T2 Security Chip and FileVault

[kd1]

I would like to know more about the T2 security chip and exactly how it encrypts data on a Mac mini.

Specifically, I would like to know about the following scenario:


I purchased a used 2023 Mac mini M2 Pro off of eBay. I am unaware if the previous owner ever enabled FIleVault or not. I have had FileVault enabled since setting it up. Does FIleVault encrypt the entire drive, even sectors/blocks of written/deleted data from the previous owner? Or does it only encrypt data that is copied to the drive from the point onward since it was enabled? I know that data is encrypted by default due to the T2 security chip, but is there any possibility of any of the data from the previous owner being able to be recovered? I would like to make it to where all data from the previous owner is completely lost/erased/encrypted forever.

Can you “layer” cryptographic erases? For example, what happens if I purchase a used Mac mini with the T2 security chip, enable FileVault, and then erase the disk, lose the key, and reinstall MacOS? What would happen if the previous owner had done the same thing? Are there now two different “cryptographic erases” layered on the drive? Does my enabling of FileVault encrypt data that was added/deleted by the previous owner (assuming they never enabled FileVault)?

 

[Bigwaff]

M-series Macs don’t have a T2 security chip.

 

[Nermal]

While that's true, the rest of the post is probably still relevant. The M chip has (most of? all?) the functionality of the T2.

 

[Bigwaff]

While that's true, the rest of the post is probably still relevant. The M chip has (most of? all?) the functionality of the T2.

Perhaps it is relevant .. but I wasn’t about to presume anything considering the incorrect premise of the long post.

 

[quarkysg]

Can you “layer” cryptographic erases? For example, what happens if I purchase a used Mac mini with the T2 security chip, enable FileVault, and then erase the disk, lose the key, and reinstall MacOS? What would happen if the previous owner had done the same thing? Are there now two different “cryptographic erases” layered on the drive? Does my enabling of FileVault encrypt data that was added/deleted by the previous owner (assuming they never enabled FileVault)?

From what I understand, the key to decrypt your disk is store in the T2 or Apple Silicon SoC Secure Enclave. Upon erase, this key will be wiped and replaced with another key. I don’t believe it stores a history of keys, as that’ll be a security hole there. It is unlikely that new key generated will match exactly to previous generated key used on the same disk.

 

[kd1]

M-series Macs don’t have a T2 security chip.

I did not know this, thank you for clarifying. Do you happen to know whether the M-chip has the same functionality as the T2? does this basically mean that the M2 is “less secure” than a Mac with the T2 chip?

 

[kd1]

While that's true, the rest of the post is probably still relevant. The M chip has (most of? all?) the functionality of the T2.

Thank you for your answer.

How would you recommend performing a secure erase of a Mac mini that does not have the T2 security chip? I still want to completely eradicate ALL data from the previous owner.

 

[iStorm]

For Apple Silicon Macs (and Intel Macs with the T2 chip), the disk is always encrypted whether FileVault is enabled or not. Enabling FileVault adds another layer of security by requiring your login password before the boot-up process retrieves the key to unlock the disk. It does not re-encrypt the disk.

If you want to be absolutely sure no data from the previous owner exists, Erase your Mac and reset it to factory settings. This basically deletes the encryption key and creates a new one, which renders the existing data volume unreadable. (Macs have two volumes...a signed/sealed one for the OS, and one for user data. That is a whole separate topic I won't get into here, but this article explains it well.)

There is no need to completely wipe the disk and re-install macOS manually (the old-fashioned/traditional way) with these newer Macs. It is overkill and unnecessary, but you certainly can if it makes you feel better. The method above is much quicker.

Not sure what you mean by your last paragraph, but there is no "layering". Once the encryption key is gone, it's gone for good. There can only be one encryption key stored in the Secure Enclave or T2 chip at a time.

P.S. If you do you own additional research on FileVault, pay attention to what Mac or chip they're referring to. FileVault works differently on different Macs/chips. For example, on Macs with the T1 chip or older, it did go through and encrypt the disk since they weren't automatically encrypted like they are today on newer Macs.

 

[kd1]

For Apple Silicon Macs (and Intel Macs with the T2 chip), the disk is always encrypted whether FileVault is enabled or not. Enabling FileVault adds another layer of security by requiring your login password before the boot-up process retrieves the key to unlock the disk. It does not re-encrypt the disk.

