Backup encryption protects database backup files by making their contents unreadable without the required decryption key or certificate. It matters because backup files can contain large amounts of sensitive information and may be copied or stolen from storage, transfer systems, or repositories.
In practice, database platforms can encrypt backups directly, and some features that encrypt databases at rest also encrypt their backups. Encryption does not prevent someone from copying a file, so defenders should restrict repository access, monitor unusual transfers, and store keys separately from backups. If keys are exposed or stored alongside the files, encryption may offer little protection; if they are well protected, possession of a backup alone may not be enough to read or restore its data.