How it works
- Drop the protected PDF in the box above. OpenSigner detects the encryption and asks for the document's password.
- The password is passed to pdf.js running in your tab to decrypt the file in memory. If it is wrong, you are told and can try again.
- Place your signature, date and any text, then finalize.
The password is never sent anywhere or saved. Close the tab and it's gone.
What's different about the signed file
Be aware of two things before you sign an encrypted PDF:
- The pages are rebuilt as images. The library that writes the signed file can't rewrite encrypted PDFs, so OpenSigner renders each page at high resolution and builds a new PDF from those images, with your signature on top. The pages look the same, but text is no longer selectable or searchable. The completion certificate states that the file was rebuilt this way.
- The signed copy isn't password-protected. If the recipient expects a protected file, add a password again with your usual PDF tool after signing.
Unencrypted PDFs are handled differently: their original pages are kept as-is and the signature is added on top.
Owner passwords and restrictions
Some PDFs open without a password but carry restrictions on printing or editing. Only sign documents you are entitled to sign, and if the sender restricted changes, check with them that adding a signature this way is acceptable.