If you want to be absolutely sure no data from the previous owner exists, Erase your Mac and reset it to factory settings. This basically deletes the encryption key and creates a new one, which renders the existing data volume unreadable. (Macs have two volumes...a signed/sealed one for the OS, and one for user data. That is a whole separate topic I won't get into here, but this article explains it well.)

There is no need to completely wipe the disk and re-install macOS manually (the old-fashioned/traditional way) with these newer Macs. It is overkill and unnecessary, but you certainly can if it makes you feel better. The method above is much quicker.

Not sure what you mean by your last paragraph, but there is no "layering". Once the encryption key is gone, it's gone for good. There can only be one encryption key stored in the Secure Enclave or T2 chip at a time.

P.S. If you do you own additional research on FileVault, pay attention to what Mac or chip they're referring to. FileVault works differently on different Macs/chips. For example, on Macs with the T1 chip or older, it did go through and encrypt the disk since they weren't automatically encrypted like they are today on newer Macs.

Thank you for this detailed answer.

I guess my hesitation was due to half baked knowledge on how HDDs and SSDs work. I was under the impression that even if you “deleted” something on either, that the data still remained somewhere on the drive until it was overwritten. My worry was that that was the case with the data from the previous owner of my secondhand M2 Pro. But you are saying that by following the instructions in the link above would make that data (if any) completely unreadable due to it having been encrypted from the start?

 

[leman]

I guess my hesitation was due to half baked knowledge on how HDDs and SSDs work. I was under the impression that even if you “deleted” something on either, that the data still remained somewhere on the drive until it was overwritten.

This is usually the case with SSDs, yes. But since the data is encrypted in flight by the controller, this data is not recoverable.

My worry was that that was the case with the data from the previous owner of my secondhand M2 Pro. But you are saying that by following the instructions in the link above would make that data (if any) completely unreadable due to it having been encrypted from the start?

Pretty much. The way these SSDs work is they don't need a secure erase, because you are not getting the data in any case. While you can in principle desolder the flash chips and read them, the data on flash itself is encrypted, so you won't get anything useful off it.

 

[MacCheetah3]

I did not know this, thank you for clarifying. Do you happen to know whether the M-chip has the same functionality as the T2? does this basically mean that the M2 is “less secure” than a Mac with the T2 chip?

The T2 chip functionality, including the Secure Enclave, is part of the design (i.e., integrated) of M-series SoC.

I guess my hesitation was due to half baked knowledge on how HDDs and SSDs work. I was under the impression that even if you “deleted” something on either, that the data still remained somewhere on the drive until it was overwritten.

SSDs operate differently than HDDs. Relevant to your concern is a process of automatic deletion:

The Importance of Garbage Collection and TRIM Processes for SSD Performance

In the world of SSD technology, the terms Garbage Collection and TRIM are often thrown around, but what do they really mean? In this article, we’ll look at Garbage Collection, how it works, how this relates to the Trim command, and how they both work behinds the scenes to optimize and prolong an...

www.kingston.com

Circling back...

Does FileVault encrypt the entire drive, even sectors/blocks of written/deleted data from the previous owner?

Simple answer: yes

I know that data is encrypted by default due to the T2 security chip, but is there any possibility of any of the data from the previous owner being able to be recovered?

Not in any practical sense. Even with the default encryption there are multiple keys. And part of (i.e., used to generate) one of those keys is a Unique ID (UID), which is a random number fused into the Secure Enclave.

Volume encryption with FileVault in macOS

In Mac OS X 10.3 or later, Mac computers provide FileVault, a built-in encryption capability to secure all data at rest.

support.apple.com

And this is even if any previous data remains following a reset/restore/reinstall and garbage collection.

 

[kd1]

For Apple Silicon Macs (and Intel Macs with the T2 chip), the disk is always encrypted whether FileVault is enabled or not. Enabling FileVault adds another layer of security by requiring your login password before the boot-up process retrieves the key to unlock the disk. It does not re-encrypt the disk.

If you want to be absolutely sure no data from the previous owner exists, Erase your Mac and reset it to factory settings. This basically deletes the encryption key and creates a new one, which renders the existing data volume unreadable. (Macs have two volumes...a signed/sealed one for the OS, and one for user data. That is a whole separate topic I won't get into here, but this article explains it well.)

