Support SSL Key Logging

[kaabia]

Sometimes it is necessary to do debugging with a packet capture in Wireshark. In order to decrypt TLS traffic in wireshark, it is necessary to get the session key log.

Several TLS libraries control this behavior with the SSLKEYLOGFILE environment variable. In SwitchEV/iso15118, it appears that this must be explicitly enabled in the code (not via an env var)

More info about decrypting TLS in wireshark in some slides from a presentation by a wireshark developer: https://lekensteyn.nl/files/wireshark-tls-debugging-sharkfest19us.pdf

What problem does this solve?

This will enable deeper troubleshooting when it is necessary to inspect the actual contents of the traffic. It isn't always possible to access this information using other means.