Akka Persistence Journal Backup: Adding Automatic Hash Verification

The goal is to guarantee that a restored Akka Persistence journal has not been corrupted or tampered with, without requiring a full event replay on every startup.

Currently, administrators must copy the underlying journal store while the node is stopped and rely on external tools to compute a hash of the journal files for later comparison, a process that is not integrated into Akka’s backup/restore workflow and varies by storage backend.

What is the recommended approach for storing and verifying a journal hash during backup and restore? Should Akka provide a built‑in configuration option to automatically generate and check a hash as part of the backup process? How would this feature interact with different journal implementations such as LevelDB, Cassandra, and JDBC, and with the existing snapshot verification flag?