Subject: Re: [Cfrg] RFC 6090 correctness

From: "Igoe, Kevin M." <[email-masked]>
Date: Tue, 22 Apr 2014 16:54:10 +0000

FYI, Paul Hoffmann and I are beginning work of a bis for RFC 6090.
Suggestions welcome, I'm willing to plagiarize from anyone.
However keep in mind the constraint that went into the references
used in 6090, namely that they must be old enough to clearly be 
unencumbered by the intellectual property claims made on many facets 
of EC cryptography. There are several features we would have loved to 
add, but these strayed into areas covered by existing intellectual 
property claims.

How old are Jacobi co-ordinates?  If they were invented by Jacobi himself,
we're probably on firm ground here.

> -----Original Message-----
> From: Cfrg [mailto:[email-masked]] On Behalf Of Tanja Lange
> Sent: Sunday, March 16, 2014 7:50 AM
> To: [email-masked]
> Subject: Re: [Cfrg] RFC 6090 correctness
> 
> > There are enough errata that it feels like the RFC should be updated
> to deal with them all.
> >
> If there is an update I suggest to include Jacobi coordinates. They are
> mentioned in 3.2 but not stated anywhere. This is the coordinate system
> most implementations use (they often call it projective though).
> 
> 	Tanja
> 
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---

From: David McGrew <[email-masked]>
Date: Mon, 28 Apr 2014 12:18:03 -0400

> we're probably on firm ground here.

thanks for doing this; I suggest reference [CC1986] of that RFC as a 
good place to start.

David

---

From: Tanja Lange <[email-masked]>
Date: Tue, 29 Apr 2014 02:09:54 +0200

> thanks for doing this; I suggest reference [CC1986] of that RFC as a 
They appear all over the place, e.g. in Miller's Crypto'85 paper and the
Chudnovsky-Chudnovsky-86 paper; not necessarily under the name Jacobian
coordinates. The latter paper writes (p. 413)
"4.2. (a) For the Weierstrass equation (a), the traditional choice of the
homogeneous coordinates is x = X/Z^2, y = Y/Z^3."

	Tanja