[13927] in cryptography@c2.net mail archive
FYI: The size of a bit of entropy
daemon@ATHENA.MIT.EDU (Michael_Heyman@NAI.com)
Mon Aug 25 19:55:00 2003
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From: Michael_Heyman@NAI.com
Date: Fri, 22 Aug 2003 15:28:03 -0500
To: <cryptography@metzdowd.com>
I find it interesting that we actually know the size of a bit ;-)
From:
<http://www.sciam.com/article.cfm?articleID=3D000D6E85-2E76-1F0C-97AE80A8=
4
189EEDF>:
Planck area, approximately 10^(-66) square centimeter,=20
is the fundamental quantum unit of area determined by=20
the strength of gravity, the speed of light and the=20
size of quanta...it is as if the entropy were written=20
on the event horizon, with each bit (each digital 1 or=20
0) corresponding to four Planck areas.
I read this as the entire AES256 lookup-table (plaintext/ciphertext pair
and matching 256 bit key) only takes about 2400 square kilometers
(assuming I did my arithmetic correctly). The Larsen B ice shelf lost
this much area between 1998 and 2000. Dang, we could have used that.
The full article at:
<http://www.sciam.com/article.cfm?colID=3D1&articleID=3D000AF072-4891-1F0=
A-9
7AE80A84189EEDF>
has discussions on maximum information capacity in the physical world.
-Michael Heyman
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