense-And-Trace: A Privacy Preserving Distributed Geolocation Tracking System -- Sense-And-Trace: A Privacy Preserving Distributed Geolocation Tracking System (Transcript of Discussion) -- Am I in Good Company? A Privacy-Protecting Protocol for Cooperating Ubiquitous Computing Devices -- Am I in Good Company? A Privacy-Protecting Protocol for Cooperating Ubiquitous Computing Devices (Transcript of Discussion) -- Stayin' Alive: Aliveness as an Alternative to Authentication -- Stayin' Alive: Aliveness as an Alternative to Authentication (Transcript of Discussion) -- Paul Revere Protocols -- Paul Revere Protocols (Transcript of Discussion) -- The Last Word.

This book constitutes the thoroughly refereed post-workshop proceedings of the 20th International Workshop on Security Protocols, held in Cambridge, UK, in April 2012. Following the tradition of this workshop series, each paper war revised by the authors to incorporate ideas from the workshop, and is followed in these proceedings by an edited transcription of the presentation and ensuing discussion. The volume contains 14 papers with their transcriptions as well as an introduction, i.e. 29 contributions in total. The theme of the workshop was "Bringing protocols to life".