Which type of security do you need?

It depends on the protection you need to secure your PDF files.

Examples

Protection level

Actions

You allow only certain people who have the correct password to open a PDF, or copy, print or edit its content.

Require a password to open, copy, or print its contents.

Choose Security > Encryption.

  1. Open Password. Only people with the correct password can open and view the document.

  2. Permission Password. You don't need a password to open the document, but you need the correct permissions password to change the restricted functions.

  3. Interactive Password. You can secure a PDF file with both types of passwords and further choose which content to encrypt and which action to restrict. The PDF secured with both types of passwords can be opened with either one. However, only the permissions password allows users to change the restricted functions.

See Securing PDFs with passwords.

You want to allow specified people to view the PDF and apply different security schemes to recipients.

Only the people you specify can view and open the PDF encrypted with certificates.

Choose Security > Encryption > Interactive Certificate. Alternatively, you can open the Document Properties dialog box and choose Security > Security Method > Certificate Security. To specify recipients, you must import the certificates from intended recipients into your list of trusted identities.

See Securing PDFs with certificates.

You want recipients to know that you have already approved the PDF content.

Sign and certify the PDF with a digital ID to add digital signatures.

Choose Security > Sign/Certify > Sign/Certify. Select Certify Document to add your digital ID. Then you can specify which action can be done by recipients. To perform signing/certifying, you need a digital ID, which can be either an existing one or a Self-Signed Digital ID.

See Signing PDFs.

You want to send the PDF as email attachment without having to encrypt all contents.

Attach a PDF to an email.

Choose Security > Secure Delivery. You can send a protected PDF as email attachment.

 

Password-/certificate-based security

You can use password-based security and certificate-based security to control who can access the files and which function they can use once the protected file is opened. If you use passwords to secure your PDF file, only the people who have the password can view or make changes to your PDF file. If you use certificate-based security, only the people you specify can view the PDF, and passwords are not needed to open documents. 

 

Password-based security

You can use passwords to restrict access to a PDF document or certain functions after the PDF is opened. Then, you can specify a desired encryption type, a PDF version, and other settings for the intended recipients. There are two types of password-based security:

  • Document open password. Only people having the correct open password can open and view the PDF file.

  • Permissions password. Using a permissions password, you can restrict certain functionalities, including printing, editing and copying. Though the permissions password doesn't restrict opening the PDF, you need to enter the correct password to change the security settings.

 

Certificate-based security

Using a certificate to secure a PDF, you can ensure that only the intended recipients can view a PDF. Furthermore, the digital signature serving as a certificate assures recipients that you are the person who distributed the document.

When encrypting a PDF with a certificate, you can specify the documents to encrypt, the level of encryption, the recipients allowed to open the document, and further specify different security settings for individual recipients. For instance, you may allow one person to perform commenting, filling forms, while others can do anything except for extracting pages.

View the security method applied to a PDF

In the Document Properties dialog box you can view which type of security method is currently employed and choose a method for the document. You can also choose No Security from the Security Method menu to directly remove existing restrictions.

  1. Open a PDF file. If the document is encrypted with password-based security, you have to type in the document open password to open and view the PDF.

  2. Do one of the following to open the Document Properties dialog box:

    • Choose Security > Encryption > Security Properties.

    • Press Command + D on your keyboard.

    • Choose File > Properties > Security tab.

  1. On the Security tab, the Security Method menu shows the security method applied to the document:

    • Click Details... for more security information regarding encryption level and encrypted content.

    • Click Settings... to edit security settings. If the document is secured with a permissions password, you have to type in the correct password to unlock restricted functions.

    • You can remove the existing encryption by selecting No Security from the Security Method drop-down menu. If the PDF document has already been secured by a permissions password, you will be prompted to enter the correct permissions password before you can remove permissions settings.


The Document Properties dialog box where you can view and edit the security method applied to the file.



Enter the correct permissions password to remove security settings of the document encrypted with permissions password.

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