version 1.2
21-Jan-2005
Ed Scherer

Input
Digital Product ID	Use upper or lower case hexadecimal characters and spaces.
Associations (optional)	Product name, computer name, etc., that you'd like to associate with this key. You can use  Enter  to force newlines, which will be preserved.
Output
Decoded Product Key (and Associated Info)	PRODUCT KEY:    ASSOCIATED INFORMATION:   This might make a nice label.

As of Windows XP and Windows Office XP, you're required to enter product keys when you install the software. These are typically provided on a label affixed to a CDROM case or other software distribution packaging. The product key is required for product activation, and activation is ultimately required if you expect to use the product for more than a few weeks.

Microsoft, though, has not provided you with any way to view your product keys once you have entered them. So it's easy to enter them once and then forget about them. Over time, your installation CDROMs and software packaging — and the critical little product key labels — have a way of wandering off. Then, sometime later — perhaps after an unfortunate event requiring reinstallation of your system software — you need the product keys once again, but you can't locate them. Another very common situation is that you've got a bunch of computers, and you can't remember which product keys correspond to which computers.

Rule 1: Keep your product keys. Keep a record of them: which product keys were used to install what software on what computer. Copy these records and keep a copy at another geographical location (disasters do happen). Maybe even affix a sticker containing them to your computer (this is often done for you by many computer merchants that resell preinstalled Microsoft products).

Reality Check: Rule 1, unfortunately, is often violated and it becomes necessary to find the product keys through other means: inspection of the product key information that actually is stored in the system in the Windows Registry, but in obfuscated form. You can't just easily view them — even with the Registry Editor — as you might hope.

Luckily, though, a number of tools are available to provide you with a way of viewing your product keys. This is one such tool. Its one and only function is to decode digital product IDs used by Microsoft for:

• Microsoft Windows XP family products
• Microsoft Office XP family products

and perhaps some other Microsoft products that use the same obfuscation mechanism.

It's a rather specialized tool for unusual circumstances, though, and should probably not be your first choice for most cases. Read on...

When You Should Choose Another Tool

When should you choose another tool? Most of the time, actually. If you just need to find the product keys for your currently-running Windows system, consider using Magical Jelly Bean Software's Keyfinder. Nice tool, and it works just fine as of Windows XP SP2. It's a small, single file, no-installation-needed executable (.exe).

When You Might Need This Tool Instead

Under one or more of the following circumstances, this tool might be a good option:

• you're trying to recover product keys off a system that's not currently bootable/runnable
• you understand the various techniques you might be able to use to hunt through an off-line registry (loading hives, etc.) and find the values to decode
• you're paranoid about running executables (like Keyfinder) you download off the Internet and would rather be able to inspect the code that's being used (note that you can view this tool's source code; everything's in JavaScript and HTML)

The actual case I encountered that motivated me to whip this up was a system with a failing — but not totally gone — hard drive. No longer bootable. The system's owner (who shall go nameless, oh, and, "Hi, Mom!"), alas, had lost or misplaced the original boxes containing the orange product key stickers. Luckily, I was able to copy the %windir%\system32\config\software hive, load it with the registry editor, retrieve the digital product ID values, and use this tool to convert them to product keys.

Various Microsoft products obfuscate (using a two-way hash) the product key and keep them in the Windows registry under values named DigitalProductID. Such values are located in the registry at the following registry key locations (and probably a number of others):

Windows XP

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
(and note that same ID might also be at
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Registration
and maybe some other locations)

Office XP

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\10.0\Registration\CLSID
where CLSID is a CLSID of the form, {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}, e.g. {90500409-6D54-11D4-BEE3-00C04F990354}.

Get the value to enter for Encoded Digital Product ID into the above tool as follows.

1. Invoke the Registry Editor (regedit) and navigate to the key you want (e.g., HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\Current Version in the example above)
2. Select the DigitalProductID value name. Then select menu option [View] [Display Binary Data]. This will bring up a dialog box entitled Binary Data. Note that this is a little safer than just double clicking the value name, which gives you another dialog box where you run a slight risk of accidentally changing the value.
3. The value you're looking for is the subsequence of 15 hexadecimal bytes starting at hexadecimal field offset 0034 and up to and including offset 0042. If you want, you can also provide the tool with the entire value and it will extract the 15 hexadecimal byte subsequence. Unfortunately, as of Windows XP SP2, the Registry Editor doesn't support  CTRL-C  or any other way to copy the value to the clipboard.

Ed Scherer, 21-Jan-2005