Add GetLegacyGameKey

[Revadike]

SteamRE/SteamKit#1071

[Revadike]

🙀
That was quick!

[Revadike]

@DoctorMcKay rip, you forgot to add it to docs though

[DoctorMcKay]

🤦

[Revadike]

So, I just dumped all cd keys of my owned apps and there are a few bad/weird keys among them. Most of them are fine, but some are what seems like base64 encoded buffers. This happened for these apps:

• https://steamdb.info/app/236591
• https://steamdb.info/app/359600
• https://steamdb.info/app/359610
• https://steamdb.info/app/591121
• https://steamdb.info/app/783930

[DoctorMcKay]

Those are all Ubisoft games and they all activate with an API, so I'm guessing that's just the format they went with for those keys. Nothing says a key must look like XXXXX-XXXXX-XXXXX.

[DoctorMcKay]

Update from Discord:

I decoded the base64 but didn't get anything super interesting in the binary data
the first 4 bytes are 0x01 0x01 0x01 0x00 but beyond that I don't see a noticeable pattern
no steamid, for example
I'd thought maybe it would be an app ownership ticket given the LegacyKeyProofOfPurchaseTicket appdata key
https://steamdb.info/search/?a=app_keynames&type=-1&keyname=391&operator=1&keyvalue=
these all look like ubisoft games
it might just be something special valve did for ubisoft
I don't really understand why that would be necessary given encrypted app tickets are a thing, but ¯\_(ツ)_/¯