FWIW, if anyone is working on the GnuTLS integration these days:
} From: Nikos Mavrogiannopoulos
} Subject: gnutls 3.6.3
}
} Hello,
} I've just released gnutls 3.6.3. This is the first release which adds
} full support of TLS1.3 (draft28), and several other features on the
} 3.6.x branch.
}
} * Version 3.6.3 (released 2018-07-16)
}
} ** libgnutls: Introduced support for draft-ietf-tls-tls13-28. It includes version
} negotiation, post handshake authentication, length hiding, multiple OCSP support,
} consistent ciphersuite support across protocols, hello retry requests, ability
} to adjust key shares via gnutls_init() flags, certificate authorities extension,
} and key usage limits. TLS1.3 draft-28 support can be enabled by default if
} the option --enable-tls13-support is given to configure script.
[...]
