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The Digital Poll Book System

This project is part of the Verifiable Elections software infrastructure, developed by Free & Fair. It is a Digital Poll Book System, consisting of two main components: (1) a data management application, which maintains voter lists, candidate lists, and ballot design information and provisions digital poll books before and during Election Day; and (2) a digital poll book application that runs on commodity laptop or tablet devices to enable poll workers to check in voters on Election Day.

Correctness of these software components, and security guarantees with respect to the voter data they handle, are critical aspects of this project.

Prototype Background

The DVL prototype implementations were developed as a part of the DemTech Research Project at the IT University of Copenhagen in 2011-2013 and were designed for use in Danish elections.

It is a Digital Poll Book System that is also known as a Digital Voter List System. Consequently, the code name for this prototype is DVL.

Development Process and Methodology

The DVL, including all prototypes and the current system, has been developed using the Trust-by-Design (TBD) software engineering methodology.

The TBD methodology is documented in several papers published by Joe Kiniry and his coauthors, available via

In general, a system is comprised of:

  • a top-level readme (like this one) that includes information about the system's purpose, examples of its use, fundamental concepts, system requirements, and background literature,

  • a domain analysis and a detailed architecture specifications written in the [Extended Business Object Notation (EBON)] 3,

  • formal specifications written at the source code level in one or more contract-based specification languages like [Code Contracts] 1 (for .NET systems), the [Java Modeling Language] 2 (for JVM systems), or the [Executable ANSI/ISO C Specification Language (E-ACSL)] 4,

  • protocol descriptions typically formally specified using abstract state machines (ASMs), petri nets, formally annotated collaboration diagrams, or other formal notations that have tool support for reasoning about such protocols,

  • a hand-written set of (sub)system tests and an automatically generated set of unit tests (using [PEX] 7 for .NET systems and [ JMLUnitNG] 8 for JVM ones), including reports on the completeness and quality of these validation artifacts, and

  • a set of evidence that the system fulfills its requirements, usually in the form of traceable artifacts from the requirements to other artifacts that validate that they are satisfied (e.g., test results, code reviews, formal proofs, etc.).


What follows are the mandatory and secondary requirements imposed upon the DVL. Informal verification (in the traditional software engineering sense) of these requirements is accomplished by several means, including formal verification of properties of the system's specification and implementation, as well as traceability from the requirements to artifacts that validate that they are satisfied (e.g., system tests, code review, etc.).

Mandatory Requirements

  • Must be able to generate voter cards from a given set of eligible voters
  • Must be able to authenticate a voter based on a voter card number
  • Must be able to record when a voter has been given a ballot and securely store this information for posting voting history
  • Must prevent a voter from being issued more than one ballot
  • Must be able to authenticate and register voters at multiple machines simultaneously in various venues across the jurisdiction
  • Must have an interactive user interface for authentication and registration
  • Must be able to print out the current voter list at any point of the election

Secondary Requirements


  • The user interface must be trivial to use for non-technical users (election representatives).
  • The voter should be able to register at any table at the voting venue.


  • The system will exhibit no data loss from an arbitrary failure (e.g., a typical system failure like a Windows crash) of any system in the DVL network.
  • The system will exhibit no data loss in the event of a network failure.


  • The system should be able to handle a large number of voters (approximately 30,000 voters in a single voting venue with 10 machines running the DVL).


  • The system should use proper security measures and cryptography to establish confidence that the system is secure.
  • The system should be able to filter voters in a voter list based on multiple criteria to determine eligible voters.
  • The system should be able to provide sufficient audit information to allow the detection of suspicious voters and fraud.
  • The system should be able to provide a status report on the digital voter list prior to an election and afterwards.


  • The system should be able to provide an analysis of the turnout, both nationally and for specific turnout results.
  • The system should have a public API for the media or any citizen to access (after the election).
  • The system should be able to visualize the turnout results.
  • The system should be able to print the list of eligible voters.


Several variants of the DVL were developed by around a dozen students for end-of-term projects in the ITU course "Analysis, Design, and Software Architecture with Project" under the supervision of Joe Kiniry in Q4 2011. These experiments are collected in the "prototypes" directory in the repository.

The students that built these prototypes are Claes Martinsen, Niels Martin Søholm Jensen, and Jan Aagaard Meier (P1); Emil Blædel Nygaard, Michael Oliver Urhøj Mortensen, and Rasmus Greve (P2); Jens Dahl Møllerhøj, Michael Valentin Erichsen, and Morten Hyllekilde Andersen (P3); and Christian Olsson, Kåre Sylow Pedersen, and Henrik Haugbølle (P4). Each prototype was built in under one month using an early version of the Trust-by-Design (TBD) methodology (see above).

Each prototype includes a short project overview, an architecture specification, an implementation, and a validation suite. Different prototypes focused on different aspects of the problem; e.g., some focused on networking, others on crypography, etc.

In the following year (Q1-Q2 2012), two students, Nikolaj Aaes and Nicolai Skovvart, developed an entirely new version of the DVL that they called "the Aegis Digital Voter List", based upon what was learned from the prototypes. They used a refinement of TBD for their work and spent six months developing the system. Their system is meant to be the foundation for a real, deployable, usable, fault tolerant, secure DVL.

In early 2013 (Q1-Q2 2013), Morten Hyllekilde Andersen took over the management of the project and made some technical contributions to it. The intention of his work was to focus on election law and regulations to ensure that we knew exactly what was necessary to prepare the DVL for using in binding elections.

Starting in July 2013, Joe Kiniry took over development of the project to push it to completion for use in 2013 elections.

Development Instructions

In order to develop on the prototype DVL the following software libraries, tools, and frameworks must be installed.


The Digital Voter List system—experiments in electronic poll books for Denmark.







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