Delta Chat – Email Based PGP Encrypted Chat
85 comments
·March 5, 2025chuckadams
lopsidedgrin
> This is trying to get two drunks to stand up straight by leaning them against each other.
Thank you for painting this beautiful picture.
immibis
Presumably they have chosen and standardized a particular subset of PGP for their product, making it fully reliable and user-friendly.
usr1106
Have you used it?
hkt
They've actually cracked PGP, and email is fine, especially between self hosters and anyone using chatmail. I've been using it for years: Delta really, really works.
bo1024
Can you clarify "cracked"?
pclmulqdq
PGP has been cracked when you use it with automation in that you can steal keys slowly by relying on the meta-behavior of systems around PGP. A classic attack here is timing how long it takes for a PGP-based automated system to reject your messages.
PGP is intended for the classic "used by a human to encrypt emails manually" flow and is actually insecure if you automate around it.
pclmulqdq
Very secure, too. You get all the insecurity of automated use of PGP combined with the insecurity of using email protocols.
sras-me
In a sensible world, we would be using this, instead of whatsapp. It is amazing that even really a vast majority of, even technical people, not once stopped and looked at whatsapp, and said "Wait, e-mail can do this, we just need a pretty UI".
jasode
>It is amazing that even really a vast majority of, even technical people, not once stopped and looked at whatsapp, and said "Wait, e-mail can do this, we just need a pretty UI".
WhatsApp lets people find each other with phone numbers instead email addresses. This has a profound difference in real-world usability because it decreases friction.
Before WhatsApp, people texted each other using cell companies' SMS service.
Why did Person A (who already had an email address) send a SMS text to Person B (who also already had an email address) to chat?!? Because both people already had each others' phone number in their smartphone's address books. Recording each other's email address is less likely so it won't be used as "ids" to chat -- especially between friends & family.
To wit, my mother has already memorized my brand new phone number that I've only had for a few years but she doesn't know my email address at all even though I've sent it and re-sent it to her multiple times. To normal people, the phone numbers are more sacred than email addresses. WhatsApp was a continuation of the conveniences of SMS -- without paying 10 cents per message to the mobile phone carriers.
Friction from cognitive overhead is a big deal in technology adoption.
lxgr
> Why did Person A (who already had an email address) send a SMS text to Person B (who also already had an email address) to chat?!?
Arguably primarily because they want to chat with them and not email them. The two have vastly different UX beyond just contact discovery.
Before WhatsApp there were ICQ (also number-based!), MSN, Skype... WhatsApp's main contribution over these was indeed using phone numbers and contacts access for automated contact discovery, but I don't think it makes sense at all to characterize it as a usability improvement on email.
Another case in point: iMessage supports email addresses as identifiers too. I don't even have my phone number on there because I consider it a strictly inferior identifier (it changes every time I move countries, I lose it if payments to my operator ever lapse, unlike a TLD I have no way of owning it independently from a phone plan etc.)
jasode
>but I don't think it makes sense at all to characterize it as a usability improvement on email.
Chats in general (not WhatsApp specifically) have "better" usability than email for some people because:
+ chats skipp the extra keystrokes of email workflow such as "Compose new email" and then enter an extra "Subject:" line which makes normal people put useless things in there such as "a quick question..." and then put the real conversation in the email body. It's a bunch of extra friction for no reason when communicating informally between friends & family.
+ chat ids such as phone numbers are not given out as freely as email addresses which makes chats have less spam and clutter and more easily isolated to personal communications. Email inboxes are clogged up with a bunch of non-chat mails like shipment notifications from Amazon.
I actually prefer email comms and have told my family to send me emails instead of text chats because I'm always at my desk and can use my full keyboard to type out a reply -- but -- they ignore me and always just send text chats. Normal people have a mental model that's geared toward text chats.
E.g. I saw my aunt again 30 years after she last saw me and one of the first things she asked was "What's your phone #? I want to send you a photo when you were little." And because I received her text, I now have my aunt's phone # in my Contacts app. But I don't have her email address. She never gave it to me; and I never asked for it.
