Network Protocol Version 1

The server announces itself as an IPv6 Zeroconf service of type
"_mandos._tcp".  A connecting client sends a line of text where the
first whitespace-separated field is the protocol version, which
currently is "1".  The client and server then start a TLS handshake,
with the unusual property that the server program acts as a TLS
"client" and the connecting client acts as a TLS "server".  In this
TLS handshake the client must supply an OpenPGP certificate, and the
fingerprint of this certificate is used by the server to look up (in a
list read from file at start time) which binary blob to give the
client.  No other authentication or authorization is done by the
server.  After the binary blob is sent by the server to the client,
the server closes the connection.