[Ohttp] OHTTP applications I've seen

[Watson Ladd <[e-mail]>]

Back in 2015 Matthew Green, Ian Miers, and I came up with a privacy
preserving advertising system that was completely impractical to
deploy. We solved the impression reporting issue thanks to application
of Groth-Kohlweiss and some implementation tricks, but we could not
serve the creative in a privacy preserving way.

Our paper cited PIR, private information retrieval.  The PIR lower
bound comes from an elementary observation that the response has to
depend on the entire database. It's a slow process, and completely
insuitable for deployment due to information theoretic lower bounds.
Tor would have melted down under the load.

If Oblivous HTTP had been available, this would have been solved.
Request the creative through Oblivious HTTP, and there is no way for
the server, the request resource, or the proxy resource to infer
client characteristics as no one sees the request and the client IP
together. Without Oblivious HTTP there isn't a way to make these sorts
of design work. And unlike MASQUE Oblivious HTTP is easy to use from
Javascript in the browser, which is nice for prototyping and other
reasons.

In another privacy enhancing technology I've been working on, which
you'll hear about in a few weeks, Oblivious HTTP is the natural
solution to an information gathering problem in edge cases where a
server needs some more information. The information could identify a
client if connected to other requests, but if separated from that is
innocuous. Applying Oblivous HTTP would simplify the issue massively.

I hope these two examples illuminate what use cases the protocol is
for and help advance the charter discussion.

Sincerely,
Watson Ladd

-- 
Astra mortemque praestare gradatim