The VOLT Project: Voting On Ledger Technology

Professor Steve Schneider

Surrey Centre for Cyber Security

University of Surrey

Newton Institute

November 6th 2019

1 University of Surrey DLT Testbed

Surrey Blockchain

Project VOLT: Voting on Ledger Technologies

Verifiable online elections for organisations - using DLT for verifiability - vote secrecy - verifiable integrity of the ballot

Corporate governance: managing voting rights - equity crowdfunding - smart contracts and DLT - management of shares and associated voting rights (which can be complex) - integrity and trust

A mix of technical and sociological questions

- Team includes Computer Scientists and Political Economists

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September 2017 – May 2020

Requirements on (e)-voting systems

Secrecy of the ballot: vote privacy, fairness

(this is not always a requirement…)

Integrity of the result

(this is always a requirement)

Coercion-resistance

Security?

Verifiability?

Auditability?

Where might e-voting be used?

Political/Statutory ballots

[Not within the scope of VOLT, though longer term…]

Shareholders

Industrial action ballots

Professional societies

Building societies

Student unions

Political organisations

Proposed benefits of electronic voting

Convenience

Accessibility for visually and mobility impaired voters

Prevent or reduce accidental invalid votes (e.g. in preferential voting)

Easier for remote and inaccessible voters

Managing complexity and dynamics of elections (e.g. voting rights)

Reduces costs (perhaps…)

Increases turnout (perhaps…)

It’s the 21st Century! Who uses pencils these days?

We do everything else online (banking, dating…)

Electronic voting – what’s the problem?

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Electronic voting – what’s the problem?

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Trust in the integrity of the election is critical

How do we know the result is correct?

How can we persuade others that the result is correct?

Electronic voting – what’s the problem? Cyber security

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Malware or bugs on voter devices or the election servers might tamper with votes

Electronic voting – what’s the problem? Cyber Security

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Adversaries or insiders interfering with votes in transit or on the server

Attacks at scale easier than for physical paper-based systems

Possibility of powerful and well-resourced hostile actors

“We bank online, so why not vote online?”

If we did online banking like we do online voting:

– No receipts or records of transactions

– Transaction secret from bank, but bank still needs to manage accounts

– No bank statements

– Hard to detect, and no way of challenging mistakes (or fraud)

– You would pay the cost of any fraud on your account

– No way to change your bank if you don’t trust it (honesty or competence)

Converse: we don’t vote online so why bank online?

– Trust mechanisms; verifiability; auditability; liabilities on the bank for when things go wrong.

– Financial institutions lose money but accept it as the cost of doing business – what’s the equivalent for voting systems?

Verifiability

End to end verifiability

– Individual verifiability – the voter confirms their vote is correctly in the system

• The voter can check the record and see that their vote is correctly recorded

– Universal verifiability – the processing and tally of the votes can be independently checked

• The votes that have been recorded are correctly counted

– Needs an independent trusted tamper-proof election record – DLT

Individual verifiability Universal

verifiability

VOLT project objectives

Using DLT to put end-to-end verifiability into practice

A trusted foundation for evidence to underpin election integrity

Management of voting rights and shareholding rights more generally

New voting systems and corporate governance possibilities

Understand positives and negatives in state of the art online/blockchain voting

Working with Electoral Reform Services Ltd to include verifiability in online voting systems

Initial prototype system April 2019 based on the Selene design - now trailled in two pilot votes and two real elections

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Voter experience (for the “Verify My Vote” VMV project demonstrator)

1. Voter receives login credentials, and also a commitment

2. Voter logs into the ballot system and votes in the normal way

3. After polling has closed, voter receives information to open the commitment to check their vote

4. On opening the commitment, the voter can confirm correctness of the vote that the system has recorded for them

Verifiability

The system uses cryptographic mechanisms to provide the end-to-end verifiability while preserving ballot secrecy

All verifiability evidence is posted on the DLT. This means that it can be independently checked

