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Random-Sample Voting: Real World Crypto 2016 Trial Report

The Random-Sample-Voting Project (the "Project") ran its second public trial of the Random-Sample Voting system at Real World Crypto (RWC) 2016, which was held in Stanford, California, in January 2016. The election employed the complete protocol including all 250 audit tables. Attendees were asked informally whether they would like to receive a ballot and vote. The trial was a success and has helped guide future development.

Objectives of the Real World Crypto 2016 Trial

The purpose of the RWC 2016 trial was, in addition to testing the technical system, to obtain the reaction of the attendees. It was hoped that those who voted would provide feedback not only on security of the system but on its usability as well.

Details of the Real World Crypto 2016 Trial

We proposed the following question for the RWC 2016 trial:

"Have any popular Diffie-Hellman-1024 primes been broken?"

The election configured was based on an estimation of the conference attendance, with 450 real ballots and 50 decoy ballots. To ensure with near certainty that no ballots would be duplicated, the election was defined to have a roster size of 1,000,000. The poll ran during the conference, from midnight on Wednesday January 6 through 9am on Friday January 8. Our field team distributed paper ballots to conference attendees until the close of polls. An unvoted sample ballot is available here.

Election Software

The software deployed for the trial was an improved version of the full system used at Crypto 2015, including the election authority software, the audit bulletin board (ABB), voter bulletin board (VBB), and verifiable random beacon.

In the interest of transparency, the software used in the trial is available upon request for auditing and research purposes. Please direct all requests to [software (at) rsvoting.org](mailto:software [at] rsvoting.org). The software that may be requested include:

  • Election Authority
  • Audit Bulletin Board
  • Voter Bulletin Board

Verifiable Random Bit Generation

Two different entropy sources were, for the first time, used in a single election: the New York Stock Exchange for the random selection and the NIST random beacon for the audit.

Stock Market Random Bit Generation

The bits used for the initial draw were derived from data retrieved from the Consolidated Tape Association (CTA), the reporting authority for the New York Stock Exchange. The extraction algorithm used was a Blowfish-256 CBC-MAC extractor. Only stocks with modest volume were used (at least 10,000 trades). A detailed description of the extractor is described in the Appendix.

Due to the precision reported by the CTA, prices from unofficial reporting outlets may not yield the same bits as those derived from the CTA’s reporting. In the event of a dispute, the CTA's reporting is considered correct as the reporting authority.

NIST Random Beacon Bits

The bits used for the final draw were acquired from the NIST random beacon. The United States National Institute of Standards publishes "random" values every minute online via their random beacon. They are not as "un-manipulatable" as the stock market data, but can be helpful when bits are needed at times other than market closing. (In future, it is hoped that the RSV protocol's division into batches can be done based on more than one source of randomness, one allowing immediate posting of results and the other providing more integrity later.)

Election Procedure

Random-sample elections have many steps whose execution must not overlap. The timeline below describes the events that took place to successfully run the trial. The Project managed the election through the Election Authority software.

