FileVault prevents access to your Mac at startup without the password for an account with permission to boot the computer. Instead of loading macOS, enabling FileVault has your Mac pass control after startup to a very simple program that resembles the standard macOS login window. Entering a valid account password on this screen allows that program to access the encryption key to unlock the startup disk and proceed seamlessly (and invisibly) into your regular Mac session. Because FileVault is integrated into macOS at such a deep level, there’s only an on/off button. You don’t need to manage any of the parts.

On Macs without a T2 chip or Apple silicon processor, FileVault also performs full-disk encryption (often called FDE). But that’s automatic and cannot be turned off on T2/Apple silicon Macs.

Starting in macOS 26 Tahoe, FileVault is automatically enabled for all users in new installations and via upgrades. It can be disabled; read on to find out if you have a reason to do so. If you didn’t previously have FileVault enabled, the first time you start up in Tahoe, you will see a message that “Your Mac is [sic] Protected by FileVault.” The dialog further explains that the Passwords app has the critical Recovery Key (see where to find your FileVault Recovery Key).

Apple also got rid of a lingering potential path for crackers and government intrusion by switching from relatively insecure storage in iCloud to fully secure storage. This is welcome!

Should you ever disable FileVault?

FileVault is an additional protection for all users that prevents unwanted access to their data. However, despite my strong recommendation to enable it, it is overkill for some people that could result in them losing access to their data in specific circumstances.

What are those circumstances?

First, they would have to either be unable to remember or find their macOS account password, or the FileVault login data for accounts would have to become corrupt and reject a legitimate password.

Second, they then couldn’t find or gain access to their FileVault Recovery Key, discussed in where to find your FileVault Recovery Key.

Most people enter their macOS account password routinely and are unlikely to forget it. But it is the case that you can experience a problem that scrambles the normal startup FileVault login. If so, your FileVault Recovery Key is your only hope. If that becomes irretrievable, you’re sunk.

So before you proceed, consider if protection for your data when the computer is turned off is worth the risk of disabling FileVault.

How startup encryption works

Full-disk encryption puts a layer between the operating system and a storage drive that automatically decrypts all information coming off the drive and encrypts it as it’s written. This means all information on the drive “at rest” is fully encrypted.

Only while a Mac is active is stored information vulnerable to interception: macOS holds the encryption key in memory to allow it to encrypt and decrypt data on the fly. This allows a Mac to treat an encrypted volume as if it were effectively not encrypted at all while the volume is in use, including letting you share the volume over a network and back it up to an external drive, a networked volume, or an internet service, and use sync services like Dropbox, iCloud Drive, and OneDrive.

Whenever a Mac is shut down, a drive is an inaccessible vault, with no more information accessible than a lump of solid metal. The key material necessary to decrypt its data can’t be accessed.

The introduction of the T2 chip, and, later, Apple silicon, removed all overhead, and Apple made the decision for security reasons that FDE is always enabled on T2/Apple silicon Macs, even if FileVault is not. This also means T2/Apple silicon Macs can enable or disable FileVault in seconds, if desired.

However, without FileVault enabled, the drive is automatically decrypted on startup even before an account password is entered! That’s the piece that FileVault fills in.

With an Apple silicon Mac, the startup process without FileVault begins with operations that retrieve the security key, which is mediated by the Secure Enclave. If the SSD drive is removed from the Mac, which in modern Macs is difficult enough to be infeasible, the decryption information remains in the Secure Enclave left behind. It seems unlikely a thief or corporate or government spy would take the drive and not the whole computer, however.

Additional protections available in Apple silicon, combined with changes in macOS (starting back in Big Sur), allow that Mac to unlock the system files to boot directly into macOS without exposing any user data files.

Your data and Mac remain protected until a valid account password is entered, at which point the key protecting the data is made available for use, and startup proceeds. This may feel like enough for you. However, Apple seems to think it isn’t, and thus enables FileVault by default in Tahoe.

Encrypt external drives

You can also encrypt any mountable SSD, HDD, or disk image that is not configured as a macOS startup drive.

