
Host Protected Area - octosphere
https://en.wikipedia.org/wiki/Host_protected_area
======
PaulHoule
Weirder than that, there is a second area on the disk which lets you do the
same thing

[https://en.wikipedia.org/wiki/Device_configuration_overlay](https://en.wikipedia.org/wiki/Device_configuration_overlay)

So there are two hiding places instead of just one.

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codezero
If you're curious, I think this is the original proposal from ~ 1996. It's
amazing to see all the old hardware vendors on these things. Gateway and
Maxtor are dead now (Maxtor is on the ATA-3 specification). I like that this
covers two pretty common use cases. I wonder if the current "sleep" technology
of computers does this with the RAM, or if they use another more modern
mechanism.

[http://t13.org/Documents/UploadedDocuments/technical/d96137r...](http://t13.org/Documents/UploadedDocuments/technical/d96137r0.pdf)

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varjag
> _HPA can be used by various booting and diagnostic utilities, normally in
> conjunction with the BIOS. An example of this implementation is the Phoenix
> FirstBIOS, which uses Boot Engineering Extension Record (BEER) and Protected
> Area Run Time Interface Extension Services (PARTIES)._

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arcboii92
I thought it was interesting that BEER redirects to this page.

[https://en.wikipedia.org/wiki/BEER](https://en.wikipedia.org/wiki/BEER)

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Someone1234
I didn't realize that Wikipedia was case specific:

[https://en.wikipedia.org/wiki/Beer](https://en.wikipedia.org/wiki/Beer)

Vs.

[https://en.wikipedia.org/wiki/BEER](https://en.wikipedia.org/wiki/BEER)

~~~
jcranmer
It's not 100% case-insensitive: the first character cannot be lowercase, so
[https://en.wikipedia.org/wiki/a](https://en.wikipedia.org/wiki/a) and
[https://en.wikipedia.org/wiki/A](https://en.wikipedia.org/wiki/A) are the
same article.

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rdtsc
If you're wondering if NSA or others are using it for their purposes, yes,
they are:

[https://www.schneier.com/blog/archives/2014/02/swap_nsa_expl...](https://www.schneier.com/blog/archives/2014/02/swap_nsa_exploi.html)

Warning: contains TS classification markers. If you have clearance you might
not want to click that.

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wmf
HPA was also a good way to overprovision SSDs for better write performance
before TRIM existed (although today's SSDs are so fast I would no longer worry
about overprovisioning).

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sebazzz
Samsung Magician still recommends overprovisioning, even for the newer NVME
SSDs.

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rzzzt
I think Magician just leaves 10% free at the end by changing the partition
size, it does not seem to set a HPA or use DCO. If you started with a secure
erase/factory clean SSD, those blocks will be marked as unused and the garbage
collection algorithm can play Sokoban with them however it wants.

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acoye
I mean if you wanted to go full tinfoil hat, that thing hits the spot.

~~~
penagwin
If you're trying to hide something then that's a TERRIBLE place to put it.

I'd highly recommend something like veracrypt where you can encrypt a
container, and the container may or may not have another part encrypted with a
different password - you don't know until you enter the correct password for
the hidden section.