Exchanging phone #s is the natural thing to do between friends & family. On the other hand, exchanging emails is often more natural when interacting in business settings or dealing with people at arms length.
sras-me
>both people already had each others' phone number in their smartphone's address book...
Look if it is saved in the smartphone's address book, why does it matter if it is email or a phone number. I bet that people don't actually memorize even the phone numbers of people close to them these days.
>Why did Person A (who already had an email address) send a SMS text to Person B (who also already had an email address) to chat?!?
I think it is because we didn't have near universal internet access in smartphones for a long time. If Whatsapp (or something like that) was a little bit late to appear, and the tech crowd was actually a bit more smarter, things like Delta Chat had a much better chance to be in Whatsapps current place.
jasode
>Look if it is saved in the smartphone's address book, why does it matter if it is email or a phone number.
Because when people interact with each other in informal situations, it's the phone numbers that are shared. Not email addresses. Thus, email addresses are often not in the Contacts app at all.
wisienkas
I mean you could simply setup a registry of Aliases for emails to achieve the same effect?
On the same note, isn't phone numbers being more sensitive information than email nowadays, hence you might not want to share it.
A4ET8a8uTh0_v2
That ship seems to have largely sailed and the trend will be hard to reverse given how cell number has started to become all-purpose ID number tracker.
darthrupert
Email address is a *far* better identifier than a random string of numbers though. The only reason why phone number discoverability works better is because everyone keeps being in that ancient world.
drpossum
To say nothing of the fact that most people are not running their own email servers so that messaging is going to reside in places they don't own and the fact that relays get to read about everything exacerbating that problem, so you cannot really expect forward secrecy:
Does this solve all the other problems with encrypted email, which is not widely used for a reason?
Here's a discussion
https://www.latacora.com/blog/2020/02/19/stop-using-encrypte...
em-bee
Does this solve all the other problems with encrypted email
it doesn't solve all of them but a few at least. i don't believe using pgp itself is a problem. if it was deltachat could replace it with another better encryption.
metadata is a problem. that could be solved by removing messages from the email server and storing them elsewhere. (or storing them back on the server with the metadata removed). that doesn't prevent intermediate mail forwarders from keeping a copy though. i think that is the real problem. deltachat doesn't control the communication channel and can't prevent leaking. i don't know how matrix or jabber compare here. if they use intermediate servers to forward messages the problem would remain.
message content leaking is not a problem because messages won't ever be decrypted on the server.
long term secret leaking is a problem tied to the current implementation of pgp. deltachat could change that (and maybe it does?)
em-bee
messaging is going to reside in places they don't own
but that is the case with every messenger that stores messages on your behalf. telegram, whatsapp, signal... with those ALL people are not running their own servers.
whatsapp and signal store encrypted copies of the messages, and so does deltachat.
beyond that each client also stores a copy of each message locally. as does deltachat.
in difference to all others at least with deltachat i have a choice to use a different server that i trust. with whatsapp and signal i don't have that choice.
lxgr
> most people are not running their own email servers
I honestly don't care about what the people I communicate with do, as long as I have the capability to at least own my persistent identifier (i.e. my TLD).
Just having that capability exerts just the right type of pressure on large service providers to maintain a baseline quality of service, regardless of whether the majority actually makes use of it or not, just like phone number portability has done in that domain.
lxgr
No, if anything we'd be using XMPP or Matrix.
Email is the completely wrong protocol choice for instant messaging. It's just a completely different use case. You wouldn't send a letter to the fire department if your house is on fire either.
tweetle_beetle
I think the point is that it builds on existing infrastructure that almost everyone already has in their life. Whether you self-host, use a niche provider, or a mainstream provider, email provides a pretty interoperable starting point which isn't a walled garden and doesn't have to be owned by FAANG.
Are there some compromises? Of course. But creating new accounts, or using new services isn't one of them. Email-speed instant messaging is good enough for me.
And to be honest, as much as I like Matrix, it has plenty of compromise of its own - including speed/reliability when using their own servers.
immibis
Only because we choose it to be.
