Although it says that's recommended option if one is recycling the PC, I've not been able to find any documentation that details what's happening behind the scenes when that option is selected.  The closest 'documentation' I've been able to locate is the Windows 8 documentation here but that doesn't explain anything.

Where's the technical documentation on what Windows is doing when a user selects this option?
How secure/safe/reliable is it?

I certainly don't expect a 35-pass wipe; I'm doubtful its even a 3-pass wipe.
I also don't expect it to protect users of the feature from someone who has the resources to pay for professional data recovery services.  (IMHO: If its reached that point and they're that desperate to get to your potentially non-classified/non-sensitive information, you've got more serious issues to be concerned about!)

I'm happy to continue using, and recommending, products like DBAN, WipeDisk and the like, but it would be nice to know whether or not the built-in features are more than sufficient to protect against someone who knows how to actually use the common data recovery applications publicly available today.

• Edited by JuliusPIV Tuesday, May 26, 2015 6:25 PM

How does this relate to the Windows 10 Preview?

The Windows reset is by no means a secure cleaning of the system.  You will have to use a third party utility meeting DOD specs to accomplish a secure cleaning of any system, Windows or otherwise.

How does this relate to the Windows 10 Preview?

That's not a very constructive reply; to be candid its quite odd.  The feature is baked into Windows 10, so my query to you: Why wouldn't it be relevant to Windows 10 Insider Preview?

The Windows reset is by no means a secure cleaning of the system.  You will have to use a third party utility meeting DOD specs to accomplish a secure cleaning of any system, Windows or otherwise.

So, for sanity's sake we'll lay the cards out:

In Windows 10 under 'Settings' > 'Update & Security' > 'Recovery' exists a 'Reset this PC' option.

This option allows you to perform a reset at varying but specific levels:

• Keep my files - which "removes apps and settings, but keeps your personal files"
• Remove everything - which "removes all of your personal files, apps and settings.
  

When selecting the latter option, one is presented with two additional choices:

1. Just remove my files - which "[..] is quicker, but less secure" and should be used "[..] if you're keeping the PC."
2. Remove files and clean the drive - which "[..] might take a few hours, but will make it harder for someone to recover your removed files" and should be used "[..] if you're recycling the PC."
   
   

So, the question stands:  If Microsoft is offering this as an option, and has since Windows 8, what does the latter option actually do?

• Does it do a clean all?
• Does it do a format /p n?  If so, what is n?
• Does it 'detect' user data and try to write back 'random' data only to those blocks?  (Perhaps leveraging something like sdelete?  And if it is sdelete, how many passes?)
• Is it 'safe enough' that the above-average IT guy wouldn't be able to recover much of anything?
  
  

I don't expect that option to be bullet proof meaning impossible for:

• professional data recovery services to get anything
• some seasoned forensics team to recover the data
  
  

If one either has data of that caliber or is paranoid, and arguably rightfully so, then yes I would agree that a third-party utility, like the ones I already mentioned, would be the correct approach.  (Of course your data would likely already be encrypted to begin with so tossing the keys should be sufficient.)

But if that built-in option isn't safe or reliable to begin with, why is it included?  To provide a false sense of security?  Is the expectation that the machine is going from non-IT person to non-IT person and there's no concern if the recipient trying to recover anything?

The query isn't a challenge on the feature, nor am I suggesting it provides DOD 5220.22M grade wipe functionality.
Just seeking a deeper understanding of what it does, how it works and when one, the average home user, who this feature is likely aimed at, might want to consider using something else.

• Edited by JuliusPIV Tuesday, May 26, 2015 12:08 AM

Hi,

What's the meaning of your "security"?

If you mean the data lost, when you do any reset/refresh, it's recommended you backup all important data.

The option to choose whether you want to erase data quickly or thoroughly. If you choose to erase data quickly, some data might be recoverable using special software. If you choose to erase data thoroughly, this will take longer but it makes recovering data less likely.

Thanks for the reply!

What's the meaning of your "security"?

I don't know that defining "security" is going to help much here; if you ask 100 people to define "security" you'll get 100 different answers.

The option to choose whether you want to erase data quickly or thoroughly. If you choose to erase data quickly, some data might be recoverable using special software. If you choose to erase data thoroughly, this will take longer but it makes recovering data less likely.

That looks like a paraphrased statement from what's already mentioned in this post as well as what's 'documented' here.  Unfortunately, that doesn't get us closer to answering the questions of what's going on under the hood.

JPV,

I don't think there is absolutely security. This is a relative concept.

If your data is very personal and important, I suggest you consider destroy it physically.