There is no need to completely wipe the disk and re-install macOS manually (the old-fashioned/traditional way) with these newer Macs. It is overkill and unnecessary, but you certainly can if it makes you feel better. The method above is much quicker.

Not sure what you mean by your last paragraph, but there is no "layering". Once the encryption key is gone, it's gone for good. There can only be one encryption key stored in the Secure Enclave or T2 chip at a time.

P.S. If you do you own additional research on FileVault, pay attention to what Mac or chip they're referring to. FileVault works differently on different Macs/chips. For example, on Macs with the T1 chip or older, it did go through and encrypt the disk since they weren't automatically encrypted like they are today on newer Macs

I appreciate your response. Thank you for the info! Do you know if Ipads work the same way as this? I purchased a used ipad mini 6th generation from ebay and want to make sure it is securely erased as well, with no data lingering.

I also have an older gen 1 ipad pro that I would like to securely erase before selling, but I am not sure if the older ones had encryption enabled from the start like I understand the new ones to have.

 

[kd1]

This is usually the case with SSDs, yes. But since the data is encrypted in flight by the controller, this data is not recoverable.



Pretty much. The way these SSDs work is they don't need a secure erase, because you are not getting the data in any case. While you can in principle desolder the flash chips and read them, the data on flash itself is encrypted, so you won't get anything useful off it.

Great to know, thank you! Do you happen to know how often TRIM is activated on these newer Macs?

 

[kd1]

The T2 chip functionality, including the Secure Enclave, is part of the design (i.e., integrated) of M-series SoC.


SSDs operate differently than HDDs. Relevant to your concern is a process of automatic deletion:

The Importance of Garbage Collection and TRIM Processes for SSD Performance

In the world of SSD technology, the terms Garbage Collection and TRIM are often thrown around, but what do they really mean? In this article, we’ll look at Garbage Collection, how it works, how this relates to the Trim command, and how they both work behinds the scenes to optimize and prolong an...

www.kingston.com

Circling back...


Simple answer: yes


Not in any practical sense. Even with the default encryption there are multiple keys. And part of (i.e., used to generate) one of those keys is a Unique ID (UID), which is a random number fused into the Secure Enclave.

Volume encryption with FileVault in macOS

In Mac OS X 10.3 or later, Mac computers provide FileVault, a built-in encryption capability to secure all data at rest.

support.apple.com

And this is even if any previous data remains following a reset/restore/reinstall and garbage collection.

I am happy to know that filevault encyrpts all blocks/sectors of the drive, even previously deleted ones.

Do you happen to know if that is the case on older macs? I have a 2015 retina macbook with an ssd that I would like to wipe before selling, and want to completely eradicate all data/any chance of data recovery before selling it. Thanks!

 

[leman]

Great to know, thank you! Do you happen to know how often TRIM is activated on these newer Macs?

That's an internal detail of the storage controller. Maybe the Linux hackers who reverse-engineered Apple Silicon drivers would know. All I can tell you is that Apple's system is highly custom, they use standard protocols but extend and change them in ways that suits them best.

 

[MacCheetah3]

I am happy to know that filevault encyrpts all blocks/sectors of the drive, even previously deleted ones.

Do you happen to know if that is the case on older macs? I have a 2015 retina macbook with an ssd that I would like to wipe before selling, and want to completely eradicate all data/any chance of data recovery before selling it. Thanks!

Well, if you haven’t, you could enable FileVault, but do be aware:

After you turn on FileVault and the encryption begins, you can’t turn off FileVault until the initial encryption is complete. Encryption can take a long time, depending on the amount of data stored on your computer, but you can continue to use your computer as you normally do. After the encryption process is complete, you can turn off FileVault

If you get an alert message that encryption has been paused, your Mac may have detected a problem that could keep the encryption from completing successfully. For example, if your Mac notebook computer is not plugged into an electrical outlet, the encryption process may pause until the power plug is connected.

Apple doesn’t instruct (a need) to disable FileVault as part of the...

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

Reset your Mac to factory settings to prepare it for a new owner.

support.apple.com

However, there are claims it causes problems after an erase all or reinstall, for example:

What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

Reset your Mac to factory settings to prepare it for a new owner.

support.apple.com

I’ve never used FileVault, so I have no evidence either way. But as a note, password prompts and the like could be caused by not signing out of iCloud or forgetting to turn off Find My rather than due to FileVault. Again, I can’t confirm nor disprove. In other words, you might be pointlessly adding a lot of time in preparing your Mac for sale (i.e., enable fileVault, erase all or reinstall, see a password prompt on setup, need to re-setup the Mac, disable FileVault, then do another erase or reinstall).

