Just prototyping at the moment, but the goal is to allow users to not only share files (even big ones) but also forms, like Google forms, but encrypted and one time only (read once).
The use case I have in mind is allowing businesses to create GDPR forms (with private info, consent, etc), share unique urls with specific customers, and once the data is received by the business delete it from the server.
This could be useful to businesses that don't have a customer-facing portal, but have to deal with PII and the customer needs to consent and verify the data and what it's used for.
The data is encrypted client side (web crypto) and the password either shared in the url (in the hash fragment, also encrypted by a key stored on the server) or by other means (eg. could be the recipient's dob or id number or some other previously shared or known value).
Still trying to figure out the details, use cases, business value but the core backend is done so is the client-side crypto stuff. I managed to get chunked AES-GCM working so that it doesn't load the whole file in memory in order to encrypt it, it does that in chunks of let's say 2MB. Chrome also has chunked requests (in addition to responses) for sending the file to the server, but would probably need to come up with some other mechanism to get that working on other browsers (like send the chunks in multiple requests and append to a single file on the server, but that adds more complexity so I'm still working it out).