Delta ChatIt took a while but it's shaping up nicely :) Post-Quantum Cryptography and Reliable Deletion, better known as Forward Secrecy, are going to become available in 2026 in #deltachat. For more details, including the recent #fosdem26 talk recording:
zivi@delta will there be a possibility of unable to decrypt errors if one of the parties in a chat is offline (with their devices powered off, and such) for over 10 days and then comes back?
@zaire should be fine, see also https://www.ietf.org/archive/id/draft-autocrypt-openpgp-v2-cert-01.html#section-4.1.4
When coming online a device will first ingest pending messages, then destroy expired decryption keys.
When coming online a device will first ingest pending messages, then destroy expired decryption keys.
Autocrypt v2 OpenPGP Certificates and Transferable Secret Keys
This document describes the "Autocrypt v2 Certificate", a standard structure for an OpenPGP certificate for Internet messaging. It offers defense against store-now-decrypt-later attacks from quantum computers through post-quantum hybrid cryptography. It also enables reliable deletion ("Forward Secrecy") of received messages even when adversaries capture encrypted messages in transit and later compromise the user's message archive and secret keys. The design uses deterministically ratcheted rotating encryption subkeys with predictable expiration combined with coordinated secret key material destruction. This document also describes the structure, use, and maintenance of the OpenPGP Transferable Secret Key that corresponds with the Autocrypt v2 Certificate.