When a connection is secure, sometimes it's interesting to get certificate info to show user company name for example. To do this, just use OnSSLGetHandler, where you can access to some SSL properties and handle OnVeryPeerEvent, where there is a parameter called Certificate, where you can get certificate info.

procedure OnSSLGetHandler(Sender: TObject; aType:
    TwsSSLHandler; var aSSLHandler: TIdSSLIOHandlerSocketBase);
begin
  aSSLHandler := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
  TIdSSLIOHandlerSocketOpenSSL(aSSLHandler).SSLOptions.VerifyMode := [sslvrfPeer];
  TIdSSLIOHandlerSocketOpenSSL(aSSLHandler).SSLOptions.Method := sslvTLSv1;
  TIdSSLIOHandlerSocketOpenSSL(aSSLHandler).SSLOptions.Mode := sslmClient;

  TIdSSLIOHandlerSocketOpenSSL(aSSLHandler).OnVerifyPeer := OnVerifyPeerEvent;
end;


function OnVerifyPeerEvent(Certificate: TIdX509; AOk: Boolean;
    ADepth: Integer): boolean;
begin
  Result := True;

// ... read certificate properties
//  Certificate
end;