Re: [CFRG] ORPF patent and prior art

My understanding is the patent you refer to is specific to some
applications in the context of key management for cloud storage systems. In
no way it covers the concept or specific implementations of OPRFs. There is
prior art on OPRF going back to Chaum's work in the early 80s, work by Naor
et all in the 90s, Ford and Kaliski in 2000, Freedman et al in 2006 (the
first to formally define OPRFs), and a lot of work since then and prior to
the filing of that patent.

Hugo

On Mon, Nov 23, 2020 at 10:53 PM Fraser Tweedale <ftweedal@redhat.com>
wrote:

> Hello,
>
> While researching ORPFs I came upon a recently granted patent that
> appears to cover the main ORPF protocol defined in
> https://datatracker.ietf.org/doc/draft-irtf-cfrg-voprf/:
>
>     US Patent 10841080: Oblivious pseudorandom function in a key
>     management system - https://patents.justia.com/patent/10841080
>
> There is substantial prior art, including a scheme due to Nathaniel
> McCallum and Bob Relyea (2015)
> <http://marc.info/?l=cryptography&m=144192341714831&w=2> and its use
> in the "Tang" system for automating decryption of disks or other
> secrets (https://github.com/latchset/tang)  And possibly elsewhere.
>
> Regards,
> Fraser
>
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