Which method encrypts the entire database and all backups?

Transparent Data Encryption (TDE) is the method that encrypts the entire database and all backups. It works at the database level, providing a way to encrypt data while it is stored on disk, without requiring changes to the applications that access the database. This approach protects sensitive data by ensuring that the data files are encrypted, which secures the database against unauthorized access to the underlying file system where the data is stored.

TDE automatically manages encryption keys and provides a seamless way for database administrators to secure their data while minimizing the performance impact. It also ensures that all data being backed up is encrypted, thus extending its protection to backup files, which are often a critical component of data security strategies.

In contrast, other methods like column-level encryption focus on specific fields or columns within a database and do not encrypt the entire database. Application-level encryption may involve encrypting the data within the applications themselves rather than at the database level, making it less comprehensive than TDE. BitLocker, on the other hand, is a disk encryption feature primarily used to encrypt entire drives or volumes rather than specifically targeting databases and their backup processes.