this post was submitted on 13 Oct 2025
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End-to-End Encrypted Chat that YOU Control: Hosting XMPP (Jabber) with Prosody (roguesecurity.dev)
submitted 10 hours ago by starkzarn@infosec.pub to c/selfhosted@lemmy.world
15 comments fedilink hide all child comments
 

Take control of your data, join the tech chat. Host an XMPP server and leverage end-to-end encryption for your personal data

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[–] litchralee@sh.itjust.works 19 points 9 hours ago* (last edited 9 hours ago) (3 children)

When I see E2EE and XMPP mentioned, I think of this blog post by Soatok, outlining some very odd cryptographic choices in XMPP + OMEMO: https://soatok.blog/2024/08/04/against-xmppomemo/

I would very much like to see a richer playing field than just Signal for private messaging, but it's a tough nut to crack. For exactly which aspect that turns me away from XMPP for E2EE, I think this nails it down:

you only need check whether OMEMO is on by default (it isn’t), or whether OMEMO can be turned off even if your client supports it (it can).

When the competition is Signal, these sorts of details matter a lot.

[–] poVoq@slrpnk.net 11 points 7 hours ago (1 children)

That article is highly misleading.

A good response can be found here: https://www.moparisthebest.com/against-silos-signal/

[–] starkzarn@infosec.pub 3 points 3 hours ago

This is also a great article! Thanks for the link.

One cool point in favor of XMPP is that in a public setting (MUCs), there's community. Moparisbest is an active participant in several of the MUCs that I'm in. Very cool!

[–] possiblylinux127@lemmy.zip 5 points 8 hours ago

Simplex Chat is another option

[–] starkzarn@infosec.pub 6 points 9 hours ago (2 children)

This is great, I have not seen this post before. Thank you for sharing.

You make an excellent point here, that the burden of security and privacy is put on the user, and that means that the other party in which you're engaged in conversation with can mess it up for the both of you. It's far from perfect, absolutely. Ideally you can educate those that are willing to chat with you on XMPP and kill two birds with one stone, good E2EE, and security and privacy training for a friend. XMPP doesn't tick the same box as Signal though, certainly. I still rely heavily on Signal, but that data resides on and transits a lot of things that I don't control. There's a time and a place for concerns with both, but I wanted to share my strategy for an internal chat server that also meets some of those privacy and security wickets.

[–] ArcaneSlime@lemmy.dbzer0.com 11 points 9 hours ago* (last edited 9 hours ago) (2 children)

Tbf, can't the other party mess it up with signal too? I have a friend with a Samsung running stock samsung android, bloatware and all; how can I trust there's no google or samsung keylogger, which I'm pretty sure at least one of those companies installs? With copilot existing now, how can I be sure that, when that makes it's way to stock android, it won't capture the signal convo? The man uses windows, how can I be sure he won't surrender our chats to current copilot?

If you need nation-state level secrecy, rule #1 is don't associate with idiots who can't be bothered with at least the most basic opsec. I shouldn't talk to this motherfucker at all were that my case, or at least not digitally. Thankfully at worst we talk about me middlemanning him some weed, and even local PD dgaf.

My main issue for signal is (mostly iPhone users) download it "just for protests" (ffs) and then delete it, but don't relinquish their acct, so when I text them using signal it dies in limbo as they either deleted the app or never check it and don't allow notifs. If they had relinquished their acct at least it would fall back on SMS and I could still contact them but the way it was I was literally cut off from texting at least three friends until I relinquished my acct. Now maybe somehow with the removal of SMS maybe that is fixed, but also removing SMS took my biggest selling point to "normals," so, fuck me.

[–] starkzarn@infosec.pub 5 points 8 hours ago

Super true. I think this was best exemplified by SignalGate

[–] litchralee@sh.itjust.works 3 points 8 hours ago (2 children)

Tbf, can't the other party mess it up with signal too?

Yes, but this is where threat modeling comes into play. Grossly simplified, developing a threat model means to assess what sort of attackers you reasonably expect to make an attempt on you. For some people, their greatest concern is their conservative parents finding out that they're on birth control. For others, they might be a journalist trying to maintain confidentiality of an informant from a rogue sheriff's department in rural America. Yet others face the risk of a nation-state's intelligence service trying to find their location while in exile.

For each of these users, they have different potential attackers. And Signal is well suited for the first two, and only alright against the third. After all, if the CIA or Mossad is following someone around IRL, there are other ways to crack their communications.

What Signal specifically offers is confidentiality in transit, meaning that all ISPs, WiFi networks, CDNs, VPNs, script skiddies with Wireshark, and network admins in the path of a Signal convo cannot see the contents of those messages.

Can the messages be captured at the endpoints? Yes! Someone could be standing right behind you, taking photos of your screen. Can the size or metadata of each message reveal the type of message (eg text, photo, video)? Yes, but that's akin to feeling the shape of an envelope. Only through additional context can the contents be known (eg a parcel in the shape of a guitar case).

Signal also benefits from the network effect, because someone trying to get away from an abusive SO has plausible deniability if they download Signal on their phone ("all my friends are on Signal" or "the doctor said it's more secure than email"). Or a whistleblower can send a message to a journalist that included their Signal username in a printed newspaper. The best place to hide a tree is in a forest. We protect us.

