Send the client certificate

The client authentication is requested by the SSL server. It can be mandatory or optional.

If the client has certificates to provide, it can do this using OnCertificateNeededEx event. There are several ways to provide the certificate:

1. If you have a certificate chain, represented by the instance of ElX509CertificateChain class, set Certificate parameter of the event handler to the end-entity certificate, located in the chain. This is always 0'th certificate in the ElX509CertificateChain class. If you pass the certificate, which belongs to the chain, the OnCertificateNeededEx event will not be fired for the second time during the same handshake.
2. Pass the certificates one by one. The OnCertificateNeededEx event is fired again and again, letting you pass more certificates. Pass null/Nothing/nil in Certificate parameter of the event handler to stop the event from firing more during the same handshake.
3. Store the certificate(s) that you want to use for client-side authentication in the an instance of ElMemoryCertStorage class and assign this instance to ClientCertStorage property of the SSL client class.