X448 Key Exchange (RFC 8731)

Mark D. Baushke mdb at juniper.net
Sat Jul 4 07:34:29 AEST 2020

Hi Joseph,

To the best of my understanding, the only SSH iplementation supporting
ssh-ed448 is AsyncSSH.

OpenSSL has support for x448/ed448/curve448

LibreSSL does not yet have this support see

I would hope that offering to do the X448 implementation for LibreSSL
and patches to OpenSSH to enable either OpenSSL or LibreSSL for X448
would be well received.

I am not an OpenSSH developer, so I cannot reasssure you that OpenSSH
will ever embrace X448.

For what it is worth, FIPS 186-5 includes both Edwards25519 and
Edwards448 as approved new elliptic curves. They have also approved a
deterministic ECDSA.

NIST seems to be plugging away at Post-Quantum Cryptography (PQC)
https://csrc.nist.gov/projects/post-quantum-cryptography I suspect they
have a long way to go yet before they standardize on anything.

	Be safe, stay healthy,
	-- Mark

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