Installing Custom Certificates on Arch Linux

23/08/2018

One day a 1337 h4xx0r at the hackerspace[1] asked me whether I could relay a message to the hackint IRC network. This had one catch, for some reason the hackint operators insist that you only connect via TLS and use their self-signed intermediate and root certificates. I did a cursory verification[2], then looked into how to do a system-wide installation of the two .crt files. To my surprise, there is no Arch Linux wiki article on the topic, so here’s a short guide.

% cp *.crt /etc/ca-certificates/trust-source/anchors
% update-ca-trust

Merely copying the files into the destination directory isn’t enough, you need to run update-ca-trust to pound them into a form OpenSSL and friends can deal with. If everything went correctly, you’ll find new symlinks in /etc/ssl/certs with the issuer’s name in them. FWIW, something similar happens on every system update thanks to Pacman’s update-ca-trust hook. Check /usr/share/libalpm/hooks/update-ca-trust.hook for details.

[1]As hard as it is to believe, I occasionally meet actual hackers there. The kind that studies exploits, knows their way around shell code and breaks into computer systems.
[2]They’re quick to point out that comparing hashes doesn’t help you in case you get MITM’d. I tried verifying the certificate’s signature with GPG, but failed as I didn’t have anything useful imported in my local trust store.