There’s a small point of terminology that’s important for getting a clear idea of the state of support for curve25519 in IETF protocols.
X25519 is the name used for key exchange (Diffie-Hellman) which has been widely supported for some years now since it was added to TLS.
Ed25519 is the name used for digital signatures (Ed is short for Edwards) which is what you need for certificates. It was a few years later to arrive in OpenSSL because TLS didn’t need it.
X25519 is the name used for key exchange (Diffie-Hellman) which has been widely supported for some years now since it was added to TLS.
Ed25519 is the name used for digital signatures (Ed is short for Edwards) which is what you need for certificates. It was a few years later to arrive in OpenSSL because TLS didn’t need it.