Validate PDF Signature
Verify who signed a PDF, when, and whether it is intact.
Overview
The Validate Signature tool inspects the digital signatures embedded in a PDF and reports, for each one, the signer (from the certificate), the signing time, any stated reason or location, and — most importantly — whether the signature is cryptographically intact: that is, whether the bytes the signature covers have been altered since it was applied. Validation is performed entirely on our servers in managed code (no third-party service); your file is deleted immediately after processing.
How to Use
- Navigate to Validate Signature from the Security & Optimization menu.
- Upload your file using drag-and-drop, Browse Files, or cloud storage (Dropbox / Google Drive).
- Click Validate Signatures.
- Review the per-signature results shown on the page.
Reading the Results
| Field | Meaning |
|---|---|
| Intact | The signature verifies and the content it covers has not changed since signing. |
| Modified or invalid | The signature could not be verified — the covered content may have been altered. |
| Signer / Signed | The certificate's subject name and the recorded signing time. |
| Trust | Whether the signer's certificate chains to a root trusted by this server. A self-signed or untrusted issuer is reported separately and does not, by itself, mean the signature is invalid. |
| Covers an earlier revision | The signature is intact but a later incremental update was made after it, so it no longer covers the whole file. |
Tips & Notes
A signature can be cryptographically intact yet come from an untrusted issuer (for example a self-signed certificate). The tool reports integrity and trust as two separate facts so you can judge each.
Related tools: Sign PDF · Protect PDF