 

[Mr.Fox]

I would like to know more about the T2 security chip and exactly how it encrypts data on a Mac mini.

Specifically, I would like to know about the following scenario:


I purchased a used 2023 Mac mini M2 Pro off of eBay. I am unaware if the previous owner ever enabled FIleVault or not. I have had FileVault enabled since setting it up. Does FIleVault encrypt the entire drive, even sectors/blocks of written/deleted data from the previous owner? Or does it only encrypt data that is copied to the drive from the point onward since it was enabled? I know that data is encrypted by default due to the T2 security chip, but is there any possibility of any of the data from the previous owner being able to be recovered? I would like to make it to where all data from the previous owner is completely lost/erased/encrypted forever.

Can you “layer” cryptographic erases? For example, what happens if I purchase a used Mac mini with the T2 security chip, enable FileVault, and then erase the disk, lose the key, and reinstall MacOS? What would happen if the previous owner had done the same thing? Are there now two different “cryptographic erases” layered on the drive? Does my enabling of FileVault encrypt data that was added/deleted by the previous owner (assuming they never enabled FileVault)?

There is no T2 chip in the M series chip
Yes, all information can be recovered 100% with expensive specialized software. Passwords, encryption won't help. It'll take a couple seconds to crack. A 512 Gb hard disk or SSD encrypted by FileVault decryptor will decrypt in about 20-40 minutes, depending on how much data.
Replace chip SSD with a new one, this will be a 100% guarantee that there will be no information from the previous owner. You will either have to unsolder the memory chips yourself or go to a repair shop.
There are many methods of deleting data, you do not have to use the built-in software.
The data will still be there if the previous owner reinstalled the operating system.

 

[Bigwaff]

The data will still be there if the previous owner reinstalled the operating system.

“Erase All Contents and Settings” will replace the current encryption key with a new key, effectively making any existing data irretrievable. There isn’t any specialized software I’m aware of that can recreate a deleted encryption key and use it to access any previously written data on disk.

 

[mr_roboto]

There is no T2 chip in the M series chip
Yes, all information can be recovered 100% with expensive specialized software. Passwords, encryption won't help. It'll take a couple seconds to crack. A 512 Gb hard disk or SSD encrypted by FileVault decryptor will decrypt in about 20-40 minutes, depending on how much data.

This post is so wrong that it's worth calling it out as lies to make sure people know it's that level of wrong.

Even the thing about T2 is wrong. Yes, technically, there's no separate T chip, but there doesn't need to be. T2 was just a derivative of A10, A10 is the ancestor of M1. M series chips have everything that a T2 did.

No, files cannot be recovered with expensive tools in little time. There is no known crack for the AES-256 algorithm Apple uses in FileVault. Because it's a 256-bit key, a brute force attack would probably take billions of years.

The password used to protect that 256-bit encryption key is a weakness because it's considerably lower strength than 256 bits, but Apple also used best practices here. They have a secure storage component which the system uses to retrieve the 256-bit encryption key based on the user's password. It rate-limits password guess attempts, and it also will destroy the key after too many failed guesses.

The result is that as long as you choose a good password that is not shared with anything else, FileVault is extremely secure. Furthermore, when you wipe a modern Apple device using the "Erase all content and settings" feature (or just try to guess the password too many times!), the AES decryption key is destroyed, meaning there's no way to recover data even if you know the password formerly used to unlock it.

 

[Mr.Fox]

“Erase All Contents and Settings” will replace the current encryption key with a new key, effectively making any existing data irretrievable. There isn’t any specialized software I’m aware of that can recreate a deleted encryption key and use it to access any previously written data on disk.

Expansion algorithms have been possible for a long time. It is used in forensic examinations since 2012. Here is the part that is open for review, the rest on request. https://www.passware.com/kit-forensic/

 

[Mr.Fox]

This post is so wrong that it's worth calling it out as lies to make sure people know it's that level of wrong.

Even the thing about T2 is wrong. Yes, technically, there's no separate T chip, but there doesn't need to be. T2 was just a derivative of A10, A10 is the ancestor of M1. M series chips have everything that a T2 did.

