Originally Posted by Big T
As MQA has been touted as an non DRM type of system There is likely a key pair with a key on the device and the file itself which unlocks access to supplementary data on the media which then tells the decoder what level of MQA is used and other necessary metadata.
Correct, the notion of DRM for MQA has been abandoned, as confirmed by Hans Beekhuyzen with Bob Stuart. As I understand it, MQA files are digitally signed by each content provider to authenticate provenance, and each content provider's signature will have to be verifiable downstream.

Antipodes CX + Roon, 818v3, DSP 7200SEs, 218, DSP3200s