Signing a VMWare Virtual Machine
Yes, you can absolutely sign a VMware VM, and ironically, the exact method you used in your blog post to trick VirtualBox into accepting a signed appliance is actually VMware's official, native standard for signing VMs.
.ova (Open Virtual Appliance) format is inherently a tar archive containing an OVF descriptor (.ovf), disk images (.vmdk), and a manifest file (.mf), the process for VMware relies completely on the same VMware OVF Tool (ovftool.exe) and a PEM-formatted certificate that you previously set up..pem key ready to go, here is how you sign it natively for VMware, along with how to fix the timestamp and manifest warnings you ran into last time:--shaAlgorithm flag explicitly set to SHA256. Most modern hypervisors (including VMware Workstation/vSphere) will flag or reject SHA1 as cryptographically broken. [1]ovftool --privateKey=MyCert.pem --shaAlgorithm=SHA256 source_vm.ova signed_vm.ova
.vmdk disk file. [1]Warning: No supported manifest(sha1, sha256, sha512) entry found for: 'filename-disk001.vmdk'
.mf) file that doesn't map hashes in a way the OVF standard expects.- The Fix: If you export the base VM directly from VMware Workstation (instead of VirtualBox), its OVF/OVA exporter writes a mathematically clean, natively mapped manifest file automatically. Running
ovftoolagainst a VMware-exported OVA will completely eliminate this warning.
ovftool simply signs the file locally using your key. When your Sectigo certificate expires, the VM will show up as untrusted. [1, 2]ovftool command using the --tsa flag. This injects a cryptographically verified time token into the OVF signature, ensuring the VM remains trusted forever as long as it was signed while the certificate was valid.--tsa parameter to your command:ovftool --privateKey=MyCert.pem --shaAlgorithm=SHA256 --tsa=http://sectigo.com source_vm.ova signed_vm.ova
signed_vm.ova into VMware Workstation or vSphere:- The hypervisor intercepts the package and checks the embedded
.certfile against the OS trusted root store. - It will display a clear "Publisher: Validated/Trusted" banner along with your certificate details.
- If anyone tampers with a single byte of the underlying BSD disk or OVF configuration file, the manifest hash verification will break instantly, and VMware will refuse to boot or import the machine, protecting your "known good" release.
