How SLP and SLIC Works


I was searching around the internet and did not find a nice comprehensive explaination of how SLP and SLIC worked.  I’m talking about how Microsoft allows large OEM PC manufacturers (such as HP, Dell, Toshiba, etc) to activate every copy of Windows Vista and 7 machines without needing to do it online.  After all, if you are building thousands of machines a day, would you really want to connect every one of them online to activate them?

Unlike Windows XP, Vista and 7 requires activation.  While retail and OEM copies of Windows XP required activation, corporate editions and SLP OEM copies did not.

So Microsoft provided a way for major players in the PC industry to permanently activate Vista and 7 without going online at all.  How?

Well, since I couldn’t find anything online regarding SLP and SLIC except for how to exploit them (read: using it illegally to pirate Vista and 7), I decided to write a simplified “how it works” text file.  It was originally written to explain to my co-workers and boss how we can use this to save our limited and precious MAK volume license keys for the truly needy (read: PCs that never came with Windows 7 and older PCs).

This is perfectly legal as long as the PC you purchased came already pre-installed (and therefore already using a SLP license) copy of Windows Vista and 7.

How SLP and SLIC Works

SLP = System Locked Preinstallation
SLIC = System License Internal Code
OEM = Original Equipment Manufacturer
1. The OEM pays for SLP OEM license to Microsoft.

2. Microsoft provides the OEM a SLIC key in place of a CD key.

3. Microsoft provides the OEM a SLP certificate file.

4. The SLP certificate must be matched up to the SLP code embedded in the BIOS ROM (also provided by Microsoft).
As an OEM PC manufacturer, they can pre-activate Windows in mass without needing to activate manually over the internet.  They just need those three things to ensure that it is a valid license.

To recap, they would need:

1. SLP code embedded in the BIOS ROM.
2. SLIC key (in place of a CD key).
3. SLP certificate file (must match SLP code in BIOS ROM).

When all three conditions are satisfied, the Windows OS will be in a permanent activated state and be considered geniune.

Closing Thoughts

In the end, the consumer pays for a Microsoft Windows license with every OEM PC purchase.  When it’s time to reinstall Windows because of a malware infection, you should not be required to pay Microsoft again for another copy of Windows (say, going to a store and buying a retail copy, or going to NewEgg to buy an OEM copy).  You should be able to reuse the same license you already paid for when you bought the machine, especially on the same machine you are re-installing the OS to.

The OEM license states that a copy of Windows can only be used on one PC, and it cannot be transferred to another.  This is why OEM licenses are cheaper than the retail versions (which allows the customer to transfer the license to another PC).  This SLP and SLIC method of activation, should force everyone to comply in theory.  However, as stated above, there are many sites I found when searching for this topic that chose to use this method in nefarious ways.

How does this even work when one of the ingredients to make this all work requires code in the BIOS ROM?  The other two (SLIC key and certificate) are easy to get – anyone can get to them by searching through the files of a properly activated OEM PC.  This is how the “community” found them.  The BIOS ROM is a bit trickier.  One way is to modify your firmware to include the SLP code.  This is dangerous, and not all firmware can be modified.  If the Frankenstien didn’t work, you would brick (render useless) your PC or laptop.  A safer way is putting the SLP code on the hard drive, and make it load before the OS even loads.  However, since it is on the hard drive, there is a risk that it can get corrupt or Microsoft detecting it in the future.

I wouldn’t recommend either way as a professional, but it’s definately an interesting concept to kick around.  However, the reason behind this article was for people who buys big-box PCs that already came with Windows Vista or 7 who find themselves needing to re-install Windows due to malware or file corruption.

As you noticed, I didn’t go indepth on how to do this step-by-step.  They can be found on the internet elsewhere.  If the guides dissapear one day, I will go ahead and write one up, but for now, I don’t see a reason to duplicate the work others have done.


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