[vox-tech] Search Warrant Question re: GUID

[Bob Scofield]

I'm trying to understand the notion of a GUID as used in a search warrant for 
child pornography.  In fact a GUID has nothing to do with the case in which 
the defendant is charged with possessing child pornography.  The police 
officer who drafted the warrant has a section discussing various high tech 
issues that were not used in the case.  But I'm just trying to learn this 
stuff.

Below is an excerpt from the warrant.  "CPS" refers to a software program used 
by the police in child porn cases.

"CPS will also keep a record of each time an IP address is identified as being 
a download candidate for suspected child pornography on the Gnutella network.  
CPS also keeps record of each time a users GUID (Globally Unique Identifier a 
special type of identifier used in software applications to provide a unique 
reference number) is identified as being a download candidate for suspected 
child pornography on the Gnutella network."

Later in the warrant we have this:

"An investigator, using the CPS software, can also generate a historical 
report showing the dates and times that a specific GUID was logged on the 
Gnutella network, the IP address used and the SHA 1 hash values of any 
suspected child porn images or videos shared by that computer."

I've been Googling "GUID," and I see that there are various uses of GUIDs.  
But it's not crystal clear to me how it works in child porn investigations.  
Does it mean that a person's Limewire program has a unique GUID, that is 
different from another copy of the Limewire program?  Or is it that the 
person's version of Windows has a unique GUID that is different from mine?

Do Linux and open source programs have GUIDs, or is this just a Microsoft 
thing?

Thank you.

Bob