UPADTE (2020-06-27): most of the information below is still correct, but I also made a more detailed investigation and summary on the practicalities of cheap "ebay" licenses: license-types-and-ebay.md
Windows 10 is free to download, but after 1-3 months of usage, you have to get a license and prove it to Microsoft servers over the internet. This process is called activation.
How to download Windows 10 ISO for installation:
- Google for "Media Creation Tool" if you already have a working windows,
- Direct download: https://www.microsoft.com/en-us/software-download/windows10ISO,
You can use these ISO files for installation. If you want to use a
pendrive, use isohybrid on the downloaded ISO and then dd it to
/dev/sdx.
For installation, you can just skip the part when it asks for your key to get your trial/grace period. If in some situation you are forced to enter a product key (upgrades, special cases, whatever), you can try to use the so called "generic product keys" which you can Google for (it's legit, Microsoft created them for these situations).
Every working computer is different in some way: hardware configurations can be very-very different between machines (PCI bus device IDs, vendor+product IDs, UUID of motherboard, BIOS revision, etc.).
So MS basically has a hash function from the set of existing computers to some big-enough set (I guess 2^128 or 2^256).
When you start activation, they compute the hash and send the
following packet to the activation servers: (H(product_key), H(hardware)).
MS server stores a big database of these tuples and it has the following rules:
-
if
H(product_key)is not found, then activation is valid and the tuple is saved, -
if
H(product_key)is found, butH(hardware)is different, then the activation is shady and they either reject it or they allow a couple of number of reactivations (2-3). If they accept it, they save the newH(hardware), -
if they have rejected you in the previous point, you can just call in and they will allow it in exchange for wasting 10 mins of your time. The phoneline is fully automated, no human interaction needed. You have to promise, that you are only using your OEM license on one computer.
If the activation works based on only the second paragraph, then it
will say that "Windows is activated with a digital license". Which
basically means, that for this H(product_key), the H(hardware) is
stored on MS servers.
N/KN editions: the N and KN editions are european/korean court ordered versions with removed multimedia apps and so. You better aviod these editions, just unnecessary complication. The licensing is different, so if you somehow have a license for this, you have to install this version and then you can install the missing apps/codecs/apis from Microsoft for free. (Media Feature Pack for N and KN versions:: https://www.microsoft.com/en-us/download/details.aspx?id=48231)
Single Language: special edition of Home, where it is not allowed to change the system language after installation is finished. So there are no separate language licenses, you can still install english with a German single language iso, but you have to reinstall, you can't just change die Sprache.
OEM: an edition, where Microsoft's opinion is that you are not allowed to move the license to another computer once installed. It's not about experts or companies preinstalling your computer, you are perfectly allowed to buy OEM licenses (called System Builder), but you can only install it to one hardware. The Court of Justice of Europen Union decided on 2012-07-03 in the UsedSoft vs Oracle case that selling OEM software is legit (provided you delete the original software before selling it). It's also legal to export these licenses out of the EU.
Based on this decision there is now a big market on ebay.de, where you can basically buy Home/Pro licenses for <$5.
Most of these have to be phone activated (Microsoft doesn't like you of course, so they make it hard), but this process takes <10 minutes, can be done for free by calling the US number from hangouts and doesn't involve talking to humans or pleading your case, it's a fully automated robot. After phone activating a hardware once, later reinstallations on the same hardware don't require phone activation.
If you want to obey to the OEM rules, you can buy from the US/UK shops which really deliver to you (CD/DVD+sticker) and according to the rules, you can pick-up a laptop in Los Angeles for 5 days. These laptops are non-functional and they will be discarded if you don't pick them up. These licenses cost ~$20 + shipping (which makes them expensive).
US story: ebay shop with windows licenses and 1-2 hard drives.
Retail: edition that you can buy in shops from the shelves. Very-very expensive (~280 CHF for Pro), but gives you the right to do whatever you want with the stuff, reinstall as many times you want on as many different computers you want, provided that you only have one system installed at a time.
Anyone who has a previous product key, can upgrade one machine to the same edition (e.g. Windows 7 Home to Windows 10 Home). Officially this ended 2 years ago, in practice this has not ended and I don't think it will.
How is it implemented though?
When you first activate a Windows 10 with an old product key, then
Windows will store the H(hardware) for a H(generic_key), not your
H(product_key). These generic keys have the special property, that
they can be in the database many times without rejection, but in case
of rejection, you can't phone activate. So the only way to get into
the DB is with an old license key.
Officially, these free upgrades are only valid until the end of your machine's lifecycle, but there are two exceptions:
-
you can tie this license to your MS account and then you can make bigger hardware changes to your system and it's not clear what is a bigger hardware change exactly,
-
you can declare on the old machine, that you don't like the upgrade and you go back to windows 7, and then you move your windows 7 license, then you upgrade again on the new machine.
The license allows to run Windows inside VMs, but because the emulated
hardware is very peculiar, it's not known if it's possible to match
the H(hardware) of a previous real installation.
Therefore, in the worst case you will have to phone activate after the real machine to virtual move. This will also make it impossible to keep the real installation and use both. This is disallowed by the license agreement anyways.
It's well advised to keep your VM identity controlled, so you don't have to phone MS on every reinstallation, so make sure you have control over your VM's BIOS strings and UUIDs.
Use https://github.com/Superfly-Inc/ShowKeyPlus/releases
After phone activation Windows will say "Windows 10 is activated", but
you can't be sure that your H(hardware) is saved and therefore it
will work 2 years from now, when you want to reinstall.
Go to Settings, Activation; then change the product key to the generic product key of your edition. This will deactivate Windows, reboot. When reboot has finished, enter your real product key. After it finishes it will say the correct "Windows 10 is activated with a digital license" string.
I used them: https://www.ebay.de/usr/lizenzking, it was 4 EUR. I had to wait 15 minutes for the code.
They look more popular and they are cheaper: https://www.ebay.de/usr/svemars0 . They promise sending in 30 seconds.
OK, so now you learned that you can get a Pro license for 4 EUR, this means that you definitely want to upgrade your Windows Home laptop for 4 EUR and use BitLocker instead of the problematic VeraCrypt solution.
The problem is, that if you enter this cheap OEM code to the edition upgrade UI of Windows 10, then it will reject it, because it's an OEM code, so it's an impossible scenario, that you want to upgrade.
Solution: enter the generic product key and wait for the upgrade, then after reboot enter your specific product key for activation.
There is a protection for stupid users: upgrade is not accepted if activation is invalid, this is because if you upgrade from Home to Pro, it's impossible to downgrade, you need full reinstall. With the generic product keys, activation is invalid.
Solution: put your laptop into flight mode and enter the generic product key. Bring out your laptop from flight mode only after the upgrade has finished. The upgrade is really fast, takes one reboot and ~5 minutes. No installed programs or data was hurt.
Once the upgrade has finished (using a new 4 EUR code), you can use the original Home license in e.g. a virtual machine, where disk encryption is not needed.
Newer laptops which were presold with Windows will have a key embedded in the BIOS which is automatically used in a reinstall.
Under Linux you can dump these keys from /sys/firmware/acpi/tables.
It's in either the MSDM or in the SLIC table.
This is problematic, if you used that key for something else and you instead want to use another key. You could of course enter a new key after first boot in the Activation setting, but there is one peculiar scenario: you have Pro embedded in BIOS, but you want to install Home.
Solution: you have to create a special installation USB media, details: https://superuser.com/questions/1020961/prevent-windows-10-installer-from-using-the-preinstalled-serial-key-without-disa