Security

Use security settings to control who can access your PDF and what actions they can perform. Nitro PDF Pro supports two types of security:

• Password-based security
• Certificate-based security

Password-based security

Use passwords to restrict access to your PDF. Only users with the correct password can open or use the file.

Select one of the following encryption levels:

• 40-bit RC4
• 128-bit RC4
• 128-bit AES
• 256-bit AES (recommended)

Use one of the following password types:

• Open password: Require a password to open the file.
• Permission password: Restrict actions when a user opens the file. For example, prevent users from modifying or printing the document.

Certificate-based security

Use certificate-based security to control access without passwords.

This method has the following advantages:

• Users do not need to remember passwords
• Digital IDs are difficult to copy or share
• You can apply different permissions to different users

For example, you can allow one user to edit and print the document, and allow another user to view the document only.

To view security settings in a file

1. Click File
2. Click Document Properties
3. Click the Security tab

Security profiles

Use security profiles to save and reuse security settings.

Security profiles help you work faster. You do not need to re-enter passwords or add recipients each time you secure a document.

If you use certificate-based security and send files to the same users, security profiles reduce setup time.

To view security profiles

1. On the Protect tab, in the Secure Document group, click Manage Profiles
2. In the Security Profiles dialog, select a profile to view its details

To create a security profile

1. On the Protect tab, in the Secure Document group, click Manage Profiles
2. Click New
3. Enter a name and description
4. In the Secure documents section, select a security type
5. Click Next
6. Configure password or certificate settings
7. Click Finish

To edit a security profile

1. On the Protect tab, in the Secure Document group, click Manage Profiles
2. In the Security Profiles dialog, select a profile
3. Click Edit
4. Update the name and description
5. In the Secure documents section, select a security type
6. Click Next
7. Update the security settings
8. Click Finish

To delete a security profile

1. On the Protect tab, in the Secure Document group, click Manage Profiles
2. In the Security Profiles dialog, select a profile
3. Click Delete
4. Confirm the deletion

FAQs

What happens if you forget the password?
If you forget your Password that you set on a PDF file there is no way of recovering it. So make sure you write it down and keep it in a safe place.

When I open a PDF certain features are greyed out, what does this mean?
When you open a PDF that has had security implemented on it, the author could have set some restrictions such as editing or printing. If you see a greyed out area or options that are not useable then this is what has happened.

Last updated: June 2026