When you use XMPP or Matrix you know your message will be delivered instantly. When you use email you don't. But that's only because we haven't defined an extension that tells the client whether the server can deliver messages instantly. It's not really that inherent to the system. Surely you've had at least one real-time conversation by email because both of you happened to be online at the same time and nothing went wrong necessitating a message delay.
lxgr
Yes, it's theoretically possible to adapt many protocols to many use cases, but that doesn't mean it's a good idea. Email and XMPP are just geared towards very different use cases.
In particular, Email has a lot of assumptions about acceptable delivery delays, bidirectional (non-)reachability etc. baked in that would be very hard to globally undo.
wink
From the website:
> Reliable instant messaging
If it's based on e-mail, it's just not. (if we assume generally close-to-realtime delivery and not being blocked by random recipients)
foul
Email is a communication system with a lot of moving parts. You can't have reliable IM through existing MX servers but you may have it if for example SMTPs are running on your machine and you poll their data more (it's just an example, I know that with an SMTP running on your phone you'd have more problems).
hkt
See earlier on today's front page, another all in one mail server. It is much, much simpler than it was to do this. I've been self hosting email for nearly 20 years and the state of the art is considerably better now. Latency is virtually nonexistent and federation works.
giancarlostoro
I mean... WhatsApp is literally XMPP / Jabber... It's amazing that we didn't stop and said, wait, Jabber can do this, we just need a pretty UI...
Hell, Jabber can still do this. I'm not convinced of the other modern alternatives that don't have half the functional capabilities that Jabber do.
The only "downside" of Jabber is that it's XML based, but really if you think about it, that's a strength. Anyone here could probably parse the protocol effortlessly. There's also lots of fully functional clients out today, and servers that scale like nobody's business.
I'm more ashamed we don't invest more into XMPP: Google Talk, Facebook Chat and WhatsApp were built around it. These are companies with insane to scale userbases, tried and tested.
Here's a 2008 article from Facebook on using their chat with a Jabber client:
thiht
> it's XML based, but really if you think about it, that's a strength
Nope.
Another downside is the X. The protocol being extensible means that no two clients implement the same subset of extensions making it useless. I’ve been scolded in the past for using the "wrong" client, making my messages look weird for people using the "right" client. Just make a good protocol.
fsflover
> "Wait, e-mail can do this, we just need a pretty UI"
This reminds me on this nice comment thread: https://news.ycombinator.com/item?id=19217818
em-bee
i have been arguing this ever since ICQ became popular. back then i got a lot of angry reactions. i already explained it here: https://news.ycombinator.com/item?id=38029579
that generic server backend that i am describing in my linked comment is something i am using here: https://news.ycombinator.com/item?id=42159045
rapnie
The landing page may be a bit too minimal in giving overview of this cool project. I really liked the direction towards real-time P2P networking, based on Iroh [0]. See the blog post about this [1].
> After almost two years of collaboration with the wonderful Iroh team, and years of discussions with numerous experts in the decentralization space, we are happy to announce that Delta Chat 1.48 apps on all platforms contain state-of-the-art Peer-to-Peer networking support, including hole punching and forward-secret end-to-end encryption. Concretely, Delta Chat now establishes private Peer-to-Peer gossipping networks between users who start a webxdc app that uses the new joinRealtimeChannel() API.
Mulderns
There was a few talks about Delta Chat in FOSDEM'25. Seems it has come a long way since inception.
https://fosdem.org/2025/schedule/event/fosdem-2025-5853-delt...
https://fosdem.org/2025/schedule/event/fosdem-2025-5217-chat...
meitham
For those unaware, this was created by Holger Krekel, the brain behind pypy and pytest! Another great product.
Imustaskforhelp
didn't knew that!
Even though I am part of this secure messaging group chat on matrix thing and I had even created a whole tierlist of security of protocols etc. and saw delta chat & have it running and fiddled with it.
The fact that it is written by creator of pypy is wholesome!!
bluebarbet
Several years ago I tried DeltaChat and it caused an insurmountable problem: my mail provider kept locking me out of my account. Almost certainly it was because DeltaChat's suspiciously ciphertext-filled messages were triggering the abuse lockdown.
