CURLOPT_SSLKEYTYPE(3) on macOS
The text 3206230551d8, as macOS 10.14.6, macOS 10.14.5, macOS 10.14.4, macOS 10.14.3, macOS 10.14.2, macOS 10.14.1, macOS 10.14, macOS 10.13.6, macOS 10.13.5, macOS 10.13.4, macOS 10.13.3, macOS 10.13.2, macOS 10.13.1, macOS 10.13, macOS 10.12.6 shipped it.
set type of the private key file