How do I know if a digital signature is valid in Adobe Acrobat?

Open the PDF and right-click the signature. Select 'Validate Signature' from the menu. A dialog box will show the validation status, including who signed and if the certificate is trusted.

If a digital signature shows 'unknown validity', what should I do?

Check the signer's certificate details to see why it's unknown. You might need to add the signer's certificate to your list of trusted identities. Contact the signer to get their certificate or confirm its source.

What is the difference between verifying a signature and managing trusted identities?

Action Purpose Outcome. Verify a Signature To check if a specific signature in a document is valid and who signed it. A report on the validity status of that one signature. Manage Trusted Identities To tell Acrobat which digital certificates you personally trust for future validations. A list of certificates Acrobat will automatically trust when validating signatures.

Audit Signature History in Adobe Acrobat — How-to & AI prompts

AI prompts

2 ways to ask · copy any one

AExecute — “help me do it”Track who signed the supplier contract with [counterparty=GreenLine] and when, then record the…+

Track who signed the supplier contract with [counterparty=GreenLine] and when, then record the signer names and timestamps in the procurement compliance [tracker] for audit purposes.

when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed.

BImprove — “do it better”Make the contract traceable for audit: export the signed agreement with signature timestamps,…+

Make the contract traceable for audit: export the signed agreement with signature timestamps, attach the signer emails and IP log, and add a cover note in the [tracker] explaining any unusual signing sequence before handing it to compliance.

when the reply comes backPush once: ask it to sharpen the weakest part, and to say what it assumed.

How to do it

the tool · the steps · what to avoid

1
Open the PDF document containing the digital signature you want to validate.
2
Locate the signature field or signature panel in the document.
3
Click directly on the digital signature or open the signature panel and select the signature you wish to validate.
4
In the signature details popup, click Signature Properties.
5
In the Signature Properties dialog, click Show Certificate to review certificate details if needed.
6
Close the certificate window, then click Validate Signature in the Signature Properties dialog.
Best practiceIf the signature status shows as 'Unknown' or 'Not Valid', check if the signer's certificate needs to be added to your list of trusted identities.
7
Review the validation result displayed in the Signature Properties dialog.

In the appWith the API

You can view detailed information about the signature's validity and certificate by clicking on the signature and opening Signature Properties.

This runs in the Acrobat app - there is no separate API for this task.

Glossary

words on this page

Digital SignatureAn electronic mark on a document that proves who signed it and that the document has not changed.ExampleA digital signature on your tax return confirms you submitted it and that its contents are unchanged.

CertificateAn electronic file that proves a person's or organization's identity online, like a digital ID card.ExampleYour certificate confirms your identity when you access secure online government services.

Trusted IdentitySomeone whose digital signature certificate you have chosen to trust in your software.ExampleYou add your manager's digital signature certificate as a trusted identity in your document software.

Who does this

3 roles

Contract ManagerLegal AssistantCompliance Officer

FAQ

about this task

Open the PDF and right-click the signature.
Select 'Validate Signature' from the menu.
A dialog box will show the validation status, including who signed and if the certificate is trusted.

A trusted identity is a digital certificate that you have manually marked as reliable in Acrobat. It matters because Acrobat uses these trusted identities to decide if a digital signature is truly valid and from a person or organization you trust. If the signer's certificate is not from a trusted identity, Acrobat cannot fully confirm the signature's authenticity, even if it appears correct.

Check the signer's certificate details to see why it's unknown.
You might need to add the signer's certificate to your list of trusted identities.
Contact the signer to get their certificate or confirm its source.

Adding Long-Term Validation (LTV) information helps a digital signature remain valid over a long time, even if the original signing certificate expires or is revoked. LTV embeds important details like timestamps and revocation status directly into the signed document. This makes the signature self-validating in the future, meaning you won't need external servers to verify its status years later, ensuring its legal standing.

Action	Purpose	Outcome
Verify a Signature	To check if a specific signature in a document is valid and who signed it.	A report on the validity status of that one signature.
Manage Trusted Identities	To tell Acrobat which digital certificates you personally trust for future validations.	A list of certificates Acrobat will automatically trust when validating signatures.

Audit Signature History

When to use it

AI prompts

How to do it

Glossary

The real tasks

Who does this

FAQ

Sources

Adobe help