Guide · Updated September 2026
How to Verify an Electronic Signature
How you verify a signature depends on what kind it is. Certificate-based digital signatures can be validated in a PDF reader. Simple e-signatures are verified through the audit trail and records around them.
Step by step
- Identify the signature type. Open the PDF in Adobe Acrobat Reader. If it shows a signature panel or a banner about signatures, it contains certificate-based signatures. If not, the signature is likely an image or annotation.
- Open the Signatures panel. For certificate-based signatures, open the signature panel in Acrobat Reader to see each signature and its validation status.
- Check the status. Look for whether the document has been modified since signing and whether the signer's certificate is trusted.
- Review the audit trail. For simple e-signatures, open the audit trail or certificate of completion from the e-signature service and check names, emails and timestamps.
- Confirm with the signer if in doubt. If anything looks off, contact the signer through a channel you already trust, not one given in the document.
Why image signatures are hard to verify
A drawn or pasted signature on a PDF is just a picture. Anyone could copy it, so it proves little on its own. The evidence comes from the process: who sent it, to which email, and when it was signed.
Keeping verifiable records
When you send documents with eSignSimple (early access), an audit trail records the signing process so you can show who signed and when.
Frequently asked questions
What does "signature validity unknown" mean in Acrobat?
Usually that Acrobat does not trust the certificate used to sign. It does not necessarily mean the document was altered.
Can I verify a signature added in Preview or Files?
Those add image-based signatures with no certificate, so there is nothing cryptographic to validate. Rely on how the document was exchanged.
How can I tell if a signed PDF was changed?
For certificate-based signatures, the PDF reader reports changes. For other signatures, compare against the copy and document hash recorded by the e-signature service.
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