PDF Signature Checker

Upload a PDF to detect digital signature fields and markers. Checks for /Sig, /ByteRange, and /SubFilter entries in the PDF structure.

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Frequently Asked Questions

This tool performs a structural analysis of a PDF file to detect digital signature markers such as /Sig, /ByteRange, and /SubFilter fields. It checks whether the PDF contains signature dictionaries, not whether the signatures are cryptographically valid.

No. Cryptographic verification of PDF signatures requires processing X.509 certificates, CRLs, and PKCS#7 data, which cannot be done reliably in a browser. This tool only detects the presence and count of signature fields in the PDF structure.

The tool looks for common signature sub-filters including adbe.pkcs7.detached, adbe.pkcs7.sha1, adbe.x509.rsa_sha1, and ETSI.CAdES.detached. These cover the most common digital signature formats used in PDF documents.