Full Disk Encryption

ps: Unused sectors in SSDs are erased when free’d and are made blank in preparation for rapid use.

This is where TRIM support helps.

There’s nothing to encrypt, and there are good reasons not to.

HDDs and related data remanence works rather differently on older HDD storage.

1. I assume it is encrypting the entire disk, including free space, due to how long it takes.
2. There are a couple of steps to setting up FileVault. Using the Terminal won’t make it go any faster but could omit something important.
3. The last time I tried, this procedure doesn’t work anymore in Mojave, regardless of whether you have a T2 chip. I used to do this all the time, which is why I made the assumption in #1. If you do a basic encryption of a relatively empty disk, it is very fast. Therefore, FileVault must do a little bit extra.

See if there is anything here: https://www.macworld.com/article/2883401/filevault-2-encrypts-your-whole-mac-and-disk-utility-can-encrypt-parts.html

Seems to depend if the Mac has a T2 chip or not...

https://apple.stackexchange.com/questions/331614/whole-disk-encryption-how-can-the-kernel-be-encrypted

1️⃣ “FileVault 2 encrypts the entire drive on your Mac, protecting your data with XTS-AES 128 encryption. And on Mac systems with an Apple T2 chip, FileVault 2 keys are created and protected by the Secure Enclave.”

2️⃣ “FileVault and Encrypted Volumes

When the user turns on FileVault, macOS uses 128-bit AES encryption to encrypt everything on the root volume (...old OS X release caveat expunged).

The system automatically decrypts files upon access if an authorized user is logged in, but the files remain encrypted on disk. This provides maximum security for a user’s files if all of the following are true:

• {list expunged}”.

3️⃣ “FileVault

Every Mac provides built-in encryption capability, called FileVault, to secure all data at rest. FileVault uses XTS-AES-128 data encryption to secure data on a Mac at rest. This can be applied to full volume protection to internal and removable storage devices. If a user enters an Apple ID and password during Setup Assistant, the assistant suggests enabling FileVault and storing the recovery key in iCloud...

A user who enables FileVault on a Mac is asked to provide valid credentials before continuing the boot process and to gain access to specialized startup modes, such as Target Disk Mode. Without...”

4️⃣ ”Encryption

Security and privacy are fundamental in the design of Apple File System. That's why Apple File System implements strong full-disk encryption, encrypting files and all sensitive metadata.

Which encryption methods are available depends on hardware and operating system support, and can vary for Mac, iPhone, iPad, Apple TV, and Apple Watch.

Apple File System supports the following encryption models for each volume in a container:

• No encryption
• Single-key encryption
• Multi-key encryption with per-file keys for file data and a separate key for sensitive metadata

Multi-key encryption ensures the integrity of user data. Even if someone were to compromise the physical security of the device and gain access to the device key, they still couldn't decrypt the user's files.

Apple File System uses AES-XTS or AES-CBC encryption modes, depending on hardware.“

………… Feel free to rummage further...

But it might be easier to provide a little more detail around what you’re up to here, as there seems to be an unstated question or two lurking...