There are two primary ways to encrypt non-startup volumes:

• Control-click or right-click in the Finder: This is the easiest method, and will take place in the background. Control-click or right-click the volume and choose Encrypt. Enter and verify a strong password, preferably one you generated in a password-management app. Add a hint if you think it will help. Click Encrypt Disk. This converts the drives in the Finder without losing any data. (Disk Utility, by contrast, can change a volume’s format type to the encrypted flavor, but it always erases the volume—and warns you before you proceed.)
• Disk Utility for disk images: Disk Utility can also create encrypted disk images, though it uses a different method. Choose New Image > Blank Image, then choose 256-bit AES from the Encryption menu. You’re prompted to enter and verify a password, but not store a reminder tip. Set other parameters as needed and click Save to create the image.

In the future, you have to enter the password for a volume to mount an encrypted volume or disk image in the Finder or to access it via Disk Utility. When mounted, the drive appears as fully decrypted to the Finder, just like a startup volume with FileVault, and can be shared, synced, and backed up.

Apple notes carefully that passwords created for any encrypted drive other than the startup volume aren’t managed in the Secure Enclave. You have to manage them yourself, and they don’t come with the same high level of protection.

Apple will no longer support Encrypted HFS+ after Golden Gate. If you have an HFS+ volume you encrypted in a previous macOS release, this is the time to remove encryption or upgrade the volume to APFS. You can perform both operations in Disk Utility.

If you’re the only person who ever uses your Mac, none of this applies. Otherwise, you should know a few things about what sorts of access other people may have to your data.

First, if everyone uses the Mac via a single account—without having to log in and enter a separate username and password—all bets are off. Whatever’s available to you is available to everyone else. I’m not a fan of that arrangement. Ideally, every human who uses your Mac should have a unique username and password. (I might make exceptions for kids too young to type their own passwords. See how to set up safe user accounts on a shared Mac.)

But let’s say each person does have a separate account and password, and each one diligently logs out (or shuts down the Mac) after every session before the next person logs in. Then what?

How ownership and permissions work

macOS, as a variety of Unix, relies on the properties of ownership and permissions for each file. To oversimplify a bit, each file and folder has a designated owner—usually one of the individual account holders or the system itself—and a set of attributes assigned to it that specify who can access it, modify it, delete it, or execute it, in the case of files. (Apple adds a number of Mac-specific attributes on top of that.)

But there are owners and there are owners. macOS Standard account owners can access files, apps, and folders in all public places, like the system-wide Applications folder, but they can modify and add items only in specific locations: their own home folder (/Users/username) and the Shared folder in the main /Users folder. No other standard user can view files in any other users’ home folders, except the default Public folder, which is read-only and has a Drop Box item (not Dropbox, the service) that other users can drag items into, but then not see afterwards (write-only). For day-to-day segregation of one person’s data from another, this system provides a reasonable barrier.

An administrator can assign additional access to all non-system files and folders by changing ownership to a user, creating a group and providing group read/write access to a folder, or changing permissions to make things readable and modifiable by anyone with an account.

Where the barrier breaks down

But that reveals the weakness, no? An administrator has “root” access, which is the top-level permission holder in Unix. Anyone with an administrator account and working knowledge of the Unix command line can access everyone else’s files by opening the Terminal app in /Applications/Utilities, entering sudo -s, and supplying the administrator account’s password.

They can also restart in recovery mode, and use Terminal there to avoid any safeguards or monitoring tools that might be installed in macOS. With an Apple silicon Mac, an administrator can share the entire Mac as a volume on another Mac via macOS Recovery, too.

Standard users also have some options to get around the protections that should prevent them from seeing other files:

• Filching your password: Anyone who knows or can guess your login password can log in as you and access all your files. Of course, you have a terrific password that you’ve kept completely safe from everyone else, right? Fine, but there are still other problems.
• Attach your Mac’s startup drive to another Mac as an external drive: If you start up your Mac from an external drive someone could attach that drive to another Mac to which they have administrator permissions and access all the files on it. If it’s protected with FileVault, they only have to have an account enabled for FileVault on the original Mac and know the password. While other users’ files appear locked when the Mac’s drive is mounted, they can be copied over and unlocked by entering an administrator account password on the destination Mac.
• Can’t attach volumes and other stuff while locked: Apple lets you require approval to attach new peripherals, SD cards, and other accessories to your Mac. See the Mac settings worth changing. If your Mac is locked, nothing can be approved.
• Connect your Apple silicon Mac to another Mac: Mac Sharing Mode is a feature introduced with Apple silicon Macs to let you mount one Mac as a volume on another Mac. Mac Sharing Mode turns a Mac into a file-sharing volume, instead of appearing as an externally connected drive. (This is functionally equivalent to, but less risky than, the Target Disk Mode available on Intel Macs.)

