[lkjhgfdsa57]

Seems to fit the same usecase as Freenet USK keys: https://wiki.freenetproject.org/Updateable_Subspace_Key

They allow the holder of the private key to add new data and clients who know the public USK can get notified of updates. In Freenet you can also get the old versions of the data for as long as they stay around on the network.

[niftich]

Freenet is remarkably well thought-out and solves a lot of these difficult issues like censorship resistance, deniable encryption, distributed data storage, and mutability; but it doesn't get much press these days.