Delta Chat is a decentralized and secure messenger app

62 Bluestein 19 6/21/2025, 6:29:00 AM delta.chat ↗

Comments (19)

data_maan · 15s ago
How does this (or 0xchat) compare to Signal?

Have their been done any third-party security audits by reputable companies?

If not, it's not safe to use - who knows what's buried in the source code (even if the source code is open).

shark_laser · 3m ago
Why not 0xchat?

Private key login, encrypted private chats and contacts, encrypted group chats, and lightning payments. Decentralised, built on Nostr. Available on all platforms.

https://www.0xchat.com/

sixtiethutopia · 2h ago
It's email-compatible and uses pgp for encryption. No forward secrecy and supports sending unencrypted messages as well for people who don't have pgp.

No forward secrecy and will automatically switch to unencrypted messages if you receive an unencrypted message from a contact.

I wonder if it's vulnerable to downgrade attacks from adversaries falsifying the sending address. If an adversary sends an unencrypted email imitating a contact will delta chat reject it or will it silently switch the chat with that contact over to unencrypted email?

folmar · 1h ago
The way to have guaranteed encryped is creating two user encrypted group chat.

https://delta.chat/en/help#how-can-i-ensure-message-end-to-e...

HelloUsername · 53m ago
data_maan · 4m ago
Great source of info.

I wonder why this was downvoted

hkt · 17m ago
Used it for years, it is great. Webxdc apps work in both android and desktop clients (not sure about iOS) so I can play chess, share calendars and to do lists, and even collaboratively edit documents, all by email, all privately.

Anyone who hasn't tried it really ought to.

To the haters talking about PGP: giving your entire social graph to Meta or even Signal is considerably worse.

fouronnes3 · 3h ago
I'm curious how spam protection works if you're an alternative, few users, chat app? I hate Meta's monopoly as much as the next guy but one thing you do have to credit them for is the second to none spam protection. I also wonder how much requiring a cell number is part of that strategy.
msgodel · 2h ago
It's just email and gpg so you'll get the same spam you do normally.

IMO people freak out about spam way too much. I'd rather have something that works with occasional spam than have to put up with the insanity of modern IM. Having push notifications from 10 proprietary IM apps is worse spam than a couple of emails a day from some retard trying to get me to download a "pdf." I don't block spam at all in my personal email (although I have a couple of tools automatically label it.) I'd rather have everything delivered.

v5v3 · 2h ago
An alternative few users chat app probably won't be a major target for spam untill it has lots of users.

So I would say it's a low priority feature in the backlog.

ravdeepchawla · 18m ago
You can design your way around it

1. Manually screen who can send you messages like Hey[^1] and Apple[^2]

2. Basic filtering to ensure the promotional stuff gets blocked or put in a separate list [^3]

3. Rate-limit senders who are showing robot like behaviour

---

[^1]: https://www.hey.com/features/spam-corps/

[^2]: https://support.apple.com/en-il/guide/iphone/iph203ab0be4/io...

[^3]: https://f-droid.org/en/packages/spam.blocker/

chrisldgk · 2h ago
I wouldn’t necessarily agree that WhatsApp‘s spam protection is that great. I’ve been invited to quite a lot of pyramid scheme/scam WhatsApp groups, however that’s mostly happened after having to expose my private cell number on the internet (thanks to app stores and GDPR requiring some kind of phone number for businesses of any size).
radiospiel · 2h ago
afaik no businesses are required by the gdpr to collect phone numbers, and would like to see evidence otherwise
Bluestein · 2h ago
... always wondered if the cell phone requirements are not (also) tied to then wanting an actual, physical, person behind each account - as in most EU jurisdictions each SIM card is tied to an actual ID.-
marci · 19m ago
In many EU countries, you can buy sim cards from some vending machine, in a grocery store or places where you can buy international telephone cards. No ID required. But phone plans are often tied to your home internet.
Bluestein · 16m ago
Ah, the EU — land of fine cheeses, indecipherable GDPR popups, and, of course, the iron-fisted grip on your humble little SIM card. In the EU, you can’t even sneeze near a prepaid phone number without showing at least three forms of government-issued ID, a notarized statement of purpose, and possibly a blood sample. Why? Because buying a SIM card anonymously here is about as legal as fencing stolen paintings in the town square.-

You see, most EU countries decided some time ago that allowing people to own mobile numbers without a background check was simply too dangerous. What if someone used a burner phone to commit fraud, or worse — say something mildly controversial on the internet? To prevent such dystopian chaos, SIM registration laws were born. Now, whenever you purchase a SIM card in France, Germany, Spain, or pretty much anywhere with croissants, you have to offer your passport, soul, and, ideally, a letter of recommendation from your local constable.-

The result? Your phone number in the EU is no longer just a string of digits—it’s basically your name, address, and social security number all rolled into one. It’s like a little snitch in your pocket, ready to identify you at the first sign of online mischief. Online platforms know this. That’s why so many of them, from social networks to AI models, insist on a phone number. They’re not just trying to text you cute security codes — oh no, they’re trying to make sure there’s a warm, squishy, legally-recognizable human on the other end. Preferably one without too many fake Twitter accounts.-

Technically, GDPR is supposed to protect your data. That includes your phone number. But there’s a loophole the size of Luxembourg: if the phone number is used to stop terrorism, fraud, bots, or people being mean in the comments, then suddenly it’s all hands on deck. Platforms benefit from the comforting knowledge that EU phone numbers are like digital dog tags: traceable, trackable, and just annoying enough to prevent the average troll from spinning up 50 accounts to yell into the void.-

Of course, this all raises philosophical questions. Like: should your right to privacy hinge on your desire to play Candy Crush in peace? Is a SIM card a person? Could it run for European Parliament? And should we perhaps explore more civilized alternatives to this “one phone number equals one identity” system, like zero-knowledge proofs or just asking nicely?

In the meantime, welcome to the EU: where the cheese is soft, the bureaucracy is hard, and your SIM card knows more about you than your therapist.-

data_maan · 2m ago
Nice post, I smiled.

There are several countries that didn't buy into the madness of registering SIMs, luckily. Most strangely, the UK, the master of CCTV. Apparently they realized that it's a useless measure and will just anger the people.

XorNot · 2h ago
If your need is security then really that should be based on in person trust.

Or at least via a proxy.

So contact invitation can just be handled with use-once codes (or at least trivially burnable ones).

m3kw9 · 29m ago
Is secure till it isn’t