In the [Lviv hackathon](/Meetups/2018-Lviv) the we agreed on the following things:

* OpenVPN 2.5 Windows installer should be MSI-based

* We won't provide NSIS installers for 2.5 unless there are major issues in the MSI

* The installer should include OpenVPN, OpenVPNService, tap-windows6 etc. each as separate MSI feature

* People who want to install just tap-windows6 can disable the OpenVPN features

* We should not try to embed MSI installers into MSI installers due to lack of good documentation

* Each installation architecture/target will get its own MSI installer

* We should bundle all the MSI installer into a thin wrapper executable, such as a self-extracting p7zip archive with a script hook that detect which MSI to launch

* The individual MSI files should also be made available for more technical users as well as system administrators

* The custom action DLL used in the tap-windows6 MSI installation logic could be included in openvpn.git, so that openvpn-build could easily build and sign it, just as is done with openvpn.exe and openvpnserv.exe. Having it in tap-windows6 repository would make signing that DLL slightly more problematic, as we don't really sign anything with the tap-windows6 buildsystem anymore.

* The MSI (WiX) code can be placed into a subdirectory in openvpn-build Git repository alongside "generic", "msvc" and "windows-nsis". The MSI should consume the artefacts that the openvpn-build cross-compile process produces.

* The documentation and instructions on how to deploy, transform, or parameterize MSI packages should be published on Wiki and/or in the openvpn-build readme.

* The documentation and instructions for developers on components, their functions and relationship should be published on Wiki and/or in the openvpn-build readme.

There are several "targets" for the installer. We not only have the architecture split (i386, x64, amd64), but also different types of kernel-mode signatures for tap-windows6:

|**Operating system**|**KM signature** |**i386**|**x64**|**arm64**|

|-|-|-|-|-|

|Windows 7/8 |Cross-signed | X | X | |

|Windows 10 |Attestation-signed![1]| X | X | X |

|Windows Server 2012r2 |Cross-signed | | X | |

|Windows Server 2016 |WHQL-certified | | X | |

|Windows Server 2019 |WHQL-certified | | X | |

So we have the following architecture-signature combinations for tap-windows6:

1. i386/x64 cross-signed

1. i386/x64/arm64 attestation signed

1. x64 WHQL certified

The user-mode signatures for openvpn.exe, openvpnserv.exe etc. can be created with standard, non-EV authenticode keys on all platforms.

[1] The requirement for attestation signatures in kernel-mode code came into Windows 10 quite early. It is not know if really old Windows 10 version can load attestation-signed drivers, but that seems likely. Even if they don't we may not want to support those