Some of my mail, and all my Debian work, is signed with the GnuPG/PGP key which you can find here.
On post-Sarge systems, you need to add this key to your APT trusted keyring to be able to use my Debian archive. You can do this manually by downloading the key and entering (as root) one of the following commands
apt-key add frodo-looijaard.pgp
apt-key add frodo-looijaard.pgp.asc
If you do not have a program apt-key, you will probably not need to execute this either.
Alternatively, you can install the package debian-frodo-looijaard-keyring. This package can also be found by adding the following to your /etc/apt/sources file:
deb http://debian.frodo.looijaard.name/public/wheezy wheezy common
and running the following commands:
apt-get install debian-frodo-looijaard-keyring
Ignore the warnings that this package is signed with an unknown key; from now on, you will not get this warning anymore for packages from debian.frodo.looijaard.name.