[[TOC(inline, depth=1)]] = Introduction = Generic build instructions for tap-windows6 [https://github.com/OpenVPN/tap-windows6/blob/master/README.rst are available] in it's Git repo. This page contains additional information that is more generic and not really suitable for inclusion in the main documentation. = Generic requirements = Getting the [https://msdn.microsoft.com/en-us/library/windows/hardware/ff686697%28v=vs.85%29.aspx Authenticode signatures] right so that all Windows versions detect them can be quite tricky. This seems to be particularly true for kernel-mode driver packages. The Authenticode signatures have a few requirements: 1. The Certificate path needs to be complete. This can be achieved by including [https://msdn.microsoft.com/en-us/library/windows/hardware/dn170454%28v=vs.85%29.aspx cross-certificate of your CA] (e.g. Digicert) in the signed files. At least for Digicert non-EV and EV code-signing certificates have different CAs. 1. The signature needs to be timestamped, or the driver will stop functioning when the code-signing certificate expires. It is not clear if signtool's digest algorithm (/fd SHA|SHA256) affects the acceptability of the signature in Windows 7 and beyond, or if the only important thing is the hash algorithm of the actual certificate. Cross-signing is possible for Windows 7/8/8.1/Server 2012r2 as long as the certification authority's cross-certificate is valid. Beyond that point an actual Microsoft signature is required in all drivers. Windows 10 already requires these Microsoft signatures - they're called [https://docs.microsoft.com/en-us/windows-hardware/drivers/dashboard/attestation-signing-a-kernel-driver-for-public-release attestation signatures] in MS jargon. These signatures can be created in [https://developer.microsoft.com/en-us/windows Windows Dev Center] once you've cleared all the bureaucratic obstacles like signing in to development programs and registering your EV hardware token with your account. Here are the general prequisites for building and signing, regardless of signature type: * On build computer * [https://github.com/OpenVPN/tap-windows6 tap-windows6] source directory is up-to-date * [https://docs.microsoft.com/en-us/windows-hardware/drivers/develop/using-the-enterprise-wdk Enterprise Windows Drive Kit] ISO image is installed and mounted as a system drive * tap-windows6 build system is configured properly (file paths etc.) * A user- or kernel mode authenticode certificate is present for signing the tap-windows6 ''installer'' * On signing computer * An EV token is visible in the Windows Certificate Store * [https://github.com/mattock/sign-tap6 Sign-Tap6] source directory is up-to-date * A correct cross-certificate from your CA is installed into the sign-tap6 directory * Sign-Tap6 is configured properly * Your workstation * You are able to transfer files (e.g. via SSH) from and to the build and signing computers In the documentation below it is assumed that all Windows commands are executed from within a Powershell session. = Building for Windows Vista = **NOTE:** It is generally a bad idea to support Windows Vista. But if you must, please look [wiki:SigningForWindowsVista here]. = Building and signing for Windows 7/8/8.1/Server 2012r2 = Any relatively recent Windows 7 installation supports SHA2 Authenticode signatures. This means that the laborious and fragile [wiki:SigningForWindowsVista dual-signature process] can be avoided. You only need the EV SHA2 kernel-mode code-signing certificate, which probably comes in the form of a dongle that integrates with Windows certificate store. The tap-windows6 ''installer'' may optionally signed with a different, non-EV SHA2 code-signing certificate. The building and signing process is as follows '''On build computer''' {{{ $ cd tap-windows6 $ python buildtap.py -c -b }}} '''On workstation''' Copy the tap6.tar.gz from the build computer to the signing computer. '''On signing computer''' {{{ $ cd sign-tap6 $ tar -zxf tap6.tar.gz $ Sign-Tap6.ps1 -SourceDir tap6 -Force $ Move-Item tap6 tap6-signed $ tar -zcf tap6-signed.tar.gz tap6-signed }}} The EV dongle will probably prompt you twice per architecture (x86, x64, arm64) as it signs the catalog file and tapinstall.exe for each. Note that the -Force switch ''is required'' or the file hashes in the .cat files will be incorrect and the driver will not install. '''On workstation''' Copy tap6-signed.tar.gz from signing computer to the build computer for packaging. '''On build computer''' = Building and signing for Windows 10 = On top of the generic requirements listed above there are a few extra requirements when doing attestation signing: * You need to register your EV dongle with your organization's account in the Windows Dev Center ([https://developer.microsoft.com/en-us/dashboard/account/managecertificates direct link]). * INF file syntax needs to be valid, as MS backend servers will check it at submission time. Use the latest version of !InfVerif (see footer in Hardware Dev Center) to validate the syntax before submission. The building and signing process is as follows '''On build computer''' {{{ $ cd tap-windows6 $ python buildtap.py -c -b }}} '''On workstation''' Copy the tap6.tar.gz from the build computer to the signing computer. '''On signing computer''' {{{ $ cd sign-tap6 $ tar -zxf tap6.tar.gz }}} The next steps are * Generate a cabinet file as described [https://docs.microsoft.com/en-us/windows-hardware/drivers/dashboard/attestation-signing-a-kernel-driver-for-public-release here]. * ''You have to'' put the driver files into one or more directories in the cabinet file as shown in the example diagram [https://docs.microsoft.com/en-us/windows-hardware/drivers/dashboard/attestation-signing-a-kernel-driver-for-public-release