> Are there various types of GUID? Can them be slimmer than '{6EB22381-
> 8AB9-12D0-81B7-00ABC9231C29}' and still be secure?
>
> I would need them in a system where users enter GUIDs trought the Web
> so as they get money credited to their account. What I have to assure
> is that no type-mismatch or guessing GUIDs would give any other result
> than 'Sorry, Non-existant Key'

Well... you _never_ can be sure if someone just "guesses"...

First things first:
1) don't show them the GUID. Ever. Generated GUIDs tend to be
like one another and differ only slightly.

2) make sure to check server side and with some kind of cookie
or so that your input GUID is available for this client, so register
each GUID with each client. No GUID or a mismatch -> throw
an error.


Martijn Tonies
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