With Nitro Pro, you can apply two different types of security to control who can access your files and what actions they can perform once they receive them: password-based security, and certificate-based security.
Passwords allow you to restrict access and usage of your content to people who have the password used to secure the PDF file. Depending on your needs and the intended audience, you can choose between 40-bit RC4, 128-bit RC4, 128-bit AES, 256-bit AES encryption.
Certificate-based security has many advantages over password-based security: documents can be opened without the need to remember passwords, Digital IDs cannot be shared or copied easily, and a single document can contain different security settings for individual recipients. For example, you may grant one person editing and printing privileges, while another is limited to just viewing the file.