I don’t believe there are any, but that makes sense to me.
Discussion
The goal is to decentralize storage to not rely on any particular server. Data must be portable. Thus signatures and/or hashes are required.
agreed. I think about it like this: bring your own media server file uploads, just like you can plug in any relay server for notes. files are hashed to ensure data integrity and de duplication. signatures of the content would be a nice addition.
I still think the media server spec is viable.