[How to] extract .SDC file from MSDNAA

Update Nov 10th 2009

If you still have the latest .sdc file of Windows 7 Professional and are unable to mount/extract it, you should stop trying as you can now obtain Windows 7 Professional ISO from the official retail website. Here is the link to obtain your Windows 7 image file

If you are like me downloading files from a source that’s end with .SDC file. How to extract it? First thing first, what is SDC file?

The .SDC file format is a Secure Download Cabinet file. It is an encrypted and compressed file format for Internet delivery of the products. The product executable that is downloaded from ELMS decrypts and extracts the product. If you have an SDC file on your hard drive after downloading a product, the process has failed. Delete the SDC and try again.

Note that this kind file will only exist when you download from ELMS encrypted MSNDAA site. I got it from my school SFU’s MSNDAA website. They have the newest Windows 7 Professional available to download both 64 bit and 32 bit. You can download from the website or burn your own DVD. However, when I choose to download it from their website, I always getting an error code: SDC00400

My installer returns an error SDC00400 – Unable to complete download what is wrong?
The SDC00400 – Unable to complete the download error is typically caused by:

  1. an error in the configuration of the download package, usually due to a bad hosting location
  2. no Internet connection found
  3. Internet connection lost
  4. a firewall or proxy server between the client station and hosting location, or
  5. insufficient disk space to download.

Which means if I want to have it working I need to wait and download it from the official way, which I doubt will fix the connection or anything to do with the list above. So I ended up going to this site that offers the exact same file from the official MSNDAA.

Because the file is encrypted you can’t use any tool you normally use to extract it. I found this guy who wrote a program that can decode the encryption and extract the file, though he didn’t write much instruction on how to use the command utility exactly.

Correction: When you download the file from MSNDAA there will be 2 separate .sdc files you need to combine them together (same as other files over MSNDAA)



Rename them to 1.sdc and 2.sdc for easy command line file name entry.


Here I renamed the file into 1.sdc and 2.sdc make the new file called 3.sdc (for easier command line use)

Next You need to unzip the “unpacksdc” first, and then navigate to the same directory as your newly combined sdc file.

Type: unpacksdc [space] [sdc file name] [space] [output directory] (don’t enter bracket and space when using the command line)

On the image above I extracted the file named “en_windows_7_professional_x64_dvd_X15-65805.sdc” to C:\Download directory. (or 3.sdc instead of the full name, since you’ve already combine them in the previous step)

The total unpacked size for en_windows_7_professional_x64_dvd_X15-65805 is 3149108KB and en_windows_7_professional_x86_dvd_x15-65804 is 2443256KB

Enjoy! That’s it. This works for any other sdc files.

Download the latest unpacksdc here.


As one of our readers pointed out that all the problems you might experience after late Aug are the result of the change Microsoft did on the encryption.The guy who wrote the sdc unpacker is currently working on the new version that will also includes a UI for general public easy use. However, since the new unpacker hasn’t released. You may want to find some other alternatives to download the ISO file. (usually your school should also provide the ISO image file for you to burn as well)

Once again, if you luckily got it working, great. But if not, maybe come back another time to check this post. I will update it accordingly.

Jonathan Hu

Programming by day, Web Development, Canucks & Movies for spare time!
Co-founder of Next of Windows and a cool geek 🙂

Last updated: 12/23/2014

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salman amjad

it is giving error that this file is nt sdc file?????????????????


it failed “this file is not sdc file or this format is not supported”

I download windows 8.1 os

Fuck Microsoft

I fucking hate Secure Download Manager


Jonathan, where did you get the *.scd files? I downloaded my ones on mid september, and unpacksdc can’t handle them. I have to use this tool like many of you because the downloader doesn’t do it job correctly.


C:Downloads>unpacksdc 3.sdc C:Downloads
UnpackSDC 1.1 (c) imagi

Unhandled Exception: System.IO.FileNotFoundException: Could not find file 'C:Do
File name: 'C:Downloads3.sdc'
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, I
nt32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions o
ptions, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access,
FileShare share)
at ☻.☻(String[] ☻)

I Getting this error… When i use command to extract, my Windows 7 X64 say to me that program unpacksdc.exe stop working…

Can you help me pls?

Dean Pepler

please someone help me !!

i am trying to extract en_winxp_pro_with_sp2.sdc

just downloaded it last night

it keeps on giving me the error that is not a valid sdc file format ;’-(


Hi Vlaasa

from the error message I can tell that you either didn't create the 3.sdc or you don't have the “unpacksdc” in the same folder as 3.sdc

as I've mentioned at the beginning of my post, the unpacksdc is likely not working now. You can get your windows 7 professional ISO image from the link I posted here its from the official Windows retailer.

Hope that helps


Jonathan, i downloaded a windows 7 professional with service pack 1 but it has only 1 sdc file. What should I do in order to install it to my laptop?