Securing PDFs with passwords

Open the PDF in Acrobat. From the global bar in the upper left, select All tools > Protect a PDF > Protect with password. 

If you receive a prompt, select Yes to change the security.

Choose Editing, and then type and retype your password. Your password must be at least six characters long. The password strength is displayed next to your password to indicate whether the chosen password is weak, medium, or strong.

Select Apply. Acrobat displays a confirmation message that the file was successfully protected using the password.

Open the PDF in Acrobat. From the global bar in the upper-left, select All tools > Protect a PDF. From the Protect a PDF toolset in the left pane, select Encrypt with Password. 

If you receive a prompt, click Yes to change the security.

Select Restrict editing and printing of the document.

All Adobe products enforce the restrictions set by the permissions password. However, if third-party products don’t support these settings, document recipients can bypass some or all your restrictions.

Type the password in the corresponding field. Your password must be at least six characters long. For each keystroke, the password strength meter evaluates your password and indicates the password strength.

Select what the user can print from the Printing allowed menu:

Prevents users from printing the document.

Lets users print at no higher than 150‑dpi resolution. Printing may be slower because each page is printed as a bitmap image. This option is available only if the Compatibility option is set to Acrobat 5 (PDF 1.4) or later.

Lets users print at any resolution, directing high-quality vector output to Adobe PostScript and other printers that support advanced high-quality printing features.

Select what the user can change from the Changes allowed menu:

Prevents users from modifying the documents listed in the Changes Allowed menu, such as filling in form fields and adding comments.

Lets users insert, delete, and rotate pages, and create bookmarks and thumbnails. This option is only available for high (128‑bit RC4 or AES) encryption.

Lets users fill in forms and add digital signatures. This option doesn’t allow them to add comments or create form fields. This option is only available for high (128‑bit RC4 or AES) encryption.

Lets users add comments and digital signatures, and fill in forms. This option doesn’t allow users to move page objects or create form fields.

Lets users edit the document, create and fill in form fields, and add comments and digital signatures.

Choose any of the following options:

Lets users select and copy the contents of a PDF.

Lets visually impaired users read the document with screen readers, but doesn’t allow users to copy or extract the document’s contents. This option is available only for high (128‑bit RC4 or AES) encryption.

Select an Acrobat version from the Compatibility menu. Choose a version equal to or lower than the recipients’ Acrobat or Acrobat Reader version. The Compatibility option you choose determines the type of encryption used. It's important to choose a version compatible with the recipient's version of Acrobat or Acrobat Reader. For example, Acrobat 7 can’t open a PDF encrypted for Acrobat X and later.

• Acrobat 6.0 And Later (PDF 1.5) encrypts the document using 128-bit RC4.
• Acrobat 7.0 And Later (PDF 1.6) encrypts the document using the AES encryption algorithm with a 128-bit key size.
• Acrobat X And Later (PDF 1.7) encrypts the document using 256-bit AES. To apply 256-bit AES encryption to documents created in Acrobat 8 and 9, select Acrobat X And Later.

Select what you want to encrypt:

Encrypts the document and the document metadata. If this option is selected, search engines can’t access the document metadata.

Encrypts the contents of a document but still allows search engines access to the document metadata.

Requires a password to open file attachments. Users can open the document without a password. Use this option to create security envelopes.

Select OK. Retype the appropriate password in the box at the prompt to confirm the password and select OK.

Open the PDF, then select All tools > Protect a PDF > Set security properties.

Your options vary depending on the type of password security attached to the document:

• If the document had only a Document Open password, deselect the Require a password to open the document option, and then select OK to remove it from the document.
• If the document had a Permissions password, deselect the Restrict editing and printing of the document option. Type the password in the Enter Password box when prompted, and then select OK. Select OK again to confirm the action.