Thunderbird has End-to-End encryption right built into it’s very core. But at a price that was annoying to me. So I decided to keep the old 68 Version together with the enigmail plugin.
Until my system recently did an update and replaced the old thunderbird with the shiny new version 78. Which comes with its very own implementation of Pretty Good Privacy – better known as PGP.
Short recap: The Enigmail plugin used a system-installed GnuPG installation (Open Source PGP-Implementation). Thunderbird on the other hand uses a library called RNP.
This has 2 drawbacks. One is, that it is a bit harder to setup my current workflow which uses a private key located on a Yubikey that I have to unlock. The setup was not as easy as it was described in some of the descriptions on the internet. But that was mainly due to my own fault. A configuration setting that did work with Enigmail but didn’t with the new Version of Thunderbird.
The main issue is that RNP currently does not support hardware tokens. But luckily there is a flag that can delegate tasks that require private keys to a third party app. So I could setup the default GnuPG to handle the signing and the decryption process. One additional advantage is that I do not need to expose private keys to Thunderbird where they need to be secured by a single master password. But that is a different story.
RNP is not GnuPG
The – for me – more annoying part is, that RNP does not use the systemwide GnuPG keychain but its own one. So for me that means that I have to maintain two keychains with public keys.
I found that a bit awkward. So I looked for a way to automatically keep the two keychains in sync. And after a bit of digging I figured, that Thunderbird keeps a GnuPG compatible public keychain right in Thunderbirds profile folder. So all I have to do is write a cron-job that exports all the public keys from one keychain and moves them over to the respective other one. Already existing keys will not be imported, missing ones will be imported though.
So this is what I now have installed as cron-job:
#!/bin/bash
THUNDERBIRD_PROFILE=~/.thunderbird/<profile-folder>
gpg --no-default-keyring \
--keyring=$THUNDERBIRD_PROFILE/pubring.gpg \
--export \
--armor | gpg --import --no
gpg --export --armor | gpg \
--no-default-keyring \
--keyring=$THUNDERBIRD_PROFILE/pubring.gpg \
--import \
--no
Optimization will follow soon by replacing the hard-coded path to the profile folder with a command that reads that from thunderbirds profile.ini file. But that is a different story.
The only drawback I have seen so far is that Thunderbird needs to be restarted after the script has actually imported one or more keys into the thunderbilrd keychain. Otherwise the new keys are not recognized.
But that is much less of a hassle and drawback than not being able to sign my outgoing email or decrypt my incoming mails.