You download your e-Aadhaar, PAN card, ITR acknowledgement, or DigiLocker document — open it in Adobe Reader or any PDF viewer — and see a yellow question mark next to the signature with the text "Signature Validity Unknown". This is confusing and often alarming. Is the document fake? Has it been tampered with? The answer is no — and this article explains exactly why it happens and how to fix it.
A digital signature works like a notary seal. For your PDF reader to trust that seal, it must recognise the organisation that issued it. This is done through a Certificate Authority (CA) trust chain. Your PDF reader (Adobe, Foxit, Chrome, etc.) ships with a built-in list of trusted root CAs — mostly commercial ones like DigiCert, GlobalSign, and Comodo.
Indian government documents are signed using certificates issued by Indian government CAs — organisations like:
None of these Indian government CAs are included in the default trust store of Adobe Reader, Foxit, or most other PDF viewers. So when your PDF reader encounters a signature from UIDAI or NIC, it doesn't recognise the issuing authority — and instead of showing a green tick, it shows the yellow "Signature Validity Unknown" warning.
No. "Signature Validity Unknown" does not mean the document is fake or has been modified. It only means your PDF reader doesn't know (and therefore can't confirm) who issued the signing certificate. The document content is intact — the signature is mathematically valid. It's purely a trust configuration issue with your PDF reader, not a problem with the document itself.
This is different from "Signature Invalid" (red X), which would mean the document was modified after signing — a genuine red flag. Validity Unknown simply means the CA is not in the reader's trust list.
Virtually every Indian government-issued digitally signed PDF shows this behaviour by default, including:
Option 1 — Manual: Download the root certificate for each CA (UIDAI, NIC, CBDT, etc.) from the Controller of Certifying Authorities (CCA) website, import it into Adobe Reader's Trusted Identities store, restart Adobe, and repeat for every device you use. This process requires technical knowledge, must be done separately for each CA, and doesn't travel with the document when you share it.
Option 2 — VerifySign.in (recommended): Upload your PDF to VerifySign.in. Our engine validates the signature against a comprehensive store of trusted Indian government root certificates and embeds LTV (Long-Term Validation) data directly into the PDF. The result is a new PDF that shows a permanent green tick in any PDF reader — Adobe, Foxit, Chrome, mobile apps — without the recipient needing to install any certificates. The fix travels with the document.
Instant digital signature verification for any government PDF — free, secure, no software needed.
Go to VerifySign.in →