iTunes Library – Which Songs Are DRM Protected?

This is actually insanely simple:

Open iTunes and go into your music library. Click on a song to ensure focus is inside the song list, press ⌘a to select all your songs, then press ⌘c to copy them.

Open the text editor of your choice, anything should do, then ⌘v paste your songs!

Ét Voíla, all your songs listed in plain text.

iTunes removed DRM from it's music catalog in 2009, so I'm wondering if your question is about iTunes at all? If not, you might be better off specifying what DRM scheme you have a question about.

That said, iTunes used FairPlay for DRM before, and as explained here, it does generate a unique key for every user. So, it will indeed be different for every customer. The same should be true for all DRM schemes, since if the customer could not be identified from the data inside the DRM scheme, it would defeat the purpose of DRM to start with.

It is also worth noting that while DRM was removed from iTunes, current downloads still contain your Apple ID in the downloaded file. However, tool exists to remove this meta-data from the media.