How to password-protect a PDF and actually lock a document down

How to put a password on a PDF

Password-protecting a PDF in AtlasDocs takes one field and one click: upload the file, type the password (at least 4 characters) and click "Protect and download". The PDF downloads with the suffix -protected and from then on asks for the password to open, in any reader. It's a real lock: the content is encrypted, unreadable without the password. Everything happens in your browser, and neither the file nor the password goes to any server.

1. Open the Protect PDF with password tool and upload your file (or several; the same password applies to all).
2. Type the password in the "Password (min. 4 characters)" field. The button unlocks only from the fourth character, and there is no confirmation field: type carefully.
3. Click "Protect and download" (with several files, "Protect 3 PDFs"). The PDF comes out with the suffix -protected in its name.
4. Open the downloaded file and test the password before sending it. If you mistyped, there's no way to recover it: protect the original again.

What this tool sets is the open password: whoever doesn't have it reads nothing. It doesn't block printing or copying by someone who has already opened the file; that's what the permissions tool is for, explained below. And keeping the password somewhere safe matters as much as creating it: if it's lost, there is no shortcut to recover the content.

Open password vs. permissions: which do you need?

A PDF can carry two kinds of protection, with different jobs. The open password (also called a user password) locks access: without it, the file won't even open. That's the one for confidential content only certain people should read. Permissions (the so-called edit password, or owner password) let anyone open and read the file, but block actions like printing, copying text or changing the document. In AtlasDocs each has its own tool: Protect PDF with password sets the open password; PDF permissions and restrictions locks the actions you choose. To block printing, copying and editing without requiring a password to open, see how to set PDF permissions.

• Under "Block:", tick "Printing", "Copying text and images" and/or "Editing the content" ("Editing the content" comes ticked by default). At least one action must stay ticked.
• Under "Owner password", create a password of at least 4 characters. It isn't asked for when opening the file: it's the key to lift the restrictions later.
• Click "Apply and download". The file comes out with the suffix -with-permissions and opens without asking for any password; only the locked actions are unavailable.
• Honest note: permissions are honored by common PDF readers, but they aren't as strong a lock as the open password. Content that opens freely can be photographed or copied by other means. For confidentiality, use the open password.

How to choose a password that actually protects

A password only truly protects if it's hard to guess. Go for a long phrase with upper and lower case letters, numbers and a symbol: something you'll remember but no one can deduce from your name or your birthday. The 4-character minimum is what the tool requires, not what an important document deserves. And never send the password in the same email that carries the file: share it through another channel, like a separate message.

What if I want to remove the password later?

You can remove the password later, but only someone who already knows it can. In the Remove PDF password tool, upload the protected file, type the password in the "Current password" field and click "Remove password and download" (with several files, "Remove password from 3 PDFs"). You get a copy with the suffix -unprotected that opens freely. The same tool lifts the restrictions applied by PDF permissions: just enter the owner password. If the password is wrong, the reply is "Incorrect password: could not open the file.", and there is no shortcut for someone who forgot it; that's exactly what keeps the protection secure.

What the tools don't do

• They don't recover a forgotten password or crack someone else's PDF: without the current password, the file stays closed.
• They don't apply an open password and permissions in a single pass: they are two tools, and each produces its own file.
• They don't protect Word, Excel or ZIP files: they are PDF-only tools (AtlasDocs has other tools for Office and archive files).
• They don't swap one password for another in one click: remove the current password and protect again with the new one.

Everything happens in your browser: the PDF and the password you type are never sent to any server. The encryption is done on your own computer.

Keep an unprotected copy somewhere safe. The protected file is the version that circulates; the stored original is your insurance against a forgotten password.