From: David Carter (no email)
Date: Thu Mar 15 2007 - 09:09:04 EDT
On Thu, 15 Mar 2007, Rob Mueller wrote:
> May not be true, but:
>
>> Is it safe? - we calulated that with one billion messages you have a one
>> in 1 billion chance of a birthday collision (two random messages with
>> the same UUID).
>
> Is true.
Fair enough.
With hindsight I should probably have defined message UUIDs to be the full
MD5 hash: 128 bits isn't that much worse than 96 bits per message. What is
the CPU overhead like for calculating MD5 sums for everything on the fly?
UUIDs started out life as Mailbox UniqueID (64 bits) plus Message UID (32
bits), hence the size and rather unfortunate name. The hash algorithmn
used to generate mailbox uniqueIDs is a bit basic, which is why I switched
to generating them on the fly from master.
-- David Carter Email: University Computing Service, Phone: (01223) 334502 New Museums Site, Pembroke Street, Fax: (01223) 334679 Cambridge UK. CB2 3QH. ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
|
|
|