Fwd: Fwd: Fwd: PunchScan voting protocol

[Taral]

I've attached below Rick's reply to this thread. Rick Carback is a member of
the PunchScan team.

- Taral

---------- Forwarded message ----------
From: Rick Carback
Date: Dec 16, 2007 12:01 PM
Subject: Re: Fwd: Fwd: PunchScan voting protocol

 I think there are some misconceptions/assumptions in play here about the
privacy available in current systems. Punchscan was designed to provide an
unconditional levels of integrity into the voting process, not to improve
privacy over the status quo. Election officials, ultimately, are still
responsible for protecting the privacy of voters. The cryptography is meant
as a tool to be used by election officials that prevents anyone from
arbitrarily changing vote totals without getting caught. I do not think that
Punchscan is noticeably worse than current systems in terms of privacy
protection and it is still unclear to me if there is any real difference at
all.

As for specific responses:

 "Well, that's the right question.  That's the sort of question
the punchscan team should be asking themselves, and answering
in more detail that I have heretofore seen.  What threats does
punchscan claim to defend against?  What threats does it leave
to be mitigated by other (non-punchscan) means?"

 We have talked about this stuff and published it -- we're still talking
about it, see:

http://punchscan.org/papers/ibs_carback.pdf
http://punchscan.org/papers/receipts_clark.pdf
http://punchscan.org/papers/patterns_popoveniuc
http://punchscan.org/papers/pip_essex.pdf

There will be more publications in the future. Also, you might want to check
out our VoComp submission:

http://punchscan.org/vocomp.php

Unlike any other team at the competition, we were more careful with our
claims and our analysis of our system. Part of that is the reason why we
won.

 "As an example: Let's look at the plant where the ballots are
printed.  Suppose somebody attaches a tiny "spy camera" to
the frame of one of the printing presses, so as to obtain an
image of both parts of the two-part ballot (for some subset
of the ballots)."

 In a traditional system, you can put the spy cameras in the polling place
so you can watch each voter vote. That will allow you to *directly* target
and identify each voter in a location where election authorities exert *less
* control over the surrounding environment. By contrast, attacking the
printer provides you with a decryption of the ballots but not who used them
-- you still have to go out and find each voter, and the only reliable way
to do that is to catch them in the act of voting, because they could have
got rid of the receipt or swapped it (Alternatively, receipts could be given
to third parties, e.g. LWV, this is what EPIC suggests). In that sense, this
example is unrealistic. This is especially true when you include machines in
polling places that know how voters vote (in punchscan, they don't), and the
myriad of ways a voter could expose their choices to a coercer. See:

http://punchscan.org/blog/?p=6
http://punchscan.org/blog/?p=7

The comment about "partial exposure risk" looks like a misunderstanding, so
I'll ignore it....

 "Ah yes, but what is being assumed about the /properties/ of
this Election Authority?  Is the EA omnipresent and omnipotent,
like the FSM, or does it have boundaries and limitations?
For example, does it ever need to rely on employees or
subcontractors?"

 This information is in the original papers, but the EA is responsible for
generating the data, supervising the printing and packaging (which should
include tamper-evident protections), and coordinating the shipment of
ballots to polling places. Essentially, all the things a central authority
would be responsible for in a current optical scan system. It would also be
responsible for generating keys for the scanning equipment and controlling
authentication to the bulletin board, but that is all part of the bulletin
board component that could be generic to any E2E system.

I might post this to the blog, but I am sort of busy. I will let you know
when/if I do.

-R

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