PDF Encrypt is a quick and easy-to-use PDF utility that is designed to batch encrypt PDF documents. It Supports 40-bit RC4, 128-bit RC4, 128-bit AES and 256-bit AES Encryption.
You may set password and permissions (such as disallow printing, disallow copying etc.) to protect your PDF documents.
If you encrypt a PDF document by setting the user password, no one can open the PDF document except he knows the correct password.
PDF Encrypt doesn’t depend on any print driver so it will NOT install any print driver on your computer.
Several other good free alternatives. The only advantage this may have is 256 bit encryption.
http://alternativeto.net/tag/encrypt-pdf/?license=free