https://learn.microsoft.com/en-us/windows/win32/api/d3d11/nf-d3d11-id3d11videocontext-getencryptionbltkey
ID3D11VideoContext::GetEncryptionBltKey (d3d11.h) - Win32 apps | Microsoft Learn
Gets the cryptographic key to decrypt the data returned by the ID3D11VideoContext::EncryptionBlt method.
happsmicrosoftlearn