I know all about Magic Jellybean Keyfinder and other solutions to find the key from within Windows. These are not what I'm after because the key they found is the OEM key, and I am trying to reinstall Windows 7 from a clean iso. I have a valid Certificate of Authenticity (COA) sticker with a unique product key on the bottom of the laptop, but it is partially rubbed off. Any tricks to deciphering the key?

  • 2
    Before trying the lead pencil idea (and maybe after it as well), try take a photograph with a high resolution camera and zoom in - ie like a digital magnifying glass. I've found this has helped me read otherwise impossible-to-see writing on chips.
    – davidgo
    Commented Feb 6, 2016 at 7:58
  • "the key they found is the OEM key" -- um, I thought all those stickers only have OEM keys too? Commented Feb 7, 2016 at 12:03
  • @grawity Nope, in my experience that sticker is a unique key (I have no source for this other than my own evidence). The first thing I do when I buy a windows laptop is blow away the bloatware-laden pre-installed image, and install fresh from an ISO.
    – Johann
    Commented Feb 9, 2016 at 0:55

2 Answers 2


First, through trial and error in the Windows activation dialog, I discovered that the only possible characters are these (others are rejected): 2 3 4 5 6 7 8 9 B C D F G H J K M P Q R T V W X Y

The real breakthrough was this comment from Tom's Hardware:

"Old School technique worked for me. Soft lead pencil go over faded area gently so you don't tear sticker and my digits appeared..."


Lightly rubbing with a soft (2B) lead pencil indeed clarified the characters I was missing.

  • Another trick to try is exhaling on the sticker. Condensing moisture may make the characters more obvious.
    – fixer1234
    Commented Mar 13, 2017 at 15:53

There is an other way to fix this by generating the possible product keys and testing them one by one. Based on the number of missing characters this could be a tedious work so I suggest you the following: download The Ultimate PID Checker which can read a text file containing one product key per line and check if it's valid. Generate the possible combinations by yourself or use a software for that. I had similar problem and I wrote a little program which does exactly that. I'm not near my computer now so I can't upload it anywhere though. Let me know if you need it. The number of possible combinations will increase with the number of missing characters. The checking process can take up more than a day but eventually you'll get back your product key. Which I recommend writing down to a paper and sicking under the battery so it will be safe.


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