...
...
The node join is rejected during the encryption key rotation, but this limitation may be revised in the future.
When a node joins the cluster (before/after key rotation), it receives the current encryption keys for the cache groups used for writing (it "rotates" encryption key automatically).
If the encryption key is a new key, then the node sets it for writing and starts the background re-encryption process (it starts re-encryption automatically).
Therefore, a node may leave the cluster during a key change, or a node may be absent and rejoin later (it does not matter if the baseline changes or not).
...
If the node stops/fails during re-encryption, after restarting it continue re-encryption from the stored offset:
...