Methods of securing PDF's

After a bit of research I've come across the following methods of securing PDF files:

• Password security
• Certificate security
• Lifecycle security

All of these except for password 开发者_如何学运维security seem to require software (Adobe) or even servers in the case of lifecycle security - whereas I can add Password security using iTextSharp.

Therefore I'm just looking for the best / accepted methods of providing security of PDF documents. Are there any third party solutions?