Recrypt
Share a file with the people you choose. Revoke that share later. The server stores the file and still cannot read it.
What it removes
Sharing a file usually means handing it to a company, then trusting that company to forget it when you change your mind. Recrypt encrypts for one person and can be turned into a copy encrypted for another, without a server decrypting it in between. The cryptography is post-quantum.
The software works. It is not what we installed at Embassy SF. That install is Lightning Mesh. The disk in a building is Edgebox, a Raspberry Pi 5 with an SSD first and mini-PCs later. Recrypt is how a file on that box is shared. A virtual machine on the box, run by Mjolnir, is the intended proxy. That part is not running yet. The library is.