My main issue for signal is (mostly iPhone users) download it "just for protests" (ffs) and then delete it, but don't relinquish their acct, so when I text them using signal it dies in limbo as they either deleted the app or never check it and don't allow notifs

Alas, this is an issue with all messaging apps, if people delete the app without closing their account. I'm not sure if there's anything Signal can do about this, but the base guarantees still hold: either the message is securely delivered to their app, or it never gets seen. But the confidentiality should always be maintained.

I'm glossing over a lot of cryptographic guarantees, but for one-to-one or small-group private messaging, Signal is the best mainstream app at the moment. For secure group messaging, like organizing hundreds of people for a protest, that is still up for grabs, because even if an app was 100% secure, any one of those persons can leak the message to an attacker. More participants means more potential for leaks.

[–] ArcaneSlime@lemmy.dbzer0.com 2 points 2 hours ago

Yes, but this is where threat modeling comes into play.

Right,:

If you need nation-state level secrecy, rule #1 is don't associate with idiots who can't be bothered with at least the most basic opsec. I shouldn't talk to this motherfucker at all were that my case, or at least not digitally. Thankfully at worst we talk about me middlemanning him some weed, and even local PD dgaf.

Though btw speaking of:

Can the size or metadata

Plenty of people have been drone striked (struck?) simply because the metadata said they were talking to the wrong guy. Frankly if you need that high of a level of secrecy, you'd be better served using tails/tor, or hell even snail mail with false return addr and a book cipher. But for:

all ISPs, WiFi networks, CDNs, VPNs, script skiddies with Wireshark, and network admins in the path

Then frankly either signal or jabber+encryption (or for that matter, simplex, briar, yadda yadda) should be fine.

Signal also benefits from the network effect, because someone trying to get away from an abusive SO has plausible deniability if they download Signal on their phone ("all my friends are on Signal" or "the doctor said it's more secure than email")

But then again, it's more likely to be known as an encrypted chat which may be a problem for them, while the abusive SO might just think XMPP is some outdated IM they know what signal is, and "my friends" can use jabber just the same as signal.

Alas, this is an issue with all messaging apps, if people delete the app without closing their account

Except not. XMPP not being tied to a phone number, if my buddy Steve deletes Conversations, while I may not be able to message him on jabber I can fall back on text. However (and again maybe now this is fixed), on signal if he deletes the app, I can no longer signal message him, nor can I SMS him because they get lost in limbo as signal messages, I'd have to email or use XMPP to get him to redownload signal, delete it properly, and THEN I can SMS him again. (Maybe no longer now that "no sms," but also "no sms now but still give us your phone number" don't sit right with me.)

[–] litchralee@sh.itjust.works 2 points 8 hours ago

Concrete example of threat modeling: if someone found out I was using Signal, for any reason at all, would that cause problems for me?

If yes, then Signal is not a good option. If no, then Signal may be appropriate. Why? Because in their documentation, they explicitly state that while messages are confidential, the fact that you're using Signal cannot be hidden, and so they don't make that guarantee.

[–] mistermodal@lemmy.ml 5 points 8 hours ago

Never cared for the way this fellow tries to argue that everything is too difficult to be useful. I've gotten plenty of friends and family on XMPP and the clients that don't have encryption on by default are easy to remember. Really blowing it out of proportion.

Honestly, what do security researchers like this even know about normal people? They sit through all kinds of inconveniences to use Facebook. This is a thought experiment.

Some of these are valid criticisms, of course, a lot of XMPP stuff feels like it from the 2010s. It's still the only real option. Matrix client or server is bloated garbage, theu moved server fixes into a walled garden, its development is dependent on funding from the USA National Endowment for Democracy technology fund. Signal has similar funding issues and is very shady with its centralization, trust issues, demanding phone numbers. Sets users up to leak all kinds of stuff in notifications like Matrix.

The strange insistence that only Signal meets their requirements makes me skeptical, as does the way they have operated in Github threads. They seem like an emotional nightmare to work with.

[–] Im_old@lemmy.world 1 points 8 hours ago (1 children)

This is great as last time I looked to set up prosody there were no official container images.

I just need to figure out how to set up slidge/matrix bridge and then I can ditch my matrix server.

[–] starkzarn@infosec.pub 1 points 8 hours ago

Yeah they just redid their container image pipeline and these containers are the result!

[–] warmaster@lemmy.world 1 points 9 hours ago* (last edited 9 hours ago) (1 children) 

STUN/TURN is literally designed to bypass network boundaries. Its necessity comes from the evil of NAT and allowing RFC1918 IP addresses behind firewalls to poke holes so that direct P2P connections can be established for VOIP.

By virtue of being technology designed to step around boundaries, you should be weary of controls around this. STUN can be used to relay from the external STUN record to other servers within the same broadcast domain. We’ll add some controls here to limit this, but it would behoove you to place this server in an isolated DMZ without connectivity to other, potentially privileged, internal hosts. Never forget network segmentation.```



Would a VLAN be enough?
[–] starkzarn@infosec.pub 4 points 9 hours ago

Yes, absolutely. It all depends on implementation. I am using VLANs for L2 isolation. I have a specific DMZ VLAN that has my XMPP server and only my XMPP server on it. My network core applies ACLs that prevent any inter-VLAN traffic from there, so even if STUN/TURN pokes holes, the most that is accessible is that single VLAN, which happens to contain only the single host that I want to be accessible.

Great question.