How to Verify a Digitally Signed PDF Received from Someone Else
A signed PDF lands in your inbox with a neat signature block on the last page. That picture proves nothing by itself. Real verification takes one minute in Adobe Reader — and it separates a genuine, untouched document from a edited file with a copied signature image.
✍️ Technical Anshu🪟 Windows 10 / 11⏱️ 7 minute read
🎥 Watch the full video — see how real DSC signatures are created, so you know what a genuine one looks like
Anyone can paste a signature image into a PDF. What they cannot fake is a cryptographic signature that validates: correct certificate chain, document unchanged since signing, signer who they claim to be. This guide verifies a received PDF in Adobe Reader the proper way — signature panel, certificate details, and the three checks that actually matter.
A properly verified signature — what you want to see
✅ Signature valid — chain verified to a trusted authorityValid
📄 Document not modified since this signature was appliedUnchanged
👤 Signer identity — name and issuing Certifying Authority shownConfirmed
☝️ All three green points together mean genuine. Any one failing deserves a question back to the sender
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Open It in a Real PDF Reader — Not the Browser
Browser PDF viewers show the page but cannot properly validate signatures.
Save the attachment to your PC first
Open it in Adobe Reader (free) — its signature validation is the reference standard
Look for the signature status bar at the top of the document and the Signatures panel on the left
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Check 1 — The Validity Status
Read the exact words; unknown and invalid are very different findings.
Valid (green tick): the signature verified completely — proceed to the identity check
Validity unknown (question mark): the document is reported unchanged, but your reader does not yet trust the issuing chain — for Indian DSCs, update the trust list (Trust Manager → Update Now) and re-check before judging the document
Invalid (red cross): the document changed after signing or the signature is damaged — do not accept it at face value; ask the sender for the original signed file
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Check 2 — The Document Is Unchanged
This is the heart of a digital signature.
In the Signatures panel, expand the signature entry and read its status lines
Confirm it states the document has not been modified since the signature was applied
If multiple signatures exist, check each one — a later signer signs the document including whatever state it was in at their turn
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Check 3 — The Certificate Belongs to the Right Person
A valid signature from the wrong person is still the wrong signature.
Right-click the signature → Show Signature Properties → Show Signer's Certificate
Read the signer's name — it must be the person who was supposed to sign (for company documents, the authorised signatory)
Read the issuing authority — a licensed Certifying Authority under CCA India for Indian DSCs, not an unknown self-created name
Note the signing time and certificate validity dates — the signing should fall inside the certificate's valid period
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Red Flags That Mean Stop and Ask
Any one of these justifies returning the document.
The signature is only a picture — no entry in the Signatures panel at all
Status shows invalid, or the document-modified warning appears
The certificate is issued to a different name than the person who claims to have signed
The sender resists sending the original signed file and offers only a printout, scan or re-saved copy
🔴 Honest note: verification proves the document is authentic and unchanged — it does not prove the contents are true or the deal is fair. Read what you are accepting; the green tick vouches for the signature, not for the bargain.
🎥 Watch How Genuine DSC Signatures Are Made
The full signing video shows the real process behind a verifiable signature — token, certificate and PIN, no shortcuts.
The PDF shows a signature image but nothing in the Signatures panel. Is it signed?
No — not digitally. A pasted image has no cryptographic data behind it and can be copied into any document. Treat the file as unsigned and ask for the properly signed version.
Validity shows unknown for a government-issued document. Should I reject it?
Not on that alone. Unknown usually means your Reader has not updated its trust list for the Indian CA chain. Update the AATL in Trust Manager, reopen the file, and then judge. If it still cannot verify and the sender cannot explain, escalate.
Can I verify a signed PDF on my phone?
Mobile readers show limited signature information and often cannot validate chains fully. For anything that matters — contracts, certificates, official letters — verify once on a PC in Adobe Reader before acting on the document.
This guide is based on the Technical Anshu bulk PDF signing with DSC video • Stuck on any step? Ask in the video comments — help is available there 🙏