I think Miami Deluxe has VPN built in. I found the post below from Holger. I don't know were you can get a key file.
Good luck!!!
* From: Holger Kruse
* Subject: [Miami] Re: PPTP
* Date: Thu, 24 Feb 2000 15:50:44 -0800
On Thu, Feb 24, 2000 at 03:04:46PM -0600, Michael Ness wrote:
> I have recently come accross the need to use the Point to Point
> Tunneling Protocol (PPTP or VPN) for work related purposes and was
> wondering if Miami supported this protocol and/or how the use this
> protocol to log into a private network with my Amiga? Any help would be
> appreciated.
Miami Deluxe contains a client-side driver for PPTP.
--
Holger Kruse