How to Sign a Secured PDF Document?

It’s common to run into a secured PDF that won’t let you sign. Maybe the sender locked it to prevent edits, or the PDF file is password-protected. Either way, you’re stuck with a document that won’t accept your signature.

The fix depends on the type of security in place. Some PDFs only block editing; others are encrypted with a password or certified with a digital seal.

We’ll break down the options so you can sign your PDF document without breaking its integrity.

How to Sign a Secured PDF: Step-by-Step

The quickest way is to remove restrictions (if you have permission) and then add your signature.

Here’s how:

Step 1: Unlock the PDF

Open Unlock PDF and upload the file. If the PDF requires a password, enter it when prompted. Unlocking removes restrictions that stop you from signing.

Step 2: Open Edit PDF

Once unlocked, go to Edit PDF.

Step 3: Add Your Signature

Choose Add Signature, then draw, type, or upload a saved signature image. Place it in the correct field of the document.

Step 4: Save and Download

Click Export to download the signed PDF. You can also send it straight to cloud storage or email it directly.

This method works when you’re dealing with standard editing restrictions.

What If the PDF Is Digitally Certified?

A certified digital signature is a cryptographic seal that validates the document’s authenticity. Once applied, it locks the file so any changes (including adding another signature) will break the certificate.

If that’s the case, here are your options:

• If you’re the signer: Remove the certificate from the original PDF editor and sign again.
• If someone else signed it: Request an unsigned version from the sender.

Trying to delete or override a certified signature usually invalidates the document, so it’s better to start with a fresh copy.

How to Electronically Sign a Non-Editable PDF

Some PDFs don’t allow direct edits because the editing function is restricted, but you can still add your signature as an overlay.

Here’s how: 1. Open Sign PDF. 2. Upload your non-editable PDF. 3. Add your signature on top of the document as an overlay. 4. Save and download the signed file.

This creates a new PDF with your signature, even if the original file couldn’t be edited.

Can You Digitally Sign a Secured PDF?

You can sign a secured PDF, but it depends on the type of security applied. If the file is password-protected, you’ll need the password to open it before you can sign. If the PDF is restricted from editing but still viewable, you can add an electronic signature on top of the document using Smallpdf’s Sign PDF.

Common Issues When Signing Secured PDFs

• “Can’t sign secured PDF” error: Usually means the file has editing restrictions. Use Unlock PDF first.
• Digital seal blocking signatures: The file is certified. Ask the sender for a new copy.
• File locked for printing and copying: These restrictions also block signing. Unlock PDF will solve it.

FAQs

1. How to sign a PDF when it won’t let you?

Upload the file to Smallpdf’s Unlock PDF. Once restrictions are removed, use Edit PDF or Sign PDF to add your signature.

2. How do I remove security from a signed PDF?

If you have the password, use Unlock PDF. If the document has a certified digital signature, request a clean version from the signer.

3. How to digitally sign a PDF without locking?

Use Smallpdf’s Sign PDF. It lets you add a digital signature without applying a cryptographic certificate that locks the file.

4. How do I add a signature to a non-editable PDF?

Upload the file to Sign PDF, place your signature on top, and save it as a new PDF. This works even if the file couldn’t be edited.