From PDFArea Software:
PDF Encrypt is a PDF utility that is designed to batch encrypts PDF documents. You may set user password and owner password, you may also set permissions, such as allow printing, allow copying, and extraction. 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 is standalone software; Adobe Acrobat Reader is NOT required. It features support 40-bit RC4 Encryption and 128-bit RC4 encryption, support user password and owner password, prevent printing, copying, extracting, changing, and editing, supports drag and drop PDF files, does not need Adobe Acrobat software, doesn't depend on any print driver, and batch processes PDF documents.