In order to audit a ballot, an auditor
or a voter would use the original ballot key to disclose all possible codes
for all candidates, thus revealing the
entire computational chain to prove
whether the votes were recorded and
tabulated accurately. And to verify that
a person hasn’t cheated during any
step of the process, one of the pointers can be revealed to assure that the
proper connection between the results and the anonymized encoded
ballots is maintained.
Scantegrity II is not a replacement voting system, but works with
either precinct-based or central scan
systems, a feature that Chaum says
makes it attractive to public officials.
The printing of ballots, however, requires the capability to print with
invisible ink and to print each ballot
differently.
Scantegrity II might be used in an
upcoming municipal election in Ta-koma Park, MD, a suburb of Washington, D.C., but the city council has not
yet made a final determination.
Different approaches, same Goal
While Scantegrity II appears to be
the most public election-ready system, there are several replacement
systems—most notably Prêt à Voter
(or Ready to Vote), Scratch & Vote,
and ThreeBallot—that use different
cryptography-based approaches to
achieve the same goal of end-to-end
voter verifiability.
Developed by Peter Ryan of University of Newcastle upon Tyne, Prêt à
Voter does not rely upon the voted values to be encrypted and randomized,
but uses a random candidate order
that varies from ballot to ballot. Once
a vote is cast, the side of the ballot with
end-to-end auditable
voting systems
could put the
controversy about
the merits of
electronic voting
versus paper ballots
to rest.
the list of candidates is destroyed.
The bottom of the non-discarded
side of the Prêt à Voter ballot contains
a cryptographic string with information on the discarded candidate list order. In order to decrypt the candidate
list order and determine the value of
a vote, voting officials or party representatives use a series of secret keys to
decrypt the ballots.
Prêt à Voter was successfully used
in student elections at the University
of Surrey last year, and Ryan plans to
test Prêt à Voter again in upcoming
student elections at the University of
Newcastle upon Tyne.
Scratch & Vote was developed by
Ben Adida, a research fellow with the
Center for Research on Computation
and Society at Harvard University, and
Ron Rivest, a professor of computer
science at MIT, and its format is similar to Prêt à Voter.
A Scratch & Vote ballot is perforated down the middle, and the left
side has a list of candidates’ names
and the right side has a series of cor-
news
responding check boxes. Beneath the
check boxes is a 2D-barcode. A scratch
surface is positioned below the barcode, and a perforation separates the
scratch surface from the rest of the
right half of the ballot.
If the voter wants to audit the voting process, she selects a second ballot and removes the scratch surface,
thereby voiding the ballot, which the
voter gives to a trusted party on the
premises. The trusted party scans
the barcode, reads the randomiza-tion data previously hidden under the
scratch surface, and can confirm the
ballot is correctly formed.
The voter now makes her selection
on the first ballot, discards the left
side of the ballot (which contains only
the randomized candidate order),
and gives the ballot to an election official. The election official ensures
the scratch surface is intact and de-taches the scratch surface for the purpose of discarding it. The voter enters
the ballot’s remaining checkmark (to
indicate her vote) and barcode, which
is effectively the encrypted ballot,
into a scanner.
The voter can take the remainder
of the ballot home and check on a
public Web site that her ballot was
correctly tabulated, and if it wasn’t,
she still possesses the remainder of
the ballot. In addition, the voter can
audit the tally process and the verifiable decryption conducted by the
election officials.
With Scratch & Vote, each vote is recorded as an encrypted value by using
the box that was checked to determine
which encrypted value to use. The values are tallied using homomorphic encryption, which allows for the sum of
two encrypted values to be equal to the
Artificial Intelligence
Cooperative Robot Swarms
An enterprising group of
undergraduate students at the
University of Southampton
unveiled a group of inexpensive
and identical, matchbox-sized
robots at the recent Artificial
Life XI conference. The robots
communicate with each other
via an infrared technology used
in mobile phones, and can
independently divide up tasks,
without instructions from a
central control program.
In a demonstration at the
conference, the robots, which
have green and red lights,
autonomously divided themselves
into two groups, 80% red and 20%
green. When some of the “green”
robots were removed from the
group, the remaining robots reorganized into an 80/20 split.
Swarms of robots have certain
advantages over a single, self-contained robot, according to
some roboticists. “You might
have some complex robot that
is sent to Mars, has a technical
problem, and then the mission is
basically over,” said Claus-Peter
Zauner, the leader of the swarm
robot project, in an interview
with the BBC News. “With swarm
robots, even if a percentage of
them fails, they’ll still be able to
achieve their goal.”