Encrypted chat service based on existing internet protocols such as email and PGP. Delta chat uses the autoencrypt protocol to ensure all messages are encrypted using the negotiation of PGP public keys.
While the service van be used with existing email accounts, the use of chatmail relay’s is encouraged, which provide easy registration of anonymous email accounts and only store (encrypted) messages temporarily, until messages are delivered to recipients.
Core of the cross platform applications is implemented in rust, the chatmail relay is a combination of dovecot, postfix, python and rust based applications
downsides
- no perfect forward secrecy yet
- no post quantum encryption yet, pgp has a draft in the works to implement ML KEM and delta chat will follow rPGP implementation of that spec
in vergelijking met nostr
Ik houd nostr’s whitenoise chat app nog steeds in de gaten, maar dat is natuurlijk wel wéér een nieuw protocol. Delta chat bouwt verder op email en PGP, focus op usability zoals signal en whatsapp. Toevoeging van offline (gezipte) webapps met e2e encrypted communicatie is ook stuk laagdrempeliger dan het uitbreiden van het nostr protocol voor een nieuw type events
fun fact
- basic user experience of the app is amazing, as the frontendcode was actually forked from the signal app repository.
press
- mentioned in Marloes de Koning’s Lekker digitaal autonoom maar wel in je eentje
links
resources
- chatmail relay example privacy policy https://nine.testrun.org/privacy.html
- introductory presentation https://youtu.be/Sku60gI7qFA?si=hIDuPIxzvbJ6Jbi0
- followup presentation https://archive.fosdem.org/2025/schedule/event/fosdem-2025-5853-delta-chat-from-e-mail-messaging-to-peer-to-peer-realtime-networking/
- https://app.media.ccc.de/v/ds25-603-usable-end-to-end-security-with-delta-chat-and-chatmail