How does macOS meet NIST 800-88r1 'Purge' requirements on devices without EACS, specifically regarding obliteration behavior?

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Level 1

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How does macOS meet NIST 800-88r1 'Purge' requirements on devices without EACS, specifically regarding obliteration behavior?

Hi all,

I'm working on aligning macOS device decommissioning with NIST 800-88 Revision 1 Purge requirements and need clarification on certain fallback scenarios.

On supported devices, Erase All Content and Settings (EACS) performs cryptographic erasure by securely destroying encryption keys, satisfying the Purge requirement. The uncertainty arises with devices that either don't support EACS (due to hardware or OS limitations) or where EACS can't be triggered remotely via MDM.

From Apple's limited documentation, I understand that the fallback in these cases is obliteration, but I haven't found detailed, official technical information describing exactly what obliteration does.

My specific questions are:

Does obliteration securely destroy encryption keys, effectively achieving cryptographic erasure?
Or is obliteration simply a wipe of the physical storage, without guaranteed destruction of key material?
For Intel Macs with T1 (pre-2018) or T2 (2018+) chips, as well as Apple Silicon devices, all with FileVault enabled, is obliteration sufficient to meet NIST 800-88r1 Purge requirements when EACS isn't available?

The environment includes Macs from 2016 onwards, both Intel (with T1/T2 depending on the year) and Apple Silicon, all with FileVault active.

If anyone has definitive technical resources or firsthand experience with the behavior of obliteration in this context, I'd appreciate your insight.

Thanks in advance.

MacBook (2017)

Posted on Jun 25, 2025 4:11 AM

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Answer 1

Camelot

Level 9

58,455 points

Jun 25, 2025 11:04 AM in response to xishie

I can't find a specific reference off-hand, but I do recall digging into this a while ago (when I worked in a field that cared :) )

Short version is that when using FileVault, obliteration does destroy the keys, thus rendering the data unrecoverable, and is considered compliant with the NIST guidelines.

There are some differences in the specific implementation between T1/T2/Apple Silicon, but from a storage/erasure standpoint they all amounted to the same thing as far as rendering data unrecoverable.

I do remember that this took some digging to surface, since Apple don't discuss this level of detail on their public sites. It helps if you have an account manager who can help connect you to the right resources. I'll keep digging and see if I can find the references.

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Answer 2

xishie Author

Level 1

4 points

Jun 26, 2025 2:10 PM in response to Camelot

Hey Camelot,

Appreciate the response, that lines up closely with what I’ve been piecing together as well.

I did some digging on my end too and managed to find a few older Apple Platform Security whitepapers. While they don’t spell everything out directly, reading between the lines, I came to the same conclusion you mentioned.

From what I understand:

If a Mac has a Secure Enclave, cryptographic erase is achievable under certain conditions:

That includes Macs with a T2 chip or Apple Silicon natively

On T1 Macs, cryptographic erase is only possible if FileVault is enabled, since without full disk encryption, there’s no key to destroy

It also makes sense that newer Apple Silicon devices don’t rely on FileVault in the traditional sense, since hardware encryption is always-on, but for older Intel models, FileVault activation is definitely critical to ensure cryptographic erase is viable.

Like you said, Apple’s public documentation is vague on these details, so a lot of this comes from piecing together bits of info. If you do happen to dig up any specific references, I’d appreciate it. I’ll share anything else I find as well.

Thanks again for the input :)

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