Re: Security markings on the ballot

From: David Mertz <voting-project_at_gnosis_dot_cx>
Date: Sun Oct 26 2003 - 15:10:16 CST

"Douglas W. Jones" <jones@cs.uiowa.edu> wrote:
|Right. This is why I believe that 8 bits of trivial to identify visual
|clues such as you could present with a pair of flags has real value, and
|indeed, my 8 bit hash code could be derived from a 6 or 8 digit decimal
|number.

I'm warming up more to the value of watermarks with adjustable
placement. Part of the problem to my mind is that you cannot really
count on a printer feeding entirely accurately. I find mine varies by a
couple millimeters between every page; but I'd hardly be shocked to find
an occassional ballot that printed generally correctly, but was a
centimeter off in overall positioning (including skew).

However, the RELATIVE position of various things on the page is much
more consistent. There might still be a rare partial misfeed, but
generally the page image is accurate within its margins.

As far as I can see, two images would only allow one completely reliable
dimension of variable placement--i.e. the distance between them. If we
were to incorporate THREE elements to the watermark, they would form a
triangle with precise sides and angles. The triangle might appear a
smidgeon higher or lower on the page at random, but the relative angles
would be consistent. Obviously, if the images have some sort of dot
within them, that anchors the measurement you might do with a ruler.

Anyway, I think that one could easily generate one of 256, or even 10k
different triangles, where the choice of dimensions was generated from
the keyed ballot hash.

Yours, David...

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Received on Fri Oct 31 23:17:04 2003

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