The design of the system rests on cryptographic commitments

Current status of VOLT project

2018: Design of VMV, for adding to ERS system April 2019: User testing of VMV, with ERS May – November 2019: Voter trials (in real ballots) and voter feedback

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How it looks in VMV: commitments on the DLT (https://vmv.surrey.ac.uk)

17 Encrypted

Tracker Commitment Credentials

Checking the vote in VMV

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Complete list of votes on the DLT (result can also be checked)

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The Distributed Ledger is a crucial component in VMV (The voting literature calls this a Web Bulletin Board)

DLT solves a real problem in verifiable voting: how to make trusted commitments and how to publish verifiability evidence DLT holds verifiability evidence for independent checking DLT enables commitments ahead of the election. Voters checking need to know commitments to trackers were unchanged from the beginning Consensus: everyone knows that they all see the same information including decrypted votes (i.e. different voters can’t be given different views)

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How does DLT help?

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• Verifiability on trusted information

DLT

Verifiability

Summary

Verifiable voting - voters can check inclusion of their vote as cast, and can challenge the election if not. Verify the evidence, not the system Proofs of correct processing of the votes Integrity of the election can therefore be verified

Some outstanding issues: Voter comprehensibility Verifiability tools (verification in practice) Management of voter credentials Future-proofing privacy (cf everlasting privacy) – on chain vs off chain information

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23 “The Polling”, William Hogarth, ~1760

Thanks!

s.schneider@surrey.ac.uk https://vmv.surrey.ac.uk

Commitments

Commitments for voters

Each voter has a secret key

The system creates a commitment to a tracker number for the voter. Think of this as the tracker number inside a box with a door that can only be opened with the secret key

The tracker number is not visible when the box is closed

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Door image courtesy of www.clipart.email

Commitments for voters

The tracker number is not visible until the box is opened

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Commitments for voters

The box and the door can be separated

The box without the door is completely sealed

Making a commitment

The box is given to the voter before the election starts (and posted on the DLT)

So the system cannot change the tracker number: it is committed to use that tracker number for that voter.

But the door will not be provided until after the election

So the voter cannot find out the tracker number at the beginning

Voting envelopes

Voting envelope

A different voting envelope is prepared for each voter

It contains the tracker number for that voter

The tracker number is not visible externally

Only the election authorities have the key to open the envelope 64

Running the election

Before the election: Election setup

The following information is committed before the election begins: • The election public key

• List of tracker numbers (e.g. 1, 12, 37, 64, 85)

• And for each voter (but anonymously):

• Voter’s cryptographic credentials

• Voting envelope

• Commitment box given to the voter (door not given out yet)

• Proofs of correctness (e.g. that the envelope matches the commitment)

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DLT Contents on Setup

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Voter Credentials Voting Envelope Commitment Vote

How it looks in VMV: contents of the DLT (https://vmv.surrey.ac.uk)

34 Voting

Envelope Commitment Credentials

Voting

When the voter casts their vote it is added to the contents of their envelope

The vote is not visible externally

Bob

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During the election

Votes are cast: included into the voting envelopes

12

64

85 37

1

Ann

Ann Ann

Bob

Bob

DLT Contents after votes have been cast

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Voter Credentials Voting Envelope Commitment Vote

1

1

1

1

1

After the election: results published with trackers

The envelopes are shuffled, opened with the election key, and the votes and tracker numbers are obtained and published

Shuffling breaks the link between decrypted votes and the votes in the voting envelopes. This gives anonymity

Tracker Vote

1 Ann

12 Ann

37 Bob

64 Bob

85 Ann

After the election

Voters are sent their doors to open their commitments

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64

+

Vote checking

The voter can check that the vote they cast matches the vote against their tracker number in the published table

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Tracker Vote

1 Ann

12 Ann

37 Bob

64 Bob

85 Ann

Checking the vote in VMV

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Complete list of votes on the DLT (result can also be checked)

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