curve25519 by openSSL

Question

How can i generate ec curve25519 keys using openSSL? When I run

openssl ecparam -name curve25519 -genkey -noout -out private.ec.key

I have this message

unknown curve name (curve25519)

Answer 1

Use the genpkey command:

openssl genpkey -algorithm x25519

or, for edwards25519:

openssl genpkey -algorithm ed25519

This requires a recent OpenSSL version.