Password Protect PDF — AES-256 Encryption

How to password protect a PDF

1. Drop your PDF file on the box above, or click it to choose the file — or press Load a sample to try it first.
2. Check the settings below the box; the defaults suit most files.
3. Press Convert. Long jobs show a progress bar and can be cancelled; you then see what was made and its real size.
4. Download the .pdf file.

What is kept when you password protect a PDF

• The whole file — pages, text, images, metadata — is encrypted with 256-bit AES, the strongest method in the PDF standard (ISO 32000-2), using your browser’s secure random number generator. It then opens only with your password — in current versions of Acrobat Reader, Chrome, Edge, Firefox, Preview and most phone viewers; readers older than Acrobat X (2010) cannot open AES-256 files at all.
• Before the download is offered, the new file is opened again with pdf.js: it must refuse to open without the password and open with it. The password is never stored or sent anywhere, and it is cleared from the page afterwards.
• Optional restrictions on printing, copying and editing need a second, permissions password. Readers honour them, but they are an agreement rather than a lock — editing software can ignore them. Only the open password protects the content.

Example

Protecting the sample — the facts are measured on the file this produces:

Input

sample.pdf — 3 pages, A4 portrait (440.0 KB)
Password: example-pass · no copying, no editing, no page changes

Output

sample-protected.pdf (440.2 KB)
Encryption: AES-256 (PDF 2.0 security handler, revision 6)
Without the password: does not open
With the password: all 3 pages
Restrictions: no copying, no editing, no page changes

About PDF files

A PDF holds pages that look the same on every device: text with its fonts, vector drawings and images at fixed positions. Pages can be rotated, reordered or copied between files without redrawing them. It opens in any browser, Acrobat Reader, phone and tablet viewers.

Good to know

• A PDF that asks for a password when you open it cannot be processed here; protection is never removed.

Privacy and limits

The file is read and converted by this page in your browser; there is no upload and no account. Nothing inside a PDF is run: there is no PDF JavaScript engine on this page, and links and forms are copied, not followed. Encrypted PDFs are refused rather than unlocked. PDFs may have up to 2,000 pages. Files up to 150 MB are accepted; a file of the wrong type or a damaged file is rejected with the reason.