You must uninstall previous Windows CNG SDK instances before installing this version. By default, the kit will install itself on "%SYSTEMDRIVE%\Program Files\Windows Kits\8.0\Cryptographic Provider Development Kit" on x86 platforms and "%SYSTEMDRIVE%\Program Files(x86)\ Program Files\Windows Kits\8.0\Cryptographic Provider Development Kit" on 64-bit platforms. We highly recommend that you have your machine fully patched through Microsoft Update before beginning setup.