Autocrypt key rotation

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Related

Time-based ratcheting for OpenPGP (2021): Perfect forward secrecy in PGP with time-based ratcheting

Previous discussions on forward secrecy with OpenPGP:

moving-forward.pdf

There is a Double Ratchet implementation on top of OpenPGP at sequoia-pgp / openpgp-dr · GitLab with documentation at openpgp_dr - Rust

Forum topic on Off-the-Record chats:

Off-the-Record chats

Delta Chat uses OpenPGP for encryption, which does not support forward secrecy. Apart from backwards compatibility, the greatest obstacle to adding forward secrecy is multidevice support. Double Ratchet protocols (Signal protocol, XMPP OMEMO, Olm, Megolm) do not advance the ratchet on devices which are not participating in the chat, which could be a problem if one of the devices is offline for a long time. Since different devices use different keys, the protocol also depends on the server publi…