  • Monday, January 4, 2016, 17:04 UTC - The Project published the election definition and commitments to the ABB and VBB.
  • Monday, January 4, 2016, 20:15 UTC - The New York Stock Exchange closed and the verifiable randomness for the Initial Draw was determined.
  • Tuesday, January 5, 2016, 00:30 UTC - The New York Stock Exchange published the daily summary through the Consolidated Tape Association. The random beacon committed to in the election definition derived the bits for the initial draw.
  • Tuesday, January 5, 2016, 15:16 UTC - The Project queried the random beacon for the initial draw's verifiable random bits. The Project published the initial draw to the ABB, committed the final summands to the ABB, and published the ballot authentication information to the VBB.
  • Wednesday, January 6, 2016 - The Project's field team printed the ballots.
  • Wednesday, January 6, 2016, 00:00 UTC - The VBB opened the polls and began accepting votes. The field team began distributing ballots, which included instructions for voting.
  • Friday, January 8, 2016, 18:00 UTC - The VBB closed the polls and stopped accepting votes.
  • Friday, January 8, 2016, 18:12 UTC - The Project downloaded the votes from the VBB, generated the print audit and tally information, and committed the data to the ABB in preparation for the final draw.
  • Friday, January 8, 2016, 18:30 UTC - The NIST random beacon began generating randomness to be used for the Final Draw.
  • Friday, January 8, 2016, 19:00 UTC - The NIST random beacon finished generating the random bits for the Final Draw query and the verifiable randomness for the Final Draw was determined.
  • Friday, January 8, 2016, 19:09 UTC - The Project queried the random beacon for the final draw's verifiable random bits.
  • Friday, January 8, 2016, 19:54 UTC - The Project revealed the first two batches of auditable columns on the ABB based on the final draw.
  • Friday, January 8, 2016, 19:59 UTC - The Project revealed the second two batches of auditable columns on the ABB based on the final draw.
  • Friday, January 8, 2016, 20:06 UTC - The Project revealed the final batch of auditable columns on the ABB based on the final draw.
  • Friday, January 20, 2016 (midday PST) - The Project announced the results of the election.

Election Results and Audit

A total of 21 ballots were voted, of which 20 were real and 1 was a decoy. Of the 20 real ballots, 17 believed at least one popular Diffie-Hellman prime has been broken, whereas 3 disagreed.

No duplicate ballots were generated from this configuration. The roster size was chosen to be large enough to ensure almost certainly that no duplicate ballots would be generated.

A cursory audit of the election was conducted by the Project, which entailed manual inspection that the data published to the ABB was consistent. An independent audit of the election has not yet been performed, as far as the Project is aware. The fully auditable election data derived from the VBB and ABB is available, allowing anyone to conduct a more complete, independent audit.

Caveats

This trial did not employ all of the procedural controls one would expect of a real election. In a real election, for full privacy protection, we would handle ballot printing and distribution with appropriate controls to protect the secrecy of the vote codes and the privacy of the voter.

Lessons Learned

This trial operated on a compressed schedule to allow time for announcing the results during Real World Crypto. This introduced additional administrative challenges over the Crypto 2015 trial.

  1. For the final draw, we used the NIST random beacon, which some may perceive as less than ideal with respect to verifiability. Having multiple audits using increasingly higher quality bits enables fast results with high-assurance.
  2. It was discovered that full auditability is not possible unless external parties can verify the commitments to the election definition and configuration were made prior to the initial draw. Two options have been proposed for addressing this:
    1. Use a subscriber list to announce when election definitions and commitments are published.
    2. Use a variant of the protocol that incorporates external timestamping to prove the commitments were published prior to the initial draw.
  3. System redundancy and availability was one of the lessons learned from the Crypto 2015 trial. Though we did not enact a redundant system for this trial, we developed a contingency plan to amend the election definition if system failures occurred. System redundancy remains a high priority item for the Project.

Appendix: Random Beacon's Stock Market Extractor

The extraction algorithm used was a Blowfish-256 CBC-MAC extractor. Only stocks with modest volume were used (at least 10,000 trades).

The extractor was configured with the following key and IV:

  • Key: 0x277a40d043858cd6b3b75cdccac084b2963846bdd91fb2f9243a27db0209e8d5
  • IV: 0x0

The stocks were sorted lexicographically by exchange symbol and broken into groups of 60 to generate a conservative 128-bits per group. Each group was formatted as follows (all ASCII):

YYYY-MM-DD|Symbol-1|Price-1|Symbol-2|Price-2|...

The buffer fed to the extractor was pre-pended with the length of the buffer and padded using ISO/IEC 9797-1 (i.e., a 1 bit followed by 0s). All values fed through the extractor were in Big Endian.

Appendix: NIST Random Beacon

At the time of publication, the NIST random beacon uses two independent hardware true random number generators (TRNG) made with SP 800-90 compliant components. Together, these TRNGs generate 512 bits each minute. Each record is chained, timestamped, and signed by NIST.