How to Protect a Fillable PDF Using Password Security and Digital Signatures

Question

I am using Acrobat DC. I have a client who only has Reader. She is requesting that I send her a fillable PDF that is locked. She needs to be able to unlock the PDF herself, edit the fillable fields, re-lock it, and send it out to her clients.

I tried "restrict editing", and it does not stop the ability to edit the fillable fields.

I tried creating a password protection, but when I unlock the document it only allows me to make changes under the Edit tool, not the fillable fields. Also it does not give me an option to use the password to use the Prepare Form tool. It just says that I cannot use Prepare Form because of the security settings.

I also thought of locking each field in the properties window, but then she would not be able to unlock or edit them.

I hope this makes sense. TIA for your help!

BaniVerma · Accepted Answer

Hi all,How can I protect a completed fillable PDF?Acrobat provides different document protection features depending on your workflow.Password security helps control who can open a PDF or perform actions such as editing, printing, copying content, or changing security settings.Digital signatures help verify the signer's identity and indicate whether a document has been modified after it has been signed.These features serve different purposes and can be used together when your workflow requires both document protection and document integrity verification.Password SecurityDigital SignaturesControls access and permissionsVerifies document authenticity and integrityCan restrict editing, printing, copying, and security changesIndicates whether a document has changed after it was digitally signedUses Document Open and Permissions passwordsUses a certificate-based Digital IDReferenceshttps://helpx.adobe.com/acrobat/desktop/protect-documents/protect-with-passwords/add-passwords-to-pdfs.htmlhttps://helpx.adobe.com/acrobat/desktop/e-sign-documents/fill-sign-documents/add-digital-sign.htmlhttps://helpx.adobe.com/sign/config/digital-signatures/overview.htmlHow do passwords and permissions protect a PDF?Acrobat supports two types of password security.A Document Open Password requires a password before the PDF can be opened.A Permissions Password allows the document owner to restrict editing, printing, copying content, or changing security settings.Users who know the permissions password can modify or remove those restrictions.Referenceshttps://helpx.adobe.com/acrobat/desktop/protect-documents/protect-with-passwords/add-passwords-to-pdfs.htmlhttps://helpx.adobe.com/acrobat/desktop/protect-documents/protect-with-passwords/remove-passwords-from-pdfs.htmlCan a recipient unlock, edit, and restore the original password protection?No. Acrobat doesn't provide a workflow that allows a recipient using Acrobat Reader to temporarily remove password protection, edit the PDF, and then restore the original security settings.If a PDF is protected with a Permissions Password, modifying the document or its security settings requires that password. If you don't have it, contact the document owner.What if I forgot the password myself?Acrobat doesn't offer a password recovery option. If you lose or forget a PDF's password, there's no built-in way to retrieve it or remove the restriction without it.If this happens:Check whether you have an earlier, unprotected copy saved elsewhere (email, cloud storage).Check a password manager or browser, in case the password was saved when you last opened the file.If someone else created the PDF, ask them for the password.Once you have the password, you can remove it: Tools > Protect > Encrypt > Remove Security.Referencehttps://helpx.adobe.com/acrobat/desktop/protect-documents/protect-with-passwords/remove-passwords-from-pdfs.htmlWhich document protection method should I choose?Choose password security when you want to control access to a PDF or restrict editing and printing. Choose digital signatures when recipients need to verify document authenticity and whether the document has been modified after signing.Depending on your workflow, password security and digital signatures can be used together to provide both document protection and document integrity verification.Password protection matters beyond access control — it helps prevent unauthorized distribution of sensitive contracts, financial reports, and employee records, and can support compliance with industry regulations.Referenceshttps://helpx.adobe.com/acrobat/desktop/protect-documents/protect-with-passwords/add-passwords-to-pdfs.htmlhttps://helpx.adobe.com/acrobat/desktop/e-sign-documents/fill-sign-documents/add-digital-sign.htmlhttps://experienceleague.adobe.com/en/docs/document-cloud-learn/acrobat-learning/get-started/tools/password-protectThanks,^BS

Test Screen Name · Answer

I think it's important to identify what it is that you are protecting against. Often this has not been explored in detail, there's just a feeling that it isn't secure. Here are some possibilities, there are many more.

1. Accidentally overwriting a shared original form. Solution: protect the original file with system security, nothing to do with PDF.

2. Opportunistic price or order fraud (changing the prices on a quote for example). NOTHING can protect properly against this. If your company is vulnerable to this, then it's worth someone's trouble - if the PDF is too hard to edit - to type up a new fake. If a company is open to this fraud, it has a fault in procedures; it needs to be someone's job to check the numbers against records.

3. Contract fraud: changing the terms of a contract before returning it signed. The solution here does exist, digital signatures. They can be used to prove that the client changed the contract - needs expert advice to set up something legally binding. Staff may need to be trained to check signatures (every time potentially, and NOT by just looking at the marks on the page, which are easily faked).

4. User convenience: if the user doesn't need to change the form any more, why confuse them by inviting them to fill it? This can be handled by setting fields read only but beware: don't do this just because the form is saved. Form designers forget that forms often have to be saved when half filled, to return later (after lunch, a meeting, going away to look up stuff for the form, or a crisis).

5. Protecting secrets inside the scripts of the form, for example passwords or internal pricing, or protecting the work done in writing the scripts from competitors. You can't protect this, don't even try. Be sure you don't need secrets in the form, by design.

Password Security	Digital Signatures
Controls access and permissions	Verifies document authenticity and integrity
Can restrict editing, printing, copying, and security changes	Indicates whether a document has changed after it was digitally signed
Uses Document Open and Permissions passwords	Uses a certificate-based Digital ID

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