Is it possible to achieve forward secrecy using a one way communication channel with pre-shared secret?
I have a setup where I need to send some information across a unsafe channel between server A and server B. This communication can only go from A to B so no handshake or two way key exchange is possible.
I could simply share a key between the two servers and use symmetric encryption. But I would like to get forward secrecy if possible so that if the shared keys are compromised in the future the old communication is not compromised.
Is there a known protocol that can do this?
I guess the problem is its impossible to share random session keys like you can in say diffie-hellman and then have to rely on deterministic key generation such as TOTP which derives from the shared secret.
The data to be transmitted is less then 2 kb, all the usual stuff about authentication, replay, tampering etc. still applies.