Acrobat 7.0 And Later (PDF 1.6) encrypts the document using the AES encryption algorithm with a 128-bit key size.Acrobat 6.0 And Later (PDF 1.5) encrypts the document using 128-bit RC4.

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

Select an Acrobat version from the Compatibility drop-down menu. For each keystroke, the password strength meter evaluates your password and indicates the password strength. Select Require a Password to Open the Document, then type the password in the corresponding field. If you receive a prompt, click Yes to change the security. Open the PDF and choose Tools > Protect > Encrypt > Encrypt with Password. Please refer to Microsoft Office support website for more details. Each time you open the document, you will be prompted to enter your password to access its contents. Microsoft Word will now indicate the document is protected. Click Encrypt with Password.Įnter the password again to confirm it and click OK. Click the File menu, select the Info tab, and then select the Protect Document button. The procedure is standard for most Office applications, so for this example, we will use Microsoft Word 2016.įirst, open the Office document you would like to protect.

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