Alice and Bob use the Signal protocol to derive a key chain, sequentially using keys to encrypt/decrypt messages, and delete each key after use.

Alice        Bob

k1             k1
k2            k2
k3            k3
k4            k4
k5            k5
k6            k6
k7            k7
k8            k8
k9            k9
k10          k10
k11           k11
…….         …… nostr:note1afkmm89qpje2dzyrfclq80np7enas2l3s2g4pl5suezstfxt9thqwcg3wc