DRE-i with enhanced privacy

Direct Recording Electronic with Integrity and Enforced Privacy (DRE-ip) is an End-to-End (E2E) verifiable e-voting system without involving any tallying authorities, proposed by Siamak Shahandashti and Feng Hao in 2016.

[1] It improves a previous DRE-i system by using a real-time computation strategy and providing enhanced privacy.

A touch-screen based prototype of the system was trialed in the Gateshead Civic Centre polling station on 2 May 2019 during the 2019 United Kingdom local elections with positive voter feedback.

[2] A proposal that includes DRE-ip as a solution for large-scale elections was ranked 3rd place in the 2016 Economist Cybersecurity Challenge jointly organized by The Economist and Kaspersky Lab.

[3] A browser-based prototype of the system was used in a Durga Puja online voting trial among residents of New Town, Kolkata, India, in October 2022.

The protocol consists of three stages: setup, voting and tallying.

For simplicity, the voting process is described for a single-candidate (Yes/No) election held in a polling station using a touch-screen DRE machine.

The authentication credential allows the voter to log onto a DRE machine in a private voting booth and cast a vote, but the machine does not know the voter's real identity.

A voter casts a vote on a DRE machine in two steps.

Once the voter makes a choice on the touch screen, the DRE prints the first part of the receipt, containing

[7] The interactive CDS technique can be made non-interactive by applying Fiat-Shamir heuristics.

[8] In the second step, the voter has the option to either confirm or cancel the selection.

In case of "confirm", the DRE updates the aggregated values

on the receipt, marks the ballot as "cancelled" and prompts the voter to choose again.

The canceling option allows the voter to verify if the data printed on the receipt during the first step corresponds to the correct encryption of the voter's choice, hence ensuring the vote is "cast as intended".

This follows the same approach of voter-initiated auditing as proposed by Joshua Benaloh.

The same data printed on the receipts are also published on a mirrored public election website (also known as a public bulletin board) with a digital signature to prove the data authenticity.

To ensure the vote is "recorded as cast", the voter just needs to check if the same receipt has been published on the election website.

Once the election has finished, the DRE publishes the final values

Anyone will be able to verify the tallying integrity by checking the published audit data, in particular, whether the following two equations hold.

This ensures that all votes are "tallied as recorded", which together with the earlier assurance on "cast as intended" and "recorded as cast" guarantees that the entire voting process is "end-to-end verifiable".

An "end-to-end verifiable" voting system is also said to be "software independent", a phrase coined by Ron Rivest.

A touch-screen based prototype of DRE-ip had been implemented and trialed in a polling station in Gateshead on 2 May 2019 during the 2019 United Kingdom local elections.

[2][11] During the trial, voters first voted as normal using paper ballots.

Upon exiting the polling station, they were invited to participate in a voluntary trial of using a DRE-ip e-voting system for a dummy election.

On average, it took each voter only 33 seconds to cast a vote on the DRE-ip system.

[5] As part of the trial, voters were asked to compare their voting experiences of using paper ballots and the DRE-ip e-voting system, and indicate which system they would prefer.

[5] A browser-based DRE-ip prototype was used in an online voting trial as part of the 2022 Durga Puja festival celebration, organized by the New Town Kolkata Development Authority (NKDA) together with researchers from the University of Warwick.

In this trial, residents of New Town, Kolkata, were invited to use mobile phones to vote for their favourite pujas (festival decorations) in an end-to-end verifiable manner.

The voter feedback indicated that participants generally found the E2E online voting system easy to use.