XML Matters: Practical XML Data Design and Manipulation for Voting Systems (Page 1 of 5 )
EVM2003 brings XML to the democratic process. In this installment, David discusses his practical experiences developing interrelated XML data formats for the EVM2003 Free Software project to develop voting machines that produce voter-verifiable paper ballots. Some design principles of format subsetting emerge. In addition, David looks at how an application-specific meaning for XML document equivalence can be programmed, and why canonicalization is insufficient. (This intermediate-level article was first published by IBM developerWorks, June 28, 2004, at http://www.ibm.com/developerWorks.)
For the last 11 months, I been involved in an organization called the Open Voting Consortium (OVC) and an associated Free Software project called EVM2003. The OVC's aim is to replace the closed-source electronic voting machines from proprietary vendors, specifically those that fail to provide a voter-verifiable paper ballot. The initial focus is elections in the U.S., but OVC systems hope to prove useful to other nations in the future. As developerWorks readers well know, software is inevitably prone to errors and to malicious tampering; it is hard to find "just trust us" to be a satisfying answer to the risk of votes being directly misrecorded onto electronic-only storage devices.
The EVM2003 project, hosted on SourceForge, is a worldwide community effort to build a reference implementation of elections software that meets a set of specifications emerging from the OVC; that organization hopes to act as a kind of standards body for elections systems. EVM2003 is programmed in Python -- with various supporting libraries -- and uses XML for almost all of its data storage/configuration requirements.
The OVC's specifications are quite detailed, and many of those details are still evolving. Issues like the security analysis and full threat model are outside the scope of this article, but are being considered carefully by many of the world’s leaders in computer security and elections technology (with yours truly contributing to this aspect). But it is worth quickly outlining the envisioned system before delving into the XML formats and source code that might support it. The code and formats I present in this installment are preliminary attempts at both; while the details are likely to change, I hope that much of the design will carry forward to voting systems that are eventually used by U.S. voters, or by those in other nations.
Currently, the OVC has publicly demonstrated its reference design; we are in the process of working with funding agencies, such as the National Science Foundation, and state universities, as well as regulatory bodies and state or federal legislatures.
An OVC-compliant polling place would contain several types of computer stations. Voting stations would come with both a GUI/touchscreen interface and an interface that allows reading-impaired voters (such as blind people) to vote using headphones and key presses. Either type of station would print out an official ballot after a voter completes his or her selections. A sighted and literate voter would read the face of this ballot to make sure that it records her intended votes; a reading-impaired voter might, as an alternative, take the ballot to an independent, non-networked ballot vocalization station that would read back recorded votes over headphones. Once verified, the paper ballots would be placed in an ordinary locked ballot box. At the end of the day, poll workers would reconcile the official paper ballots with the anonymous electronic records from the EVMs -- accounting for spoiled ballots, test ballots, and so on -- to provide extra checks against tampering. At higher levels -- such as county or state -- precincts would be aggregated (called "canvassing" in elections nomenclature), and various other integrity checks would be performed.
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