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March 24th, 2009 UnpackSDC 1.1 – bits of heuristics

I didn’t have much time recently, but I finally updated sdc unpacker. Now it can decode new MS protection schema ;)

As many people noticed, unpacksdc didn’t work well with new sdc files. For some reason, MS decided to use additional ‘encryption’ for packed files. Although encryption is simple xor, the encryption key is not stored anywhere in the file. I spent few hours debugging original downloader to find out where it comes from and apparently it is stored in encrypted form in downloader executable along with proper sdc CRC32. So – it looks unbreakable, but that’s not completely true ;)

Unfortunately for MS, they used xor “encryption” with constant, 1 byte key, so why don’t we scan for known file types in the container and calculate the key ourselves? – That’s what unpacksdc 1.1 does!

Download link:

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39 Comments. Add your own

INDIA  |  March 30th, 2009 at 9:09 am

im getting this error when tryin to use this. then it closes:

Unhandled Exception: System.IO.FileNotFoundException: Could not find file ‘I:\en
File name: ‘I:\en_Virtual_PC_702.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, Int32 bufferSize, FileOptions options, String msgPath, Boolean
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access,
FileShare share)
at System.IO.File.OpenRead(String path)
at ☻.☻(String[] ☻)

Peter  |  April 1st, 2009 at 12:36 am

Hi there,
This multiple file will not decrypt any ideas. Error message This file is not SDC file or this format is not supported?

YKLAI  |  April 9th, 2009 at 6:48 pm

I got unpacked everything but it came out as a zip file inside just readme

Line102  |  April 13th, 2009 at 11:18 am

helo man!

Thank you for you brainery and hard work.

Not that you are a good coder but you are a good problem resolver.

Keep up a hard work!


Unpacksdc  |  April 18th, 2009 at 6:37 am

I don’t have any words to express my thanks. Probably i may have to find a good dictionary.

All your hard work are much appreciated. As Line102 said you are the real problem solver.

You are the man and I am your fan.

Mimmo97  |  May 2nd, 2009 at 6:02 pm

Please, can you publish the source code?
If you make UnpackSDC Open Source then we can contribute.


Ezaff  |  May 6th, 2009 at 3:08 pm

Thank you for your program:)

esha  |  May 17th, 2009 at 3:45 pm

G:\>unpacksdcN en_compute_cluster_pack_sdk_x86.sdc g:\
UnpackSDC 1.1 (c) imagi
SDC version: B4
Ranval: 3E7C
headers_size: 1
Filenames size: 66
Proper CRC32: 0 – files are encrypted, using heuristics to find encryption key
Skipping CRC check
Scanning for encryption key…
Can’t find known file type to calculate encryption key.

man,how to find encryption key.

Ikke  |  May 26th, 2009 at 11:06 am

Good job, bro. Anyway, it could do with a progress bar or smthg. Pritty boring to watch the cursor blinkin.

Rock  |  May 29th, 2009 at 3:13 am

Tres awesome.

Works perfectly on my Ubuntu system running under ‘mono’. Forget needing Windows for actually downloading the files through their silly system. For anyone using Linux, get yourself the latest version of ‘mono’ and run the unpacksdc.exe like normal.

Mr Jay  |  June 12th, 2009 at 10:50 am

Thanks for sharing!

roni  |  July 4th, 2009 at 9:17 am

i’v downloaded windows vista >>

but an error through the sdc unpacking :

UnpackSDC 1.1 (c) imagi
SDC version: B4
Ranval: C41C3506
headers_size: 1
Filenames size: 116
Proper CRC32: 480F32E7
Computing CRC32…
Computed CRC32: 412A8F76
Wrong CRC!. Hit Enter to exit…

praiwan  |  July 6th, 2009 at 5:46 pm

after i dl
and try , it working for me
i hope that i hear a good news soon from other too.


Nour  |  July 9th, 2009 at 2:24 am

I have problem when i download unpacksdc and try t open it ,it show error say “The Application failed to initialize properly (0xc000007b)….,i use framework 3.5 sp1 anybady can help me to find i get that error

visions_of_eden  |  July 9th, 2009 at 4:53 pm

Hi ,
Great tool.
Only a small bug.
If the SDC encrypted archive happens to have more than one file , each file with different extensions (say .ISO and .EXE for instance) your tool fails to decrypt first N-1 files . It seems that it tryes to decrypt alla files with the last xor key found , so if the files have different extenstions xor key is wrong.
Cound someone confirm ?
However great work !
A good idea would be to release source code public .

John Weis  |  August 13th, 2009 at 5:58 am

Hey Thanks for this! I just used this on a SQL Server download and it worked flawlessly! Thanks!

Rick Rice  |  August 13th, 2009 at 6:57 am

Hi, I’ve been waiting for you to update this lol,
Listen i’m a fairly good programmer in visual studio if you could email me the instructions on finding the encryption key i’ll right a visual version of this great program of yours.

Rick Rice  |  August 14th, 2009 at 6:33 am

ok problem , this is version B4 crc comes up as 0 which ya know isnt gonna match the crc check lol i’ve tried appending, copy /b and it’s a no go. i’ll try to download again just in case my connection got a hickup and i never noticed it.

