owner id in .sugar/default/

John Watlington wad at laptop.org
Mon May 21 10:32:33 EDT 2007

On May 18, 2007, at 1:54 PM, Holger Levsen wrote:

>> Backups are retrieved
>> from the server by virtue of a laptop's UUID -- not a  
>> cryptographic key
>> -- so the *only* instance where you have to ask a teacher to obtain a
>> backup is when your laptop was destroyed.
> Otherwise I can get it back by just asking the server and telling  
> the server
> the machines UUID?

Yes.   When a machine is first booted after a software install, it  
will contact any nearby school server for its unlocking key.
This key will be provided immediately for a school's designated  
laptops.  This process is independent of any backup restore mechanism.

The second step, taken after a child has typed in their nickname and  
selected a color, is to contact any nearby school server to register  
the nickname and look for updates.   Here again, the basic identifier  
is the UUID.

> Is(nt) the UUID the laptops hostname and thus public? So
> anybody can request anybodys backup?

No.  The UUID of a laptop is relatively hidden.  It is a large  
number, assigned in a non-contiguous fashion at manufacture, along  
with the serial number.   Both are never modified by OLPC software,  
and stored in a manner which hopefully prevents them from being  
easily changed in any other manner (if you can subvert them, you can  
subverted the entire anti-theft system.)   The UUID is not printed  
anywhere on the laptop and never displayed.  It is not used as a host  
name, and is never sent over the network in the clear.

Does using the UUID in conjuction with the serial number strengthen  
or weaken the security ?

My assumption so far has been a use of the Unix user model for files  
backed up on the server.   But we probably don't want the UUIDs  
listed in the world readable /etc/passwd file.   The nickname is non- 
unique, making it a poor choice of username.  Can we use the laptop  
serial number ?

Comments ?

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