This ensures that there is no need to delete or overwrite any residual data from an encrypted volume: once the volume’s encryption key has been deleted, its previous contents are immediately unrecoverable.Ĭoverage of boot volumes by encryption varies according to the version of macOS. Securely erasing an encrypted volume, also performed when ‘erasing all content and settings’, results in the secure enclave deleting its VEK and the xART key, which renders the residual volume data inaccessible even to the secure enclave itself. On Intel Macs, they never leave the T2 chip, so are never exposed to the Mac’s Intel processor. To protect these keys, they are handled in a secure enclave in T2 and M1 chips. This means that the user can change their password without the volume having to be re-encrypted, and allows the use of special recovery keys in case the user password is lost or forgotten. When FileVault is enabled, the same VEK is used, but it’s protected by a key encryption key (KEK), and the user password is required to unwrap that KEK, so protecting the VEK which is used to perform encryption/decryption. When FileVault is disabled, data on protected volumes is still encrypted using a volume encryption key (VEK), which is protected by a hardware key and a xART key used to protect from replay attacks. The Mac Pro 2019 has replaceable internal SSDs, but following replacement new internal storage has to be initialised against that Mac’s T2 chip using Apple Configurator 2. All Macs with T2 chips, with the exception of the Mac Pro 2019, have internal storage which is soldered into place to make its removal challenging. The T2 chip acts as the storage controller for the internal SSD, so all data transferred between the Intel processor and SSD passes through an encryption stage in the T2’s hardware. To achieve that, T2 and M1 chips incorporate secure enclaves and perform encryption and decryption in hardware, rather than using CPU cycles. One of Apple’s goals in adding the T2 chip to Intel Macs, and in the design of Apple Silicon chips like the M1 series, is to make encrypted volumes the default. Most users try to avoid doing this too often as a result, so, while FileVault is secure and effective, it isn’t as widely used as it should be. Turning FileVault on and off is quite a pain, as the whole volume has to be encrypted or decrypted in the background, a process which takes many hours or even days. This imposes significant overhead of around 3%, which is more noticeable on slower storage such as hard disks, and with slower Macs. All recent Intel processors have instructions to make this easier and quicker, but all data written to an encrypted volume has to be encrypted before it’s written to disk, and all data read from it has to be decrypted before it can be used. Encryption is performed using the XTS-AES mode of AES with a 256-bit key, by the CPU. Even on old Macs, you shouldn’t assume that FileVault 1 provides any significant protection to your data.įileVault 2 was introduced in Mac OS X 10.7, and provides whole-volume encryption based on the user password. These caused problems with Time Machine backups, and have proved comparatively easy to crack. In what’s now often referred to as FileVault 1 or Legacy FileVault, only Home folders were encrypted into a sparsebundle. Since Mac OS X 10.3, when Apple released the first version of FileVault, you’ve been able to encrypt some of the contents of internal storage. FileVault is the name Apple gives its features which encrypt stored data, so that no one else can gain access to it. If your Mac is stolen or lost, the last thing you’d want someone else to have is access to all that data. Most of us keep lots of sensitive personal data stored on our Macs.
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