Transaction GUIDs [Was: Writing a Sharp Zaurus PDA GnuCash Companion]

Linas Vepstas
Wed, 18 Sep 2002 01:12:42 -0500

repsonding to very old email,
now that I am getting email again...

On Fri, Aug 23, 2002 at 12:38:40PM +0100, Colin Pinkney was heard to remark:
> I was just looking at how GUIDs are generated, but couldn't quite figure =
> out. Seems to  have something to do with randomly selecting md5sums of
> files that constantly change.
> I'm know very little about pseudo-random algorithms and want to keep it
> simple so I'm hoping /proc/sys/kernel/random/uuid has enough entropy. But=
> guess in the end as long as it's a unique 128bit number (stored in hex
> format) it doesn't really matter, does it?=20

it matters a lot. md5 has been mathematically proven to generate unique
id's.  Most all naive algorithms fail to do so, in ways that seem subtle=20
to the naive developer but are well knows to crypto types and hackers.

(the linux kernel uuid algo is probably quite good.)


pub  1024D/01045933 2001-02-01 Linas Vepstas (Labas!) <>
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