Feng Hao and Peter Y A Ryan (Eds.) Real-World Electronic Voting: Design, Analysis and Deployment

Transcription

1 Feng Hao and Peter Y A Ryan (Eds.) Real-World Electronic Voting: Design, Analysis and Deployment

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3 Contents Foreword xvii Preface xxi SECTION I: SETTING THE SCENE 1 1 Software Independence Revisited Ronald L. Rivest and Madars Virza 1.1 Introduction Problem: Software complexity of voting systems The difficulty of evaluating complex software for errors The need for software-independent approaches Definition and rationale for software-independence Refinements and elaborations of software-independence Examples of software-independent approaches How does one test for software-independence? Discussion Implications for testing and certification Related issues Evidence-based elections The use of a public ledger End-to-end verifiable voting systems iii

4 iv 1.9 Program verification Verifiable computation and zero-knowledge proofs Conclusions and suggestions Guidelines for Trialling E-voting in National Elections Ben Goldsmith 2.1 Terminology Context for E-Voting International Electoral Standards Decision in Principle Decision in Principle Foundations Feasibility Study Mandate Vendor Relations Feasibility Study Committee Working Groups Issue 1 Assessment of the Current System of Voting and Counting Issue 2 Assessment of the Advantages and Disadvantages Offered by Voting Technologies Issue 3 Review of IT Security Aspects Issue 4 Determining Technical Feasibility Issue 5 Cost Benefit Analysis Issue 6 Institutional Capacity Issue 7 Legal Reform Issues Study Trips Vendor Demonstration Stakeholder Consultation Decision in Principle Pilot Project Prerequisites Pilot Project Mandate Type of Pilot Pilot Locations Solutions Being Piloted Legislation Electronic Voting Technology Specification

5 v Pilot Project Funding Pilot Project Managing the Pilot Project Procuring Electronic Voting Technologies Testing and Certification Polling and Counting Procedures Voter Education Training Stakeholder Outreach Election Day Support Observation of the Pilot Project Mandatory Audit Pilot Project Evaluation The Decision on Adoption SECTION II: REAL-WORLD E-VOTING IN NATIONAL ELECTIONS 51 3 Overview of Current State of E-voting World-wide Carlos Vegas and Jordi Barrat 3.1 Introduction The Public Nature of Elections Civic Activism Business as Usual Outdated Technologies The Political Context Voters Matter Conclusions Electoral Systems Used around the World Siamak F. Shahandashti 4.1 Introduction Some Solutions to Electing A Single Winner Some Solutions to Electing Multiple Winners

6 vi 4.4 Blending Systems Together Other Solutions Which Systems Are Good? A Theorist s Point of View Majority Rules Bad News Begins Arrow s Impossibility Theorem Gibbard Satterthwaite Impossibility Theorem Systems with Respect to Criteria A Practitioner s Point of View E-voting in Norway Kristian Gjøsteen 5.1 Introduction Elections in Norway Requirements Buying a Voting System Cryptographic Protocol Scytl s Proposal Modifications The Modified Protocol Deployment The 2011 Election The 2013 Election Concluding Remarks E-voting in Estonia Dylan Clarke and Tarvi Martens 6.1 Voting in Estonia Estonian National ID Cards The Internet Voting System System Components Normal System Operation

7 vii Auditing and Verification Capabilities Internet Voting Assumptions and Reception System Performance Practical Attacks on Real-world E-voting J. Alex Halderman 7.1 Introduction Touchscreen DREs Diebold Top to Bottom The Test of Time Around the World Internet Voting The Washington, D.C. Internet Voting System Estonia s Internet Voting System The New South Wales ivote System Conclusion SECTION III:E2E VOTING SYSTEM AND REAL-WORLD APPLICATIONS An Overview of End-to-End Verifiable Voting Systems Syed Taha Ali and Judy Murray 8.1 Introduction Security Properties of Voting Systems Vote Privacy Vote Verifiability Other Properties Conflicts and Challenges Cryptographic E2E Voting Systems Precinct-based Voting with Physical Ballots Votegrity Prêt à Voter Punchscan

8 viii Scantegrity Scratch & Vote Precinct-based Voting with Electronic Ballots MarkPledge Bingo Voting Voter Initiated Auditing VoteBox Wombat STAR-Vote DRE-i Remote Voting with Electronic Ballots Adder JCJ and Civitas Helios Pretty Good Democracy Remotegrity Non-cryptographic E2E Voting Systems ThreeBallot, VAV, and Twin Randell & Ryan s Scratch Card Voting System Aperio The Way Forward for E2E Voting Systems Technical Issues Usability Legal Framework Uptake of E2E Voting Systems Conclusion Acknowledgements Theoretical Attacks on E2E Voting Systems Peter Hyun-Jeen Lee and Siamak F. Shahandashti 9.1 Introduction Integrity Misprinted ballots attack

