Volume(0).creationDateTime is same on different macOS computers

Targets macOS
1

In one of my apps, I was “cleverly” using a hash of Volume(0).CreationDateTime as a quick & dirty way to uniquely identiy different computers.

I’ve just now learned that this doesn’t work very well - for example I checked two completely different mac computers, both running 12.5, and on both of them, Volume(0) has a creation (and modification date) of 14 July 2022 at 1:48am.

I’m pretty sure this is a new behavior for macOS related to the sealed System.

Would using a different folderItem make more sense, e.g. perhaps /System/Volumes/Data ?

(This is for analytics for software installations. It doesn’t have to be high security, but it would be nice to have it working properly).

2

unique? i think this one is more unique:

Use a Shell call to this:

system_profiler SPHardwareDataType | awk '/Serial/ {print $4}'

(you can hash the result if you require to do so)

3

The following may be more useful:

system_profiler SPHardwareDataType | awk '/Hardware UUID/ {print $3}'
4

This is random, not unque but may be a soltion one can required depending on the use.

5

Then it’s badly named UUID => A universally unique identifier.

6

The “'/Hardware UUID/” is a UUID which has randomness in it.
The one i mentioned is the actual unique guaranteed serial number of the system (or a least it’s supposed to be).

7

I believe the CreationDate could be written into the chips automated or it could be a xojo bug, eighter way i’d be using a Serial number (hashed) or the MBS SystemInformation Machine Id to be as unique as possible.

8

That’s rather odd. Out of curiosity, I checked mine and it’s also 14 July 2022 at 10:48 (because of a different time zone). We can’t both have installed a new MacOS (should this be the reason why the disk had a new creation date and time) at the exact same time, can we?
What could possibly have triggered a creation date/time at that exact moment?

9

I believe it’s due to this: Signed system volume security in iOS, iPadOS, and macOS - Apple Support Essentially, the System files are on a special frozen, signed, non-modifiable filesystem. Since everyone has the exact same files, it kind of makes sense that we all have the exact same creation/modification dates as well…

3 Likes
10

One common approach is to use a network MAC address, from an Ethernet port or a wireless connection. Those are guaranteed to be unique unless the user is spoofing them, which is pretty unlikely but not impossible.

If you don’t want to do that, how about the creation date of the user’s home folder, perhaps combined with their username?

11

maybe you can use the parent of Application Support or the home folder ? (if it’s different of volume(0) perhaps volume(1)? )

my mac has these indexes:
0 = /
1 = /System/Volumes/VM
2 = /System/Volumes/Preboot
3 = /System/Volumes/Update
4 = /System/Volumes/xarts
5 = /System/Volumes/iSCPreboot
6 = /System/Volumes/Hardware
7 = /System/Volumes/Data/home

You may want to use another than drive 0?

12

For the volume’s content, this makes much sense.
For the volume itself, I’d say it’s something I didn’t expected. This means the volume’s metadata has been replaced by the one from the downloaded&installed OS, while I’d have expected a volume to keep its partitioning date&time.
Bug, feature or not even considered behaviour? :man_shrugging: