[TLS] Is Ed25519/Ed448 ok for use in DTLS1.2?

Matt Caswell <matt@openssl.org> Mon, 18 November 2019 16:50 UTC

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From: Matt Caswell <matt@openssl.org>
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Date: Mon, 18 Nov 2019 16:50:03 +0000
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Subject: [TLS] Is Ed25519/Ed448 ok for use in DTLS1.2?
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RFC8422 specifies the usage of Ed25519 and Ed448 in TLSv1.2. However
there is barely any mention of DTLS. There is one reference which says this:

"IANA has assigned one value from the "TLS HashAlgorithm" registry for
Intrinsic (8) with DTLS-OK set to true (Y) and this document as
reference.  This keeps compatibility with TLS 1.3."

That's in reference to the IANA TLS HashAlgorithm registry. But for the
TLS SignatureAlgorithm registry it says this:

"IANA has assigned two values in the "TLS SignatureAlgorithm" registry
for ed25519 (7) and ed448 (8) with this document as reference.  This
keeps compatibility with TLS 1.3."

This is in the paragraph before the other one, and there is no reference
to ed25519/ed448 being "ok" for DTLS, and in fact there is no mention of
DTLS anywhere else in this RFC.

However the IANA TLS SignatureAlgorithm registry lists ed25519/ed448 as
"ok" for DTLS and cites RFC8422 as a reference:

https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-16

Is this an error in the IANA registry? Or is this an error in the RFC?
Or is there some other RFC somewhere that specifies ed25519/ed448 usage
in DTLS?

I looked to see if there were any errata for RFC8422, but nothing looked
relevant.

Thanks

Matt