I created something similar to this [1] a few years ago. Before the proliferation of web crypto apis, I just used a WASM’d libsodium. It adds some page weight but whatever…
My use-case was for traveling, it seems like a good idea to have a backup photo of my passport and credit card in case I loose everything. Sure I could put it on Dropbox, but do I really want to log in to my entire Dropbox on someone else’s machine?
Ironically, it has yet to be useful. Just a fun project inspired by the realization that you can base64 just about anything in an HTML document.