9 ix Trash Attack Clash Attack Flawed Mix-net Privacy Replay Attack Kleptographic Attack Pfitzmann s attack Duplicate ciphertext attack Breaking privacy without detection Coercion Forged ballot Vote against a candidate Scratch-off card attack Spoiling ballots Pay-Per-Mark & Pay-for-Receipt Conclusion Acknowledgements The Scantegrity Voting System and its Use in the Takoma Park Elections 237 Richard T. Carback, David Chaum, Jeremy Clark, Aleksander Essex, Travis Mayberry, Stefan Popoveniuc, Ronald L. Rivest, Emily Shen, Alan T. Sherman, Poorvi L. Vora, John Wittrock, and Filip Zagórski 10.1 Introduction Key Properties Outline Organization of this chapter The Punchscan Voting System Voter Experience Election Set-Up Ballot Printing and Voter Privacy The First Binding E2E Election Lessons Learned The Scantegrity II Voting System Ballot Features

10 x The Scantegrity Back-End Election Day Posting and Tallying Auditing the Results Dispute Resolution The 2009 Takoma Park Election Requirements Mock Election The Election The Remotegrity Voting System Voter Experience Security Properties Audiotegrity The Voting Process with Audiotegrity Dispute Resolution Properties Takoma Park Election, Usability Studies Related Studies Methodology Known Limitations Voter Response Observational Results Election Judge Response Study Findings Current Status of the Project Conclusions Internet voting with Helios Olivier Pereira 11.1 Introduction Helios History Election walkthrough Voting in a Helios election

11 xi Invitation to vote Submitting a ballot Election management Election creation Election tally Election audit Cast-as-intended verification Recorded-as-cast verification Tallied-as-recorded verification The use of cryptography in Helios Arithmetic and computational assumption Encryption Zero-Knowledge proofs Sigma protocols Proving honest key generation Proving correct decryption Proving ballot validity Protocol analysis Works on Verifiability Works on ballot privacy Miscellaneous works Web application perspective The browser interface Cryptography in the browser Application security Helios variants and related systems Mixnet-based variants Variants aiming at countering ballot-stuffing Variants aiming at perfectly private audit data Variants based on full threshold encryption Variant supporting vote delegation Alternate Helios frontends Audit tools

12 xii 11.6 Conclusion Prêt à Voter - the Evolution of the Species Peter Y A Ryan, Steve Schneider, and Vanessa Teague 12.1 Introduction End-to-End Verifiability Outline of Prêt à Voter The Voting Ceremony Vote Counting Advantages of Prêt à Voter Auditing the Election Auditing the Ballot Generation Authority Auditing Mixing and Decryption Auditing the Mixes Auditing the Decryption Tellers Cryptographic Components Decryption mixes Re-encryption mixnets Re-encryption mixes with cyclic shifts Re-encryption Mixes with Affine Transformations Re-encryption Mixes With Full Permutations Distributed generation of ballots The bulletin board Facilitating verification and privacy Encouraging cast-as-intended verification (Ballot auditing) Enhancing robustness using parallel verification mechanisms Verified Encrypted Paper Audit Trails Human Readable Paper Audit Trails Confirmation codes and signatures Accountability, dispute resolution and Resilience Cast-as-Intended Verification Authenticity of Receipts (included-as-cast verification) Tally verification

13 xiii 12.8 Vulnerabilities and Counter-measures Ballot Stuffing Information Leakage Retention of the Candidate List Forced/Coerced Randomisation Chain Voting Trash Attacks Clash Attacks Psychological Attacks Prêt à Voter Goes Down-Under Significance of the VEC Election Challenges of combining end-to-end verifiability with traditional Victorian paper voting Specific Design choices Computer-assisted voting Unified Scanner and EBM Handling complex ballots and printing them on demand The Web Bulletin Board vvote-specific vulnerabilities and countermeasures Practical experiences Conclusions DRE-i and Self-Enforcing E-Voting Feng Hao 13.1 Introduction Dining Cryptographers problem Description of the problem Chaum s original solution: DC-net Limitations of DC-net First attempt on a new solution Improved solution: AV-net Presentation at SPW Boardroom electronic voting

14 xiv Open Vote protocol Extension to multi-candidate election Presentation at WISSec Large-scale electronic voting From decentralized to centralized Trade-off Direct Recording Electronic with Integrity Setup Voting Tallying Publication of the DRE-i paper Trial elections Prototyping DRE-i Favourite chocolate election Favourite cheese election ERC Starting Grant on Self-Enforcing E-Voting A Verifiable Classroom Voting system Cryptography Meeting Pedagogy Conclusion STAR-Vote: A Secure, Transparent, Auditable, and Reliable Voting System Susan Bell, Josh Benaloh, Michael D. Byrne, Dana DeBeauvoir, Bryce Eakin, Gail Fisher, Philip Kortum, Neal McBurnett, Julian Montoya, Michelle Parker, Olivier Pereira, Philip B. Stark, Dan S. Wallach, and Michael Winn 14.1 Introduction Voter Flow Design Crypto Overview Triple Assurance Software and Hardware Engineering Usability Design Considerations User Interface Design Specification

15 xv Issues that still need to be addressed Audit The Cryptographic Workflow Threats Coercion Chain voting Absentee and provisional ballots Further analysis Conclusions and Future Work References Index