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