While browsing the VMTN forums the other day, I just learned that you can sign your own OVF files using VMware'sovftool. To sign your OVF files, you will need the .ovf, .vmdk files and an X.509 certificate. Though not mandatory, you should also have a manifest file that includes a ...
[--mode machine|machineandchildren|all] [--options link|keepallmacs|keepnatmacs| keepdisknames] [--name <name>] [--groups <group>, ...] [--basefolder ] [--uuid <uuid>] [--register] import <ovfname/ovaname> [--dry-run|-n] [--options keepallmacs|keepnatmacs|importtovdi] [mor...