Recover lost XP product key from unbootable system

Back in January, I wrote a tip about how to recover the XP product key from a running copy of Windows, using a tool from Nir Sofer called ProduKey.

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This tool is a boon for legitimately licensed Windows users who have lost their license sticker and don't want to get burned. But what about people who have no license sticker and can't boot Windows to use ProduKey?

The folks at DagonDesign, a site that offers scripts, plug-ins, articles and other resources, describe a technique which, paired with a few of their own utilities, allows you to extract and decode the product key for a non-working Windows XP installation.

For this trick to work, you'll need to have access to the unbootable machine's SOFTWARE Registry hive (usually located in \%SystemRoot%\System32\config\software). The hive must also be loadable into Regedit. If it can't be read, you may want to try and recover a backup copy of the SOFTWARE hive from the System Restore archive on that computer.

The authors of this technique have provided two utilities for extracting the product key. The first tool allows a Registry hive to be mounted interactively; you need to have Regedit running when using this tool. (If you already know how to mount a hive and edit it, you won't need this.) The second tool, which runs as an executable or through a Web form (see their website), decrypts the hex-code version of the key and renders it as the 25-character keycode as found on the Windows license sticker.

This technique can be used on any legitimate XP installation with a license key; it doesn't matter if it's an OEM or over-the-counter edition of Windows. Needless to say, this technique should not be used to attempt to circumvent Windows's licensing restrictions, but only to recover a legitimately lost product key.

About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter, which is devoted to hints, tips, tricks, news and goodies for Windows NT, Windows 2000 and Windows XP users and administrators. He has more than 10 years of Windows experience under his belt, and contributes regularly to SearchWinComputing.com and SearchSQLServer.com.

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This was first published in November 2006

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