I need to apply for a Windows 8 upgrade for my laptop, for which I need the Windows 7 license key on the underside of the laptop.

Because Microsoft decided in their infinite wisdom to create license labels that wear off, and I cannot read my license key clearly, it means I can’t register my laptop for the windows upgrade offer using an automated process.

By holding the laptop at an angle to the light I have been able to verify most of the code but several of the letters are ambiguous (thanks again Microsoft for using easy to misread characters in your label).

I have the following (obfuscated) license key,

MPP6R-09RXG-2H[8B]MT-[B8]K[HN]M9-V[6G]C8R

where the characters in square brackets are ambiguous, so it is either 8 or B, B or 8, H or N, 6 or G.

Making 16 combinations.

Is it appropriate to generate the possible permutations of this license key using itertools or is there a better way?

I got the correct key with thanks to the contributors. A very convenient way to check if the key is valid is by using the Windows 7 product key checker.

Disclaimer: Yes, I know that this is not Python code. It just popped into my mind and I simply had to write it down.

The simplest way is the use of shell expansion:

$ echo MPP6R-09RXG-2H{8,B}MT-{B,8}K{H,N}M9-V{6,G}C8R
MPP6R-09RXG-2H8MT-BKHM9-V6C8R
MPP6R-09RXG-2H8MT-BKHM9-VGC8R
MPP6R-09RXG-2H8MT-BKNM9-V6C8R
MPP6R-09RXG-2H8MT-BKNM9-VGC8R
MPP6R-09RXG-2H8MT-8KHM9-V6C8R
MPP6R-09RXG-2H8MT-8KHM9-VGC8R
MPP6R-09RXG-2H8MT-8KNM9-V6C8R
MPP6R-09RXG-2H8MT-8KNM9-VGC8R
MPP6R-09RXG-2HBMT-BKHM9-V6C8R
MPP6R-09RXG-2HBMT-BKHM9-VGC8R
MPP6R-09RXG-2HBMT-BKNM9-V6C8R
MPP6R-09RXG-2HBMT-BKNM9-VGC8R
MPP6R-09RXG-2HBMT-8KHM9-V6C8R
MPP6R-09RXG-2HBMT-8KHM9-VGC8R
MPP6R-09RXG-2HBMT-8KNM9-V6C8R
MPP6R-09RXG-2HBMT-8KNM9-VGC8R

from itertools import product
for perm in product('8B', 'B8', 'HN', '6G'):
    print 'MPP6R-09RXG-2H%sMT-%sK%sM9-V%sC8R' % perm

Another way to generate the combinations

>>> ['MPP6R-09RXG-2H%sMT-%sK%sM9-V%sC8R' % (a, b, c, d)
...  for a in '8B' for b in 'B8' for c in 'HN' for d in '6G']
['MPP6R-09RXG-2H8MT-BKHM9-V6C8R',
 'MPP6R-09RXG-2H8MT-BKHM9-VGC8R',
 'MPP6R-09RXG-2H8MT-BKNM9-V6C8R',
 'MPP6R-09RXG-2H8MT-BKNM9-VGC8R',
 'MPP6R-09RXG-2H8MT-8KHM9-V6C8R',
 'MPP6R-09RXG-2H8MT-8KHM9-VGC8R',
 'MPP6R-09RXG-2H8MT-8KNM9-V6C8R',
 'MPP6R-09RXG-2H8MT-8KNM9-VGC8R',
 'MPP6R-09RXG-2HBMT-BKHM9-V6C8R',
 'MPP6R-09RXG-2HBMT-BKHM9-VGC8R',
 'MPP6R-09RXG-2HBMT-BKNM9-V6C8R',
 'MPP6R-09RXG-2HBMT-BKNM9-VGC8R',
 'MPP6R-09RXG-2HBMT-8KHM9-V6C8R',
 'MPP6R-09RXG-2HBMT-8KHM9-VGC8R',
 'MPP6R-09RXG-2HBMT-8KNM9-V6C8R',
 'MPP6R-09RXG-2HBMT-8KNM9-VGC8R']
>>> 

How about using itertools and functools at the same time?

>>> from operator import mod
>>> from functools import partial
>>> from itertools import product
>>> map(partial(mod, 'MPP6R-09RXG-2H%sMT-%sK%sM9-V%sC8R'), product('8B', 'B8', 'HN', '6G'))
['MPP6R-09RXG-2H8MT-BKHM9-V6C8R', 'MPP6R-09RXG-2H8MT-BKHM9-VGC8R', 'MPP6R-09RXG-2H8MT-BKNM9-V6C8R', 'MPP6R-09RXG-2H8MT-BKNM9-VGC8R', 'MPP6R-09RXG-2H8MT-8KHM9-V6C8R', 'MPP6R-09RXG-2H8MT-8KHM9-VGC8R', 'MPP6R-09RXG-2H8MT-8KNM9-V6C8R', 'MPP6R-09RXG-2H8MT-8KNM9-VGC8R', 'MPP6R-09RXG-2HBMT-BKHM9-V6C8R', 'MPP6R-09RXG-2HBMT-BKHM9-VGC8R', 'MPP6R-09RXG-2HBMT-BKNM9-V6C8R', 'MPP6R-09RXG-2HBMT-BKNM9-VGC8R', 'MPP6R-09RXG-2HBMT-8KHM9-V6C8R', 'MPP6R-09RXG-2HBMT-8KHM9-VGC8R', 'MPP6R-09RXG-2HBMT-8KNM9-V6C8R', 'MPP6R-09RXG-2HBMT-8KNM9-VGC8R']

http://www.magicaljellybean.com/keyfinder/

The Magical Jelly Bean Keyfinder is a freeware utility that retrieves your Product Key (cd key) used to install windows from your registry. It also has a community-updated configuration file that retrieves product keys for many other applications.

Just run it on the install you want the key for.

If you use the Windows Anytime Upgrade option directly from within Windows 7, then you do NOT need to know what the license key is.

As long as the operating system is activated then Windows 8 will just overwrite the existing operating system and place everything from Windows 7 into a “Windows-old” folder which you can delete unless you need a file or something.

The Windows upgrade process looks for an activated Windows operating system, even Windows XP would do as long as it is activated before installing the upgrade.

You will be emailed the Windows 8 license key when purchasing via the Anytime Upgrade. If you buy an upgrade from a store you will just get a license key and a download URL OR you just plug the key into Windows Anytime Upgrade and it will download and install itself.