Re: [81attendees] What is it at the bottom of restaurant receipts?

[Paul Coverdale <[e-mail]>]

Just to add a bit more to the mystery, I had exactly the same lunch on 3
days. On each of the 3 receipts the row of 12 dingbats is completely
different, not even a repeat of any character.

Google doesn't help much. I did a search for "Quebec City" and "dingbats",
but it just came back with a listing of all the members of the National
Assembly... (that's a Canadian joke, by the way).

...Paul

>-----Original Message-----
>From: [e-mail] [mailto:[e-mail]]
>On Behalf Of Worley, Dale R (Dale)
>Sent: Tuesday, August 09, 2011 1:20 PM
>To: [e-mail]
>Subject: Re: [81attendees] What is it at the bottom of restaurant
>receipts?
>
>Comparing a few receipts, I've so far discovered:
>
>There are always 12 dingbats in the row.
>
>There are never duplicates on a single receipt.  This suggests that the
>dingbats are not a direct transcription of information, but rather
>statistically random.
>
>One can easily stack 5 receipts (60 dingbats) and see no duplicates.
>This suggests (via the birthday paradox) that there are more than 60^2 =
>3600 dingbats that are commonly used.
>
>My current guess is that there are 4096 dingbats representing 12 bits
>each, and the line represents 12 * 12 = 144 bits that are either a hash
>or a digital signature of the data in the hash.  The dingbats are
>probably to be visually compared by a human with a similar display that
>is computed by a government device from the data on the receipt.
>
>Curiously, on one receipt I have, the dingbat row consists of a sequence
>of 6 dingbats repeated twice, which seems to me to be very unlikely.
>
>Dale
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