A PDF digital signature can contain a cryptographic digest (a fingerprint of the signed bytes) and certificate data. PDF Signature Checker is a best-effort browser inspector: it looks for signature byte ranges and compares a supported embedded digest with the file’s signed bytes. It does not verify the actual public-key signature, certificate chain, revocation, or signer’s identity.
Check an unsigned test file first
Choose a disposable PDF you made yourself that has no digital signature under Signed PDF, then click Check signatures. The status should say No signatures found and the page should show the same explanation; that is not an error in the PDF. With a PDF containing a supported signature, the tool may display Signature 1 with Integrity, Digest algorithm, Byte range, and descriptive fields if found. Those fields depend on the file; a missing name or date is not automatically a forged signature.
“Intact” is not the same as “valid signer.” It means this parser found digest bytes that matched the chosen ranges, not that it authenticated who signed or validated every PDF revision. For legal or security decisions, use a PDF signature validator with a trusted certificate store and revision-aware checks. Do not share a real signed document or its personal certificate details for a tutorial.
Where your input goes
Processing runs in your browser. The tool does not upload your input to ilham.dev.
Related guide
For more background, read Working With PDFs.
Questions you might have
- Does this prove the signer's identity?
- No. Even an Intact digest here does not verify the public-key signature or trust the certificate. Use a full verifier and independent identity checks when it matters.
- Why is a signature reported as invalid?
- A mismatch can mean the signed byte range changed, or that the format or range was not interpreted as expected. Could not verify can also mean an unsupported digest. Do not infer the cause or the signer’s identity from this lightweight result alone.