DVD-based Clean Room for PGP and PKI

There is increasing interest in computer security these days and more and more people are using some form of PKI, whether it is signing Git tags, signing packages for a GNU/Linux distribution or just signing your emails.

There are also more home networks and small offices who require their own in-house Certificate Authority (CA) to issue TLS certificates for VPN users (e.g. StrongSWAN) or IP telephony.

Back in April, I started discussing the PGP Clean Room idea (debian-devel discussion and gnupg-users discussion), created a wiki page and started development of a script to build the clean room ISO using live-build on Debian.

Keeping the master keys completely offline and putting subkeys onto smart cards and other devices dramatically lowers the risk of mistakes and security breaches. Using a read-only DVD to operate the clean-room makes it convenient and harder to tamper with.

Trying it out in VirtualBox

It is fairly easy to clone the Git repository, run the script to create the ISO and boot it in VirtualBox to see what is inside:

At the moment, it contains a number of packages likely to be useful in a PKI clean room, including GnuPG, smartcard drivers, the lightweight pki utility from StrongSWAN and OpenSSL.

I've been trying it out with an SPR-532, one of the GnuPG-supported smartcard readers with a pin-pad and the OpenPGP card.

Ready to use today

More confident users will be able to build the ISO and use it immediately by operating all the utilities from the command line. For example, you should be able to fully configure PGP smart cards by following this blog from Simon Josefsson.

The ISO includes some useful scripts, for example, create-raid will quickly partition and RAID a set of SD cards to store your master key-pair offline.

Getting involved

To make PGP accessible to a wider user-base and more convenient for those who don't use GnuPG frequently enough to remember all the command line options, it would be interesting to create a GUI, possibly using python-newt to create a similar look-and-feel to popular text-based installer and system administration tools.

If you are keen on this project and would like to discuss it further, please come and join the new pki-clean-room mailing list and feel free to ask questions or share your thoughts about it.

One way to proceed may be to recruit an Outreachy or GSoC intern to develop the UI. Before they can get started, it would be necessary to more thoroughly document workflow requirements.