A few weeks ago I learned that a few of my colleagues were using PGP. I myself started using PGP around 2003, using the GnuPG implementation. However, since I didn't know many people who used it my usage slowly faded after a few years. In 2009 I shortly picked it up again by creating a new key to phase out SHA-1, but that was also of short duration. Thanks to my colleagues, I'm now starting to use GnuPG again. My key is still the same as created in 2009: 610DB834.
I noticed that both my PGP-key and my SSH-keys use the RSA-algorithm, so I started wondering whether it was possible to use my PGP-key to authenticate myself to SSH-servers. After some Googling it seemed possible, but not very straightforward. In the end I managed to get it working, thanks to the very friendly support of Werner Koch (the main developer of GnuPG). Since it is not very straightforward I will document my findings here for future reference.