A unified interface to services based around PGP would be easier to implement if a standard nomenclature for resources was available. At the moment, an ad hoc collection of machines on the internet run email-based PGP public key servers; another, overlapping, collection permit keys to be fetched by anonymous ftp and another collection have a WWW-based interface. Software is available by anonymous ftp but it is not always obvious where to look for a particular package, despite the best efforts of the authors of Frequently Asked Questions lists. Given the propensity for services to be run by graduate students without official permission from their institutions, it is not surprising that services disappear or migrate with very little warning.
In 1994, the domain pgp.net was created to allow a uniform naming scheme to be implemented. Each major component, such as public key service, or anonymous ftp access to packages, would reside on ` service .pgp.net' with that name pointing to the physical machine providing the service. With this structure, if a service is moved from one machine to another, a simple change to the DNS will record that fact --- client software need not know that any change has taken place. Examples of pgp.net addresses include ftp.pgp.net which currently points to the anonymous ftp archive at Oxford and its mirror sites, and keys.pgp.net which is a set of equal-priority MX records pointing at the current set of stable email keyservers.
It was recognized that the pgp.net resources would need to be distributed among a number of sites. (By ``distributed'' we mean simply that data may be found at more than one site; we do not say whether or not the data at one site is an identical copy of that held at another.) Accordingly, the domain has been split into regional portions by inserting ` region.' before the pgp.net. Thus, the key service intended primarily for German clients would be keys.de.pgp.net whereas British academia's ftp archive would be ftp.ac.uk.pgp.net. Note that this structure permits local customizations, such as help texts in an appropriate language, without altering the location independence of services.
At the time of writing, pgp.net is being populated. There are four sites in ftp.pgp.net --- located in Hamburg, Oxford, Paderborn and Tromsø. A mirror site in Korea is likely to come on-line shortly. The email key service has sub-domains in Germany (two servers, forming keys.de.pgp.net), Finland, The Netherlands, Norway, the UK and the USA; a Korean site is being tested. Other services implemented include www.pgp.net for a World-Wide Web interface to PGP-related resources, with sub-domains including www.de.pgp.net, www.no.pgp.net and www.ac.uk.pgp.net. The last consists of two machines, one each at UKERNA and Cambridge. The final resource presently implemented is mail.pgp.net, which provides a uniform and location-independent email address for the administrators (whoever they may be at the time) responsible for resources available within pgp.net domain. Valid addresses include postmaster@mail.pgp.net and ftpmaster@mail.pgp.net. The pgp.net domain is expected to grow substantially over the next year.