How does it work?

The SequentialAccessWriteAheadLog was introduced in NiFi 1.6.0 and provided a faster flowfile repository implementation. The encrypted version wraps that implementation with functionality to transparently encrypt and decrypt the serialized RepositoryRecord objects during file system interaction. During all writes to disk (swapping, snapshotting, journaling, and checkpointing), the flowfile containers are serialized to bytes based on a schema, and this serialized form is encrypted before writing. This allows the snapshot handler to continue interacting with the flowfile repository interface in the same way as before and continue operating on flowfile data in a random access manner, without requiring any changes to handle the data protection.

The fully qualified class org.apache.nifi.wali.EncryptedSequentialAccessWriteAheadLog is specified as the flowfile repository write-ahead log implementation in as the value of nifi.flowfile.repository.wal.implementation. In addition, new properties must be populated to allow successful initialization.