Just in case someone has installed the HTC Viveport software and is curious about all the files of the games located in C:\ProgramData\HTC\Vive\ViveApps having an additional extension .vpk and scrambled content in them, that's the DRM encryption.
Luckily for you it's enough to launch a game to have full access to its decrypted content in real-time by simply looking at the .vpXXXX.tmp folder (it's a mounted volume) in %TEMP%.
So there is nothing to decrypt or custom tools or difficult steps, it seems really too easy.
FYI, you can also run the games by command-line:
"C:\Program Files (x86)\ViveSetup\PCClient\HTCVRMarketplaceUserContextHelper.exe" appid=478452e3-7355-442d-9389-55ee52a99ca2
Where 478452e3-7355-442d-9389-55ee52a99ca2 is just an example of the names of the folders in the ViveApps folder, it's the game VRoom that is almost 9Gb big (UE4 engine so you can extract its pak with my script).
Anyway this is just a note/placeholder topic in case someone wants to add something else, but I don't think many people use this software.