Is the exif data in a photoshop file specific to that installation?

[exifuser]

Looking at the exif data for a png file generated by photoshop, I'm wondering if it's possible to identify the file's author.

Is the adobe license key in any of those XMP* fields?

Would it be possible to say that 2 different images were produced by the same author if there is a match on one of the exif fields?

[StarGeek]

Is the adobe license key in any of those XMP* fields?

No

Would it be possible to say that 2 different images were produced by the same author if there is a match on one of the exif fields?

No.  The best you could hope for is to figure out which version of Photoshop was used to create the file, if Photoshop even was the program used.  And that would be easily removed if desired.

Run the command FAQ #3 to see all the data in a file.

[exifuser]

Thank you StarGeek.

Do you know where it's documented what photoshop puts into the following fields?
Been hunting, but can't find it anywhere.

XMP-x:XMPToolkit
XMP-xmpMM:InstanceID
XMP-xmpMM:DocumentID
XMP-xmpMM:OriginalDocumentID

It's the InstanceId that I thought might be some unique identifier, generated when the adobe suite is installed.

[StarGeek]

XMPToolkit is what library and version was used to create the XMP in that file.  For example, exiftool would set it to something like Image::ExifTool 12.25 or Image::ExifTool 10.64.  Testing it with Adobe Bridge just now shows Adobe XMP Core 5.6-c128 79.159124, 2016/03/18-14:01:55.  My very old copy of Lightroom shows Adobe XMP Core 5.5-c002 1.148022, 2012/07/15-18:06:45.

DocumentID is a string generated to uniquely identify that image.  No idea how Adobe creates it but you can take a look on the Extra tags page under the NewGUID tag to see how exiftool would create such a tag.

OriginalDocumentID is used when an image is altered and saved as a new image.  It keeps track of the original image in a complicated workflow.

I'm not exactly sure what InstanceID might be.  My first thought would be that it would identify the session of when that the program editing the files was run.  But my quick test in editing two files shows completely different strings, xmp.iid:8413e145-ab48-0a49-96ef-4041059a16f2 and xmp.iid:670b22d1-9d58-6f4e-866f-81b29d0e91f5.

As to any documentation on these, I have no idea.  There's a lot of these tags that Adobe programs put in files to help keep track of the sources and edits made on a file as part of someone's workflow.  There may be details on these tags in the XMP specs on the Adobe website, but I've never really looked.

[exifuser]

Thank you for your help StarGeek

I asked this same question on stackoverflow. I've added a link at so back to your answer here.

https://stackoverflow.com/questions/67370646/can-exif-data-be-used-to-identify-the-author-of-a-png-file-created-in-photoshop

[Phil Harvey]

I suspected this myself, and in some of my dealings with the FBI I suggested they request details about this from Adobe, but I wasn't privy to the result.

- Phil

[StarGeek]

You may get asked to expand the answer as I believe link only answers are discouraged, maybe against the rules, not that I can find the rule someplace.  See here.

[exifuser]

>You may get asked to expand the answer

Indeed I was, so I repeated parts of your answer while leaving the link back to this forum.

[exifuser]

phil> in some of my dealings with the FBI

You are having a joke at my paranoia right?
Or are you serious?

[Phil Harvey]

Serious.