To use Mac Sharing Mode, connect an Apple silicon Mac to another Mac of any vintage with a USB or Thunderbolt cable. Restart your Mac in recovery mode, choose Utilities > Share Disk, and then select the volume to share. On the other Mac, the sharing Mac appears as a network volume.

In addition, someone who has access to backups of your files on mounted or unencrypted volumes or drives can likely access all of them without file ownership and permission getting in the way.

For all these reasons, the only safe assumption is that anyone else who has an account on your Mac or physical access to it could conceivably access your files. Although your data is fairly safe from casual access by nontechnical users, you should not think of ownership and permissions as a significant roadblock.

Moral of the story: Don’t give other people’s accounts administrator access if you don’t trust them and you can prevent giving them such privileges.

If you can’t, another option is to use encrypted disk images or volumes in which you keep the password to yourself. You can use the Finder to encrypt volumes and Disk Utility to create encrypted disk images; see how to turn on FileVault and encrypt your Mac. Unmount these disks when they’re not in use.

Many apps have startup activities you can manage. This includes launching an app when you log in and components of apps launching to run in the background continuously. From a security perspective, you should know what’s launching and occasionally check to see whether anything new has appeared that you’re unaware of.

Login items

Apps can add themselves to a list of items that open when you log in to your account. You can also add items manually. This Login Items list is unique to the current user logged in. It’s located in System Settings > General > Login Items & Extensions.

Your Mac uses a notification to let you know whenever an app adds itself or a component to the Login Items list.

You can take several actions on the items in this list:

• Control-click/right-click: This reveals the Show in Finder option. Choose it, and the enclosing folder appears with the item selected.
• Remove: Select one or more apps and click the minus button to remove them. There’s no prompt—it just happens.
• Add: Click the plus button and then select one or more apps, documents, or network servers to open or mount at launch.

With Siri AI active in Golden Gate, the top item is Ask Siri, as with some other contextual menus, where you can ask or type in something like “What is Pastebot?” to know what a particular login item does or is. Unfortunately, you can’t just ask “What is this?” even though it’s on a contextual menu—Siri just replies with details about Login Items.

If you want to prevent all login items from launching, you can do so temporarily in one of two ways:

• With a required user login: On the login screen, hold down the Shift key when clicking the login button. Keep holding down Shift until you see the Dock appear.
• With an automatically logged-in user: Restart your Mac. Hold down the Shift key when the progress bar starts and release after you see the desktop appear.

Background activity

macOS also gives you insight into and control over components of apps that are set to run in the background. First, you’re alerted when an app installs them.

Then, you can find a list of these items in System Settings > General > Login Items & Extensions under the Background App Activity heading (or App Background Activity in Tahoe and earlier). The list provides additional information under each item that can be useful. In Golden Gate, the labels explain the item’s status, noting whether it is currently running in the background. If it ran in the background within the last week, the label notes how long ago that was.

In Tahoe, the label provided one of three pieces of information: how many components the background item represented (typically “1 item”), how many accounts it affected on multi-account Macs with an item breakdown (“5 items: 2 items affect all users” as one example), or whether it was from an unknown developer, typically the case when the app that installed it was no longer installed and the background item was orphaned.

Items that are installed without the full information required by Apple are shown with a magnifying glass button. Click it, and it opens the component in the system or user Library folder where it lives.

While you can’t remove background items via this interface, you can enable and disable them. When you disable background items, you’re prompted to authenticate with Touch ID or your password.

Launch components are divided into daemons, which run at system startup before an account login, and agents, which launch after login. They’re found in folders named LaunchAgents and LaunchDaemons in /System/Library/ and ~/Library/.

If you want more insight into and control over what’s automatically running on any release of macOS, do yourself a favor and get Lingon X. The app shows everything that launches automatically—apps, scripts, daemons, agents, and the like. A free version lets you view all that; paying $23.99 unlocks editing and saving.