No, files cannot be recovered with expensive tools in little time. There is no known crack for the AES-256 algorithm Apple uses in FileVault. Because it's a 256-bit key, a brute force attack would probably take billions of years.

The password used to protect that 256-bit encryption key is a weakness because it's considerably lower strength than 256 bits, but Apple also used best practices here. They have a secure storage component which the system uses to retrieve the 256-bit encryption key based on the user's password. It rate-limits password guess attempts, and it also will destroy the key after too many failed guesses.

The result is that as long as you choose a good password that is not shared with anything else, FileVault is extremely secure. Furthermore, when you wipe a modern Apple device using the "Erase all content and settings" feature (or just try to guess the password too many times!), the AES decryption key is destroyed, meaning there's no way to recover data even if you know the password formerly used to unlock it.

Bright personality with premature verbal evacuation, shut your mouth to accuse of lying. Are you familiar with the criminal offense of defamation on the internet? Disappear into the mist.
How are you going to argue with that and accuse me of lying?
https://www.passware.com/kit-forensic/

 

[iStorm]

Bright personality with premature verbal evacuation, shut your mouth to accuse of lying. Are you familiar with the criminal offense of defamation on the internet? Disappear into the mist.
How are you going to argue with that and accuse me of lying?
https://www.passware.com/kit-forensic/

Do you understand how this works?

It scans the physical memory and extracts the encryption keys. It may work if law enforcement raided your house and your computer was still on since the key would be somewhere in memory.

Passware Kit scans the physical memory image file (acquired while the encrypted disk was mounted, even if the target computer was locked), extracts all the encryption keys, and decrypts the given volume.

As I'm sure you know, all contents of memory is lost after shutdown. It goes on to say that it's impossible to do an instant decryption if the computer has been turned off. It has to do a brute-force attack instead, which can take a long time. With a 256-bit encryption key, that would take millions of years using current computing technology.

NOTE: If the target computer is turned off and the encrypted volume was dismounted during the last hibernation, neither the memory image nor the hiberfil.sys file will contain the encryption keys. Therefore, instant decryption of the volume is impossible. In this case, Passware Kit assigns brute-force attacks to recover the original password for the volume, which is a time-consuming process.

https://support.passware.com/hc/en-us/articles/115002145727-How-to-decrypt-Full-Disk-Encryption

 

[chrfr]

Bright personality with premature verbal evacuation, shut your mouth to accuse of lying. Are you familiar with the criminal offense of defamation on the internet? Disappear into the mist.
How are you going to argue with that and accuse me of lying?
https://www.passware.com/kit-forensic/

Passware is exploiting a vulnerability in the T2 which can't be patched. It's not applicable to non-T2 or Apple Silicon Macs as those don't have the vulnerability and it's not decrypting FileVault itself.
T2 Mac security vulnerability: Passwords can now be cracked - 9to5Mac

With that said, it should be assumed that state actors can access whatever they need. General consumers have no need to be concerned about this– nor should they be concerned that some random person is going to have a copy of Passware's software kit, or others like it.

 

[Mr.Fox]

Do you understand how this works?

It scans the physical memory and extracts the encryption keys. It may work if law enforcement raided your house and your computer was still on since the key would be somewhere in memory.


As I'm sure you know, all contents of memory is lost after shutdown. It goes on to say that it's impossible to do an instant decryption if the computer has been turned off. It has to do a brute-force attack instead, which can take a long time. With a 256-bit encryption key, that would take millions of years using current computing technology.

https://support.passware.com/hc/en-us/articles/115002145727-How-to-decrypt-Full-Disk-Encryption

Why are you wigging out?
I knew you'd say that)))) The chess game begins It doesn't matter if the device is on or off. Whether it has a password or not.Whether the disk is encrypted or not. There are a huge number of devices and software that can extract information and do it effectively. Are you familiar with Blackbug Technologies, Inc? All the best for digital forensics.
Devices break down and are hacked in batches. There will be a tool. Judging by your logic, it is impossible to hack anything. However,criminologist are working and pulling out information

 

[chrfr]

Are you familiar with Blackbug Technologies, Inc? All the best for digital forensics.

I think you might mean Blackbag Technologies, which has been acquired by Cellebrite. In any case, again, these products aren't available to consumers and someone buying or selling a Mac has no need to be concerned about their use in this context.