Rick Rice  |  August 14th, 2009 at 6:00 pm

i had a bad download, unpacking works fine for files larger than 2G with B4 encryption key.

janjouf  |  August 18th, 2009 at 6:31 am





Eagle  |  August 21st, 2009 at 2:31 am

C:\Users\MasterEagle>unpacksdc Paperboys – Lonesome Traveller.sdc C:
UnpackSDC 1.1 (c) imagi
Usage: UnpackSDC [SdcFile] [OutputDir]
SdcFile – file to unpack
OutputDir – directory to unpack to
skipcrc – when specified, crc check will be skipped

hmmm, dosen’t seem to work on my files:(

this is music files and i have win7 x64.

any help whit opening those files will be great. i live in Norway an it is a file I’m geting from my telecommunication company.


file (can only be downloaded 10times so can’t find it, let me know;)):

webtraweller  |  August 23rd, 2009 at 6:16 pm

worked perfectly on this download / thanks for your work on that little gem :)

Mononucleose  |  August 24th, 2009 at 12:35 am

Wow, i think i love you! i mean, dont get me wrong, i’m not in love with you or anything. But your tool just blew my mind! I’ve been struggling with that dang ELMS downloader for the past 5 hours, it was always stopping at the CRC, it wouldn’t even start, it would just stall, and man, you got that shit done in like 2 minutes.

Thanks a lot!

MIckSW  |  August 24th, 2009 at 2:31 am


dzoska  |  August 24th, 2009 at 6:27 pm

wow, thanks a lot!! I love you, man.
I had the problem with crc checksum of w7 and your unpacker solve it!!!

Ahmad  |  August 25th, 2009 at 12:42 am

Thank you so much for your efforts but I have a problem !!!!!

I downlaoded the windows 7 rtm ,now I downloaded it twice and the msdn downloader can not unpack it!!
I did as you described and used your tool but it gives me “the file is not sdc or this format is not supported”!!
what can I do ?!

jump  |  August 25th, 2009 at 9:30 am


I get the error: “This file is not sdc file or this format is not supported”

Any ideas?

hedrox  |  August 25th, 2009 at 12:53 pm

It doesn’t work. I’ve downloaded both and, used ‘copy /b’ command to merge them, but unpacksdc 1.1 program gives me error “this file is not sdc file or this format is not supported”. I tried several times (downloading and merging) and nothing. What i’m doing wrong?

watsson  |  August 25th, 2009 at 1:33 pm

Unpacking en_windows_7_professional_x86_dvd_x15-65804.01.sdc . This file is not SDC file or this format is not supported. The original microsoft downloader stops at crc check. thats why i wanted to use your app.

Fantini  |  August 26th, 2009 at 5:56 am

Thanks you very much, I dowloaded a 4GB file 3 times, and I have many troubles, and this solve all my problems.

TY again!

Sky  |  August 27th, 2009 at 2:30 am


I have a problem… I have tried to unpack, but It doesn’t let me. I’ve already merged the two part, these to be exact:

and this is what I get:
UnpackSDC 1.1 imagi
This file is not SDC file or the format is not supported

can you plz help me?

Tim Cinel  |  August 27th, 2009 at 5:30 am

Still downloading an SDC but found this while I wait – thanks in advance :)

(By the way, I agree with the others that suggest you should open source this tool)

ADam  |  August 27th, 2009 at 8:24 pm

Please add msi signature detection, cince UnpackSDC fails to unpack if there is only one msi file packed…

testman  |  August 27th, 2009 at 11:07 pm

error: this file is not sdc file or the format is not supported

i download 3 times

Tim Cinel » Blog Ar  |  August 28th, 2009 at 2:09 am

[...] Bookmarked a link on Delicious. » UnpackSDC 1.1 – Unpack SDC file from MSDNAA download [...]

Bernhard  |  August 29th, 2009 at 2:22 am

thx so much for that piece of code!

I am a student and I get ms programm normally via the download client without a problem, but somehow with recent downloads it stopps inbetween, or at the CRC-check. So I dont get the iso, but the sdc only.

Your programm worked perfectly for me as long as I moved the files into a simple foldername. (did not work in the original folders. maybe because of length, or included spaces?!)


testman  |  August 29th, 2009 at 8:58 am

Yes all .02.sdc file of windows 7 professional in “open” server give the error:
This file is not SDC file or the format is not supported

thx for any advice

jcsanchez  |  August 29th, 2009 at 3:14 pm

C:\>unpacksdc c:\en_windows_7_professional_x86_dvd_x15-65804.01.sdc c:\temp\
UnpackSDC 1.1 (c) imagi
This file is not SDC file or this format is not supported.


Enyad  |  August 29th, 2009 at 4:08 pm

Have been trying to unpack the windows 7 professional file from a known site. However after i copy file 1.sdc and file 2.sdc and get file 3.sdc i try unpacking with the latest version 1.1 of unpackersdc (thank you so much for the program) but I get this message as well:

This file is not SDC file or this format is not supported.

Can you walk me through the steps again to solve this problem please? Thank you very much

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