I read all through a previous thread that discussed this topic only to find "Thread Closed" at the end. ([Only registered and activated users can see links. ])

I wondered if anyone had worked out how the copy protection works?

My own thinking is this:
An un-installed SD card may have any, unique CID and it has to work in any car, so there is no copy protection at this point. Apparently, you can buy SD cards on eBay, so they have unknown CIDs and will work in any car.
Once installed in a car, it can't be used in any other, so the VIN must be used somehow.
Copying an installed card doesn't work, so the CID must be recognised at installation.
Installation requires the SD card to be write-enabled.

This means that a file containing security information must be written to the card upon installation and this file must contain the SD card CID, the vehicle VIN and probably the date so it can know something about updates.

An un-installed card could be copied onto any SD card (that it will fit into) without regard to the CID if all this is true and it would work just fine. Anyone tried this?

I don't have an un-installed card to look at, but the installed one contains a file called SECURITY.DEF and I wonder if that contains the necessary info?
I am thinking of making a copy on another SD card and just deleting the SECURITY.DEF file and see if the new card now initialises.
It seems a bit too simple!
What does anyone think? Anyone tried this?

I have an A250 in New Zealand with a nice, new map (2017), so I'm not trying to update it or copy any other maps, I'm just curious as to how it works.

I might add that I also have a 2013 AMG C63 which uses the Comand system and is updated by inserting a CD (or DVD) which installs itself into the head unit (maybe a hard drive inside?) and I have no idea how that works either!