The provider was GMX and it was their fault, not DeltaChat's. But I had to call off the experiment.
josephb
> The provider was GMX and it was their fault, not DeltaChat's.
Noting that the team have put together "Chatmail" a minimal email suite designed for speed, security and convenience.
Also helps with the whole "onboarding to chat" and multiple identities not linked to existing accounts.
https://delta.chat/en/chatmail
There are multiple public servers which may be an option, instead of using an existing email account at provider X.
HelloUsername
Previous discussions:
24-jan-2021 https://news.ycombinator.com/item?id=25893626 148 comments
07-jan-2021 https://news.ycombinator.com/item?id=25674894 4 commments
27-feb-2019 https://news.ycombinator.com/item?id=19263357 11 comments
21-feb-2019 https://news.ycombinator.com/item?id=19216827 56 comments
03-feb-2017 https://news.ycombinator.com/item?id=13560279 1 comment
rahen
On the positive side, the use of P2P and IMAP makes censorship difficult, which is a strong advantage in authoritarian regimes.
However this comes with serious trade-offs. PGP lacks forward secrecy: if a key leaks, all past messages can be decrypted. Also IMAP offers no metadata privacy, anyone can see who you email and how often.
Signal and WhatsApp are likely a step ahead in terms of privacy with their double ratchet encryption (https://en.wikipedia.org/wiki/Double_Ratchet_Algorithm).
miroljub
> Signal and WhatsApp are likely a step ahead in terms of privacy
WhatsApp is closed source, so whatever they claim to can't be proven. And remember that both WhatsApp and Signal are legally required not to disclose to you whether they are spying on you or not.
miki123211
> WhatsApp is closed source, so whatever they claim to can't be proven
E2E only requires a correctly-designed client, not a correctly-designed server.
Since any binary can always be deobfuscated, deliberately putting in a backdoor in the client would be an extremely risky PR move, especially in an app as big as WhatsApp, and one surely receiving lots of attention from security researchers.
Not to mention that OpenWhisperSystems (the creators of Signal) worked with Meta on their E2E implementation, and if you don't trust them to do right, you shouldn't trust anybody.
Let's face it, people over here just don't like Meta and love to spread FUD about them.
miroljub
One trust is lost, it's hard to regain it. The fact is, the WhatsApp client is not open source, there are no reproducible builds, and only thing you have is trust in them.
If you live in an authoritarian state with a track record of spying on individual citizens, and without legal protection for the privacy of foreign citizens, it's legitimate to decide not to trust a company like Meta headquartered in the USA.
AAAAaccountAAAA
What would be the consequences, if Meta was caught doing something "funny" with e2ee? Maybe small fines, and a brief online moral panic, but I don't think people would switch to another app en masse solely because of that.
Y_Y
> Since any binary can always be deobfuscated
Are you talking about decompilation? This, is in general very difficult, and that's when the author and compiler don't want to stop you from doing it.
Go fire up jadx or ghidra or whatever you like and see if you can find the bits of code you know are there. Now try demonstrating that a bit of code isn't there.
tcfhgj
> Let's face it, people over here just don't like Meta and love to spread FUD about them.
Yep, don't like it. They already have proven to not be trustworthy by various privacy scandals in the past
ekianjo
So you trust without proof. That's nice.
bossyTeacher
I love this optimism, I really do. But to believe that any meta product can be private is to believe that Zuck actually wants that to happen. Zuck, the guy who changes company culture every 4 years or less to suit whoever is on the white house. The reality is that with a closed source product, you can't trust ANYTHING. Just because OpenWhisperSystems worked with Meta doesn't mean anything. Meta will easily silence them legally if they wanted to. And Meta can always remove or disable the implementation as they see fit.
balamatom
>Let's face it, people over here just don't like Meta and love to spread FUD about them.
It's called punching upwards.
