Subject: [CFRG] ORPF patent and prior art

From: Fraser Tweedale <[email-masked]>
Date: Tue, 24 Nov 2020 12:51:56 +1000

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

---

From: Hugo Krawczyk <[email-masked]>
Date: Tue, 24 Nov 2020 13:34:20 -0500

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 <[email-masked]>
wrote:

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