Enforcing group / key_share order in TLS1.3

Hubert Kario hkario at redhat.com
Mon Jan 13 13:47:50 UTC 2020

On Friday, 10 January 2020 23:41:20 CET, Sebastian Andrzej Siewior wrote:
> Hi,
> gnutls-cli sends by default (in the supported groups extension)
> `secp256r1' first and later `x25519'. The key_share extension contains a
> key for both types. The server has both types configured both groups and
> `x25519' comes first.
> The handshake however ends up with `secp256r1'. Is there a way to tell
> openssl to prefer `x25519' over `secp256r1'?

use the server preference setting? for s_server it's the -serverpref switch

Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 115, 612 00  Brno, Czech Republic

More information about the openssl-users mailing list