How Does Windows Know My Key Is Valid?

[Manage My Cables]

Right so I brought a Windows 10 key off kinguin.com a couple hours ago. I activated it on my new media pc about 5 minutes after purchase. At this point in time the pc had never been connected to the internet but accepted the key? How does my pc know the key is activated? 

[Godlygamer23]

The formatting perhaps.

[another random person]

4 minutes ago, Manage My Cables said:

Right so I brought a Windows 10 key off kinguin.com a couple hours ago. I activated it on my new media pc about 5 minutes after purchase. At this point in time the pc had never been connected to the internet but accepted the key? How does my pc know the key is activated? 

 

If the PC has accepted the key then it is most likely valid but if it fails to activate over the internet, then it probably isn't genuine.

[Naeaes]

There's a complicated math process done to the key during the offline validation. It's nowhere near this simple but just as an example it can convert the ASCII characters to binary, add them all up, multiply the result by four and see if the four middle digits are 0010. It then accepts it at face value if it adds up.

If hackers get a hang of that math algorithm, they can reverse-engineer it to generate valid keys. If windows didn't do an online lookup later on, or if there was a way to disable the online lookup, you'd get away with it. That's how keygens work. But to counter that, windows does do an online lookup as soon as you connect the machine to the internet. They see if your exact key is on a list of valid keys (whitelist) or if it's on a list of known leaked keys (blacklist) and go from there. 

[Manage My Cables]

5 minutes ago, Naeaes said:

There's a complicated math process done to the key during the offline validation. It's nowhere near this simple but just as an example it can convert the ASCII characters to binary, add them all up, multiply the result by four and see if the four middle digits are 0010. It then accepts it at face value if it adds up.

If hackers get a hang of that math algorithm, they can reverse-engineer it to generate valid keys. If windows didn't do an online lookup later on, or if there was a way to disable the online lookup, you'd get away with it. That's how keygens work. But to counter that, windows does do an online lookup as soon as you connect the machine to the internet. They see if your exact key is on a list of valid keys (whitelist) or if it's on a list of known leaked keys (blacklist) and go from there. 

Thank You very much for explaining that