>Since any binary can always be deobfuscated, deliberately putting in a backdoor in the client would be an extremely risky PR move, especially in an app as big as WhatsApp, and one surely receiving lots of attention from security researchers
Correct me if I'm wrong, but can't a proprietary delivery mechanism such as the App or Play stores deliver a backdoored build to an individual device, then later autoupdate it to a clean one?
rahen
edit: I was wrong, Delta Chat now has forward secrecy from v1.48: https://delta.chat/en/2024-11-20-webxdc-realtime
Furthermore metadata transparency can be made less problematic by using email aliases.
mubou
> if a key leaks, all past messages can be decrypted
Not to mention, if you revoke a key (maybe because you lost your laptop and want to be proactive about security), without any authenticated timestamping service in the mix, all past messages and signatures can no longer be trusted, regardless of the revocation date. That's why when you revoke a key on github, all your previous commits' signatures turn red.
I've never understood why no one's succeeded in doing anything about this after all these years.
darthrupert
WhatsApp obviously cannot be trusted for message privacy for the simple reason that Meta paid gazillion bucks for it. I don't understand why people need more evidence beyond that.
fdb345
the cant read your messages. thats the usp of using signal encryption
its the rest of the account and metadata that is at risk
fdb345
The most important factor with email, is that your inbox is encrypted at rest at all times... and cannot be bruteforced.
The chances of your email messages being 'man in the middled' are almost non-existent. Its a micro-percent of live investigations that does this.
The police RELY ON finding messages in either your inbox or the recipients. It doesnt matter if they are encrypted or not in reality. Of course they'd like to read them and if they are this deep into you. Its likely they still will (probably from the recipients lesser password hygiene than yours).
Almost no evidence is every 'plucked' out of the air and read. It just doesnt work that way.
However, software like Delta is better than nothing esp for normies. Its just limited in use for people who really need ways to frustrate LE.
Source: Ive been under NCA and FBI investigation before. Protonmail with the two password method stopped them every time. Memorise the 2nd password and password manager the first.
tredre3
> Ive been under NCA and FBI investigation before. Protonmail with the two password method stopped them every time. Memorise the 2nd password and password manager the first.
Unless you exclusively use proton-bridge and disabled auto-update, then proton controls all endpoints in which your passwords live.
So what is preventing the FBI from forcing Proton to serve a special UI just to you that will be used to exfiltrate your second password?
adiabatichottub
In the US you might be able to argue it amounts to "compelled speech", and is unconstitutional.
https://en.wikipedia.org/wiki/Apple%E2%80%93FBI_encryption_d...
null
7bit
You have? Why?
INTPenis
I wish I could send a one-time link to my father where we could play chess against each other by re-visiting the same link.
The e-mail part made me think of this. I have no use for an e-mail based chat but an online chess game that's easy to use without registration would be cool. He's 82 and he can't use complex sites.
lxgr
> an online chess game that's easy to use without registration would be cool
Lichess lets you play without registration, I believe (or at least one player; not sure if both sides can be anonymous).
em-bee
well then deltachat is exactly what you want because it supports webxdc apps which can run in the deltachat client. here is the chess app: https://webxdc.org/apps/#arcanecircle-chess
aslandb
would be nice if all the "no, no, this can't work! email is slow! blah blah" guys once and for all actually give it a try to the app and realize IT WORKS AND IT IS BLAZING FAST! I have been using it since years with my family and some friends without any problems, it is the best I could find after trying Matrix, XMPP, etc.
philips
My first question on this sort of thing was how well does it work with GMail. And they have an FAQ entry on it: https://providers.delta.chat/gmail
robjan
I'm pretty sure you would be quickly rate limited, especially if you participate in a few large group chats.
hobo_mark
Would love to know if someone actually runs it reliably. Especially with a Workspace email address.
meitham
The whole purpose of using a distributed IM like Delta Chat is to break free from big data leeches like Google. If you're just using Delta Chat with a centralized Gmail server as the backend, doesn’t that defeat the point?
em-bee
at one point that used to be how email worked too. for me the point of using deltachat is that it works with my existing service and that it does not depend on any particular company/service. issues with google are secondary. deltachat is still useful even with gmail.
Ah the famously friendly UX of PGP combined with the solid reliability of email. This is trying to get two drunks to stand up straight by leaning them against each other.