<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">On 25 May 2022, at 09:16, <<a href="mailto:Tobias.Wolf@t-systems.com" class="">Tobias.Wolf@t-systems.com</a>> <<a href="mailto:Tobias.Wolf@t-systems.com" class="">Tobias.Wolf@t-systems.com</a>> wrote:<br class=""><br class=""><blockquote type="cite" class="">I’ve a server application and need to support RSA and ECC clients at the same time.<br class="">I don’t know which certificate from my local keystore I have to send to the client, btw I have a rsa and a ecc certificate in my keystore already.<br class="">I don’t know with which certificate (rsa or ecc) a client comes during handshake of a tls connection.<br class="">How can this technically work?<br class=""></blockquote><br class="">On a protocol layer - have a look at the Client Hello which the client sent to the server prior to selection:<br class=""><br class="">Have a look at ;<div class=""><br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><a href="https://tls12.ulfheim.net" class="">https://tls12.ulfheim.net</a>. / The Illustrated TLS 1.2 Connection<div class=""><br class="">To understand this. On coding level; in openssl - most of this `should’ simply work if you’ve set up OpenSSL correctly. The code behind s_server is a good start. Other good resources are</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span><a href="https://www.feistyduck.com/library/openssl-cookbook/online/" class="">https://www.feistyduck.com/library/openssl-cookbook/online/</a></div><div class=""><br class=""></div><div class=""><br class="">Dw.</div></div></body></html>