I have this same file and am also wondering what it is for. Here are the contents of the plist:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "
http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>EnableTransactions</key>
<true/>
<key>Label</key>
<string>com.barebones.authd</string>
<key>ProgramArguments</key>
<array>
<string>/Library/PrivilegedHelperTools/com.barebones.authd</string>
</array>
<key>Sockets</key>
<dict>
<key>com.barebones.authd.socket</key>
<dict>
<key>SockPathMode</key>
<integer>438</integer>
<key>SockPathName</key>
<string>/var/tmp/com.barebones.authd.socket</string>
</dict>
</dict>
</dict>
</plist>
No idea what that SockPathMode really means though, the man page remains mysterious:
SockPathMode <integer>
This optional key specifies the mode of the socket.
Regards,
iain