AppendKeyPair loads the given TLS key pair and appends it to tlsConfig.Certificates.

Read in a keypair where the key is password protected.

Print a password prompt on the terminal and collect a password.

Determine if a string element is in a string array.

Determine if PEM file is encrypted.

ListenAndServeTLS acts identically to http.ListenAndServeTLS, except that it expects TLS configuration.

NewTLSConfig returns an initialized TLS configuration suitable for client authentication.

Returns CA certificate.

Read a PEM file and ask for a password to decrypt it if needed.

Verify that the OU of the presented client certificate matches the list of Valid OUs.

TODO: make this testable?.