here]. If you don't, cabinet file verification will fail. * Sign the cabinet file with the EV dongle using signtool.exe * Submit the cabinet file to Windows Dev Center to obtain an attestation signature = Useful commands = == Installing certificates == Installing a PFX file to the Currentuser certificate store using Powershell: {{{ Import-PfxCertificate –FilePath cert:\CurrentUser\My -Password (ConvertTo-SecureString -String -Force –AsPlainText) }}} If you're not accustomed to Powershell you can just use ''mmc.exe'' and the certificate snap-ins to install the certificate. == Querying the certificate store == To list all certificates in ''Currentuser\My'' store using Powershell: {{{ Get-ChildItem cert:\CurrentUser\My }}} Or alternatively: {{{ Set-Location cert:\CurrentUser\My dir }}} The ''dir'' command is just an alias for ''Get-!ChildItem'' == Creating catalog files with inf2cat == To create a catalog file for a 32-bit driver: {{{ Inf2Cat.exe /driver: /os:Vista_x86,Server2008_X86,7_X86 }}} To create a catalog file for a 64-bit driver: {{{ Inf2Cat.exe /driver: /os:Vista_X64,Server2008_X64,Server2008R2_X64,7_X64 }}} Example: {{{ Inf2Cat.exe /driver:C:\Users\John\tap6\amd64 /os:Vista_X64,Server2008_X64,Server2008R2_X64,7_X64 }}} '''NOTE:''' According to Microsoft Inf2Cat requires a full path to the driver directory. == Signing files with signtool.exe == '''NOTE:''' signtool seems to expect absoluete paths to certificate files. Below only the filenames are given for clarity. Sign a file using a (non-EV) certificate stored in a pfx file. Note that this process is not suitable for EV certificates, which are probably all stored in some sort of dongle and thus only visible through the Windows Certificate Store: {{{ signtool.exe sign /v /ac /t /f /p }}} Sign a driver with the "best" certificate found from the certificate store. This should work if there is only code-signing certificate in the store: {{{ signtool.exe sign /v /ac /t /a }}} Sign a driver using a certificate under ''Currentuser\My'', selecting the right certificate based on a substring of the certificate's subjectname: {{{ signtool.exe sign /v /ac /t /s My /n }}} Example of adding two signatures and timestamps. This requires a relatively recent signtool.exe (e.g. from Windows Kit 10): {{{ # Create primary (SHA1) signature (certificate in a pfx file) signtool.exe sign /v /f digicert-sha1.pfx /p /ac digicert-assured-id.crt /t http://timestamp.digicert.com /fd SHA1 tap6/amd64/tap0901.cat # Add secondary (SHA2) signature (certificate in the certificate store) signtool.exe sign /v /s My /n OpenVPN /ac digicert-high-assurance-ev.crt /as /fd SHA256 tap6/amd64/tap0901.cat signtool.exe timestamp /tr http://timestamp.digicert.com /td SHA256 /tp 1 tap6/amd64/tap0901.cat }}} Signing a file (e.g. the installer) directly with Signtool using a certificate from local PFX file. {{{ signtool.exe sign /v /ac digicert-assured-id.crt /f digicert-user-mode-2019.pfx /p password /t http://timestamp.digicert.com tap-windows-9.22.1-I601.exe }}} == Validating signatures == Verifying the Authenticode signature of a file using Powershell: {{{ Get-AuthenticodeSignature }}} Note that even if the above command says that the file's certificate is valid, there is absolutely no guarantee that various Windows versions will accept it. It is unclear whether the Cmdlet checks the entire certificate path or not: it does hang for long periods of time occasionally doing ''something''. Using signtool.exe to verify a driver's signature probably gives more reliable results than the Get-!AuthenticodeSignature Cmdlet: {{{ signtool.exe verify /v /kp /c .cat .sys }}} Signatures can also be validated by looking at "File properties" of the ''tap0901.cat'' file. The publisher should show up correctly in some places (not necessarily all), there should be a timestamp counter-certificate, and an unbroken certification path should be present. = External links = '''General information''' * [http://www.osr.com/blog/2015/07/24/questions-answers-windows-10-driver-signing/ Questions and Answers: Windows 10 Driver Signing] * [https://docs.microsoft.com/en-us/windows-hardware/drivers/dashboard/attestation-signing-a-kernel-driver-for-public-release Attestation signing a kernel driver for public release] * [http://www.davidegrayson.com/signing/ Practical Windows Code and Driver Signing] * [https://msdn.microsoft.com/en-us/library/windows/hardware/ff686697%28v=vs.85%29.aspx Authenticode Digital Signatures] * [https://msdn.microsoft.com/en-us/library/windows/hardware/dn170454%28v=vs.85%29.aspx Cross-Certificates for Kernel Mode Code Signing] * [https://bugzilla.mozilla.org/show_bug.cgi?id=1079858 Bug 1079858 - Deal with deprecation of SHA1 (SHA-1) Authenticode signatures for Windows signing] (from Mozilla.org) '''Practical guides''' * [https://technet.microsoft.com/en-us/library/dd919238%28v=ws.10%29.aspx Steps for Signing a Device Driver Package] * [https://github.com/pbatard/libwdi/wiki/Signed-Driver-Walkthrough Signed Driver Walkthrough] (from libwdi project) * [http://www.microsoft.com/whdc/driver/install/drvsign/kmcs-walkthrough.mspx Microsoft's Kernel-Mode Code Signing Walkthrough] (in doc format) '''References''' * [https://msdn.microsoft.com/en-us/library/windows/hardware/ff553618%28v=vs.85%29.aspx Inf2Cat] * [https://msdn.microsoft.com/en-us/library/windows/desktop/aa387764%28v=vs.85%29.aspx Signtool] * [https://technet.microsoft.com/en-us/library/hh849805.aspx Get-AuthenticodeSignature] * [https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.security/set-authenticodesignature?view=powershell-6 Set-AuthenticodeSignature] * [https://technet.microsoft.com/en-us/library/hh848625.aspx Import-PfxCertificate]