Re: Security markings on the ballot

From: Douglas W. Jones <jones_at_cs_dot_uiowa_dot_edu>
Date: Thu Oct 23 2003 - 16:04:17 CDT

On Thursday, October 23, 2003, at 02:28 PM, David Mertz wrote:

> I've thought a bit more about the security marking since last night. I
> still think the image (even if we play with placement), is a poor
> security measure.

I want both. Here's why:

Cryptographic signatures always end up being big numbers, barcodes or
similar things, usually printed fairly small. These can be checked
only by looking explicitly at them and reading them.

In contrast, background images or watermarks tend to jump out at you.
You'll notice a change in the image or watermark at a subconscious or
pre-intellectual level, with no need for the kinds of high-level
cognitive processing that it takes to check a 12-digit number.

So, please, put that cryptographically secure signature on the ballot,
but also, please produce a small hash code from that signature and
render that in the placement and permutation of some simple watermark
elements.

How much data can you squeeze into watermarks and have it jump out at
the viewer? Not a whole lot, but consider ballots decorated with
the state flag and the US flag as background images.

    Placement: One flag goes at the ballot top, the other at the ballot
       bottom. 1 bit of the hash of the signature determines which.

    Left-right: Each flag can be printed closer to the left or right
       side of the ballot. 2 more bits.

    Flying or draped: Each flag can be flying in the breeze (with
       wind ripples, or laid out flat and crisp. 2 more bits.

    Hanging from a vertical pole or hanging from a horizontal pole.
       2 more bits.

    Shown with or without an image of the flagpole (or perhaps, shown
       with or without a gold fringe on the flag, or both). 2 more bits.

(I don't think my proposal will offend flag-code purists, but if it
does, eliminate my first bit and always put the US flag on top.)

This gives you over 8 bits of information. If you're looking through
a stack of ballots, and all of them are displaying these same 8 bits of
information in what Dechert called a watermark but I'd rather call
a background ghost of an image, one ballot with one element of this
ghost image done wrong will very likely leap out at you.

                                Doug Jones
                                jones@cs.uiowa.edu
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Received on Fri Oct 31 23:17:04 2003

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