Hi ,
Protection of PDF using VBA is possible in 2 ways
1. We can protect the existing PDF which is already there
2. We can create PDF using excel and then Protect
You need adobe professional version to be installed. You have to create SecuritySettings Object, ConversionSettings Object and PDFMakerApp object.
Using the 3 object linked to each other we can lock the pdf. If you would like to know more details please email me
Thanks and Regards
Raj Mohan