How to password protect a PDF, step by step

Two kinds of PDF password

You can use either or both. For anything confidential, always set a password to open.

• Password to open (sometimes called the user password): nobody can see the document without it. This is the one that protects confidential content.
• Permissions password (sometimes called the owner password): anyone can open the document, but printing, copying or changes are limited, and only someone with this password can lift the limits.

How to password protect a PDF in PDFZyro

1. 1Open Protect and choose your PDF, or upload it.
2. 2Type a password to open the document.
3. 3If you like, limit what readers can do: allow printing, low-resolution printing only, or no printing; choose which changes are allowed; and turn copying on or off. These limits need a permissions password.
4. 4Save. The file is encrypted with AES-256, the strongest encryption in the PDF standard, and saved as a new version. The unprotected version stays in your private history.
5. 5Download the protected PDF and send it. Share the password separately, for example by text message or phone, not in the same email.

Choosing a strong password

• Length matters most: use at least 12 characters, or a passphrase of four or more random words.
• Don't reuse a password from another account.
• Avoid names, dates and words related to the document.
• Keep the password in a password manager: lost PDF passwords generally can't be recovered.

What PDF passwords don't do

• Permission limits are respected by most PDF readers, but some programs ignore them. They discourage copying; they don't make it impossible. Only a password to open truly protects the content.
• A password protects the file, not what people do after opening it: someone with the password can still share the content.
• Weak passwords can be guessed by software. A long password is what makes the encryption effective.

Removing a password later

If you know the password, you can save an unlocked copy with Unlock PDF, for example to edit, sign or print the document freely. Lifting printing or copying limits also needs the permissions password.

Doing it with the tools you already have

On a Mac, Preview can add a password when you export a PDF: choose File, then Export, and tick the option to encrypt. In Microsoft Word on Windows, when you save a document as PDF, the Options button includes 'Encrypt the document with a password'. Both are fine for a single document; neither lets you limit printing or copying, and Word only works for files you created in Word.

A PDF tool like PDFZyro works on any existing PDF, on any device, and also sets permissions such as no printing or no copying.

Password, redaction or a share link?

• Use a password when the whole document is confidential and you're sending it as an attachment.
• Use redaction when only some information must not be seen, such as account numbers or names, and the rest can be shared. A password doesn't hide anything from someone who has it.
• Use a share link with its own password and an end date when you want to control access after sending, for example to stop access later. PDFZyro share links can also turn downloading off.