Automatic login

When you set up a new Mac, one of the first things you are prompted to do is create a user account for yourself by picking a username and a password. (Your Mac can have many such accounts, but it must have at least one.) By default, macOS logs in that initial user account automatically when you turn on or restart your Mac. That means you can get right to work without entering a password, and it’s the most convenient arrangement for Macs with a single user—especially if the Mac is kept in a secure place.

However, if anyone else (including a thief!) can get to your Mac, that automatic login becomes a problem, because your keychain unlocks automatically (see how the Mac keychain works) and all the files on your Mac are readily available.

If there’s a risk of someone gaining access to your Mac, you should disable this option by selecting Off. It’s found in System Settings > Users & Groups as a pop-up menu next to “Automatically log in as.”

Automatic login is incompatible with the FileVault security model and can’t be enabled when FileVault is turned on, which is by default starting in macOS 26. See how to turn on FileVault.

Which apps are allowed to launch

Apple hides their powerful Gatekeeper technology behind a menu selection. Gatekeeper prevents malicious software from easily taking root on a Mac, even on a naïve user’s computer (not you, to be sure). You can find the setting “Allow applications downloaded from” in System Settings > Privacy & Security. The options are App Store & Known Developers (the default) and App Store, which is “App Store Only” but not labeled that way explicitly.

I recommend leaving App Store & Known Developers selected unless you’re setting up a computer for someone who needs more handholding and protection. For a full explanation of how Gatekeeper works, see how Gatekeeper decides which Mac apps can run.

Limiting your apps to the App Store may also be the right choice at a very high level of risk, where people or organizations may expend substantial resources to subvert someone’s computer. Few people fall into that category.

You can select a different option whenever you like, but it only affects apps launching after that point. Switch from App Store & Known Developers to App Store, and you can still launch any third-party apps you had previously run, but no new non-App Store apps will validate.

If you have the launch option set to App Store and attempt to mount a disk image with a third-party app, or open a downloaded third-party app or one copied from a disk image you’ve approved, a Mac first tells you why it can’t mount or launch it.

However, if you then return to the “Allow applications from” location in your version of macOS, you see a helpful Open Anyway button along with an explanation of why the app didn’t launch in the Finder. That’s a little informal, but it makes sense: you made this choice, so why not?

An administrative macOS user can lock settings to App Store here, and a regular macOS user won’t be able to override it. See how to set up safe user accounts on a shared Mac.

Manage system extensions

Apple lets developers extend the system with, er, the appropriately named system extensions, which run with relatively few privileges, but give developers controlled capabilities. Apple mediates access to system extensions through System Settings > Privacy & Security.

Up until a few years ago, Apple allowed a deeper way to modify core functions, but removed that method seemingly because of security concerns.

If you have no extensions installed and never install software that requires them, you will never see extra information there, and you don’t have to interact with those parts of the pane.

If you have an Apple silicon Mac, you’re blocked from using system extensions without first enabling Reduced Security for your system as described in how macOS protects its own system files. Read that first: the mode changes your Mac’s risk profile.

After you run the installer, a note appears with a button in System Settings > Privacy & Security. Click Details and you see a list of all system extensions.

Note that all the switches are disabled—you can’t take action here. Click OK, and, despite not seeming to have done anything, a system extensions cache rebuilding dialog appears. Finally, you’re typically prompted to restart in a non-modal dialog: you can’t opt out of restarting.

Because Apple requires no standard for removing a system extension, you could wind up with old ones littering your Mac and no sure way of what to do next. Sequoia added a distinct improvement in System Settings > General > Login Items & Extensions. You can view the list using By App or By Category. In both cases, the list mixes simpler macOS extenders (like additions to the contextual menu in the Finder or Quick Look) with system extensions. To disable an extension, click the info button for an app or a category, like Fantastical or Network Extensions, and then disable it.

However, if you want to uninstall a system extension, first choose By Category. Then, for a category with system extensions, like Camera Extensions, a More button appears for each item. Click that to reveal a menu from which you can choose Delete Extension. You’re warned when you disable or delete an extension that the extension may continue to operate until after a restart.

If you can’t find the item you’re looking for in that list, open Terminal and enter systemextensionsctl list and press Return.

The resulting output shows all system extensions and where you need to go to find them in the Extensions list. This list tells you exactly which Extensions category contains each component.

to find extensions’ configuration location.

