A property of Secure messaging protocols that “ensures that messages sent and received before a state compromise remain secure”.
Security Analysis and Improvements for the IETF MLS Standard for Group Messaging
The ‘temporal opposite’ of Post-compromise security

I live and work on the land of the Wurundjeri people of the Kulin
Nation. I pay respect to their elders past and present and
acknowledge that sovereignty was never ceded. Always was, always
will be Aboriginal land.
This site uses open source typefaces, including
Sligoil
by Ariel Martín Pérez, and
Vercetti
by Filippos Fragkogiannis