From: inssdl@dstn21.dct.ac.uk (inssdl)
Date: Mon, 25 Nov 1996 00:32:36 -0800 (PST)
To: cypherpunks@toad.com
Subject: A source of entropy?
Message-ID: <9611250834.AA11220@dstn21.dct.ac.uk>
MIME-Version: 1.0
Content-Type: text/plain


Last weekend I spent time formatting a little over 100 new floppies. When 
I was staring at the monitor between changes, I started looking at the 
volume serial number that was being thrown up for each disk.

These *appeared* to be unpredictable from the previous serial number given.

If the serial number is represented as xxxx-yyyy then sometimes yyyy 
would be one less than the previous yyyy but xxxx always seemed to be 
"random".

The disks were all brand new, no errors (from a couple of boxes of 50 and 
some odd ones), formatted at the Win95 DOS prompt with 'format a: /u' no 
volume labels and pressing 'y' to format the next disk.

Would anyone like to comment on the possible entropy from these serial 
numbers, even if it's only to say "Don't be daft, DOS derives the 
numbers like this..."

I'll probably be doing a similar number next weekend. If any interest is 
generated from this post, I could always record the serial numbers given 
to the next batch to look for correlations.

(Please don't reply with 'invest in a bulk-formatter' - I can't afford 
one right now.)

**********************************************************************
David Lucas PGDip Software Engineering @@ BEng(Hons) Civil Engineering
Postgraduate Software Engineer, University of Abertay Dundee, SCOTLAND
@ E-mail: inssdl@dstn21.dct.ac.uk @ 2+2 = 5  for large values of two @
If you're not living on the edge, then you're taking up too much space
Organisations can't have opinions, only people can and these are mine.
Dave's Doorstep is back!!!! - http://river.tay.ac.uk/~i95dl/index.html
**********************************************************************