Re: [Cfrg] Adoption of threshold drafts by RG

Jeff Burdges <burdges@gnunet.org> Wed, 30 September 2020 14:51 UTC

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Date: Wed, 30 Sep 2020 16:51:09 +0200
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Subject: Re: [Cfrg] Adoption of threshold drafts by RG
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Phillip,

It’s quite simple and basically free to delinearize the witnesses/nonces in a Schnorr multi-signature. 

I implemented witnesses delinearization in schnorrkel’s musig way back in early January https://github.com/w3f/schnorrkel/commit/fa6c35f832 after discussing it with numerous people in Fall 2019.  We’re not actually using witnesses delinearization in production right now, but only because our wallet folks move slowly. 

It works for threshold signatures too of course, so it appears FROST adopted roughly the same trick of delinearizing the witnesses in their recent version.  If threshold confuse matters then you should consider the simpler case of musig plus witnesses delinearization first.

If you want a multi-signer Schnorr protocol then you'll need either some form of witnesses delinearization or else some fancy determinism solution like MuSig-DN.

Best,
Jeff