Ask HN: Is there any CDN that offers “upload tokens” to put content

I'm building an app where users can upload user generated content.

CDNs have good pricing on distribution, and I'd like the clients themselves to upload directly to the CDN without sending the data to my server (and then having the server put it on the CDN).

I'd imagine something like:

- client tells "I want to upload something of size 123123 bytes" to server

- server returns "upload token" to client, that encapsulates an authorization saying: "the holder of this token can store 123123 bytes on my behalf, content expiring on x/y/z, this auth is valid until a/b/c"

- client HTTP puts/posts 123123 bytes of data to the CDN, with the upload token passed as authorization, and gets a URL back

- client gives the URL back to the server "upload done! here's the URL to it!"

Does any CDN support this paradigm? TIA