Start by trying to find an app’s uninstaller or instruction on its website. Failing that, turn to Lingon X to dig out old agents, daemons, and extensions. It may not be able to help with all system extensions.

When you delete a file by putting it in the Trash and then emptying the Trash, you might think it’s somehow gone forever. But file deletion ironically doesn’t erase the file from your drive. It simply makes a change to the disk’s catalog indicating that the space occupied by that file is available and can be overwritten with something else if and when necessary.

As a result, even if you’ve deleted a file, someone using file-recovery software could potentially undelete it later, as long as no other file has been stored in exactly the same spot since then. (That someone may be you if you accidentally deleted the file and don’t have a backup.)

Hard drives may eventually overwrite the deleted file’s freed-up storage with new data, but that isn’t a guarantee that the previous file can’t be recovered. With specialized equipment, it’s sometimes possible to retrieve old versions of files that have been overwritten one or more times with new data. It’s painstaking, technically challenging, and expensive work—which means it would happen only when the stakes are quite high—but it can be done.

With an SSD, it’s even harder to ensure data is gone for good: SSDs use wear leveling, which spreads your data out all over an SSD, as opposed to the specific physical locations that are mapped on an HDD. Each memory cell in an SSD has a maximum number of times in its usable life that it can be erased and rewritten before it fails. Wear leveling ensures that the last previously written-to location is the least likely to be overwritten soon relative to any other location that’s available on the drive. SSDs also employ trim, which tells the controller that a given location is no longer able to be erased. With even more expensive gear than required for HDDs, data can be retrieved to an alarming extent from SSDs.

The good news is that with an Apple silicon Mac, all data on the startup volume is also encrypted by default. You only need to consider external SSDs that you use for storage.

If you’re still using external hard drives, you could conceivably securely delete removed file portions, but Apple dropped a feature for that years ago. However, you can encrypt external HDDs and you can securely erase them before getting rid of them using Disk Utility:

1. Open Disk Utility, select the drive or volume, and click Erase.
2. Click Security Options.
3. Move the slider to the desired level of security and click OK, then click Erase. The slider has four notches:
   • Fastest: Regular erase, which doesn’t overwrite the data.
   • One-pass: Overwrite the data once with zeroes.
   • Three-pass: Overwrite the data three times, twice with random data and once with non-random data.
   • Most Secure: Overwrite the data seven times, meeting a U.S. Department of Defense standard.

The three-pass and Most Secure options can take a long time, and are necessary only in extreme cases, but if you want to make it all but impossible for someone to recover a file, you can.

Have the drive destroyed instead

Removable and external SSDs and HDDs can be sent out for secure destruction to outfits that receive licenses or certifications from various organizations. This includes some electronics recyclers who will use a drive crusher right in front of you. Some will give you a certificate that confirms the drive was destroyed. This is bad for the environment, but may be a valid choice if you have any concern about non-FileVault-encrypted drives’ data.

Apple Pay on a second volume

Apple allows Macs with a Secure Enclave and Touch ID enabled to store Apple Pay card information, so you can make purchases in apps and via Safari directly with your fingerprint. There’s no need to use a separate device. Setting up Apple Pay is straightforward, and handled via System Settings > Wallet & Apple Pay.

The security situation you may encounter, however, is when you set up Apple Pay either with another account on the same Mac or on an external startup drive! In the former case, Apple warns you in a notification. In the latter case, when you restart from your primary startup volume, your Mac also alerts you.

I saw both the above errors after restarting from an external bootable clone, because macOS interpreted both conditions as true.

Whether you set it up with a separate macOS user or an external volume, you can reset Apple Pay to work with your current main account with your current volume. However, it involves several steps:

1. Open System Settings > Wallet & Apple Pay.
2. Click the Add Card button.
3. The Mac prompts you about changing back. When prompted, enter your password or use Touch ID to proceed.
4. Select the cards you want to use and click Next.
5. For each card, you will have to confirm details, such as entering your Apple Account password or the security code on the card. You will also have to accept terms and conditions for many cards, and receive two-factor authentication for some.

Even if Apple Pay is disabled, you can still use it in Safari by approving purchases on your iPhone or Apple Watch. Enable this option in Safari > Settings > Advanced, where you can select “Allow websites to check for Apple Pay and Apple Card.”