Prevent Visual Studio from encrypting files

Question

I was just shocked when I saw this dialog popping up, because I thought I was a victim of an encryption virus:

Using Process Explorer to see which process opened the dialog, I found efsui.exe and I verified the signature to make sure it was an official Microsoft product.

Next, I googled about this and I found the command cipher /u to find encrypted files on my disk. The result was

C:\Windows\system32>cipher /u
C:\Users\XXX\Documents\Visual Studio 2015\Backup Files\Form1.Designer.vb\~AutoRecover.Form1.Designer.vb.sln: Encryption updated.

and that's confirmed when opening the folder in Explorer.

I'm using Visual Studio for a long time, but it's the first time I opened a VB Form.

Is it common that Visual Studio encrypts files? Does it only happen for VB or is this due to some other VS update that was installed recelty? How to turn that feature off?

I tried:

• enter "encrypt" and "encryption" in Visual Studio's quick find box.
• finding an answer like this one about removable drives but my drive is C: and not removable.

Answer 1

I suspect this is a feature that project templates/extensions can enable:

From: http://www.visualmicro.com/forums/YaBB.pl?num=1362001590/0

In summary, a number of machinations of Win32 code produced .sln recovery files, none encrypted. A creation of an independent arduino project created an encrypted .sln recovery file within a a minute or so

In this case the Arduino template seems to have this particular flag (perhaps because it can store credentials (App Store IDs, private keys etc.)).

In my mind it's an excellent sign that Microsoft Visual Studio devs have thought of the possibility of leaking sensitive/confidential information in the "temporary" files that might even go roaming via the domain controller and profile replication.

As such, there doesn't seem to be a way to disable the feature (and rightly so). But you can always store your projects/application data on a filesystem that doesn't support NTFS encryption. As the name implies, this would likely be any other filesystem.¹

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¹ it's not impossible that any POSIX filesystems supporting extended attributes could also support this feature on Windows, but I haven't heard of it before