PDFEncrypt

[This is the official version of PDFEncrypt, released by the original author, Ryan Griggs/PDFEncrypt.net] PDFEncrypt is a free, open-source native Windows app that allows you to password protect (encrypt) PDF files for free, without purchasing expensive software. Anyone can open the encrypted files using their existing PDF viewer software, such as Adobe (R) Reader, or the PDF viewers built into most browsers. No additional software is required to decrypt PDF files encrypted with PDFEncrypt. Encrypt (password-protect) your important PDF files with PDFEncrypt for free.