I assume your question is if Mattermost also supports E2E encryption for specific messages and if so, the answer is no at the moment. Feel free to suggest this feature at https://mattermost.com/suggestions (if it’s not there already).
Bumping this topic: a couple years ago, apparently a French security company published an End-to-End Encryption plugin for Mattermost under the Apache license. It hasn’t been updated in a while but still seems to work, and they tend to regularly accept patches. I’m running it on my instance - this generates private keys client-side (backuped mine as a secure Vaultwarden note), and looks overall pretty clean.
The plugin isn’t that well-known here it seems. It has a few limitations, the biggest I can think of is that files pasted in chats are not encrypted (iirc the Mattermost API did not allow for that when it was coded). Other than that, I’ve got no complains.
Github: GitHub - quarkslab/mattermost-plugin-e2ee: End-to-end encryption plugin for Mattermost
Details are posted on Mattermost End-to-End Encryption Plugin
Hi @MairusuPawa , welcome to the Mattermost forums and thanks for your suggestion!
The problem with this plugin (and others like it) is, that there are quite some known limitations and they usually do not keep up with the changes introduced by Mattermost, f.ex. newer Mattermost verisons also support a post history, message acknowledgements and priority, post reminders, etc. and I’m not sure if this will work with the plugin, the experience might suffer. I agree that there should be an end2end encryption directly in the server as a fully supported official feature, but as of today, there is none and I’m also not aware of a plugin that supports all post and channel features by providing end2end encryption, which is why I cannot recommend one personally.