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PDF Signature Checker

Verify digital signatures in PDF files and extract certificate details entirely in your browser.

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What is a PDF Signature Checker?

A PDF Signature Checker is a browser-based tool that verifies digital signatures embedded in PDF files. It reads signature data, validates certificate chains, checks document integrity, and extracts detailed certificate information -- all without uploading your files to any server.

Digital signatures in PDFs are used to verify the authenticity of the document and the identity of the signer. They ensure that the document has not been tampered with since it was signed. The signed PDF file has the public certificate embedded in it, so all you need to verify a PDF signature is the file itself.

Key Features

  • Signature Verification: Checks whether the digital signature is cryptographically valid.
  • Authenticity Check: Validates the certificate chain and root CA to confirm the signer's identity.
  • Integrity Check: Detects if the PDF has been modified after signing.
  • Expiry Detection: Identifies expired certificates in the signature chain.
  • Certificate Details: Extracts issuer, subject, validity period, and PEM certificate data for each certificate in the chain.
  • Signature Metadata: Displays signing reason, location, contact info, and signer name when available.
  • Client-Side Processing: All processing happens in your browser -- no files are uploaded or stored externally.
  • Multi-Signature Support: Handles PDF files with multiple digital signatures.

How to Check a PDF Signature

  1. Upload a signed PDF: Click the upload area or drag and drop a digitally signed PDF file.
  2. Automatic verification: The tool immediately reads the signature data and begins verification.
  3. Review results: Check the verification status (Verified, Authenticity, Integrity, Expired) for each signature.
  4. Inspect certificates: View detailed certificate information including issuer, subject, and validity period.
  5. Export PEM data: Expand the PEM certificate section to view or copy the raw certificate data.

For more PDF-related tools, check out our Scanned PDF Converter and PDF Size tools.

Frequently Asked Questions

What types of PDF signatures can this tool verify?

This tool verifies digital signatures embedded in PDF files using public key cryptography. It supports the most common PDF signature formats that embed certificates within the document. The signature must be a standard digital signature created with a certificate that is embedded in the PDF.

Is my PDF file uploaded to any server?

No. All signature verification is performed entirely in your browser using JavaScript. Your PDF file is never uploaded, transmitted, or stored on any server. The entire process is client-side, ensuring your documents remain private and secure.

What is the difference between verified, authenticity, and integrity?

Verified is the overall status indicating whether the signature is cryptographically valid. Authenticity indicates whether the certificate chain is valid and the root CA is trusted. Integrity indicates whether the document content has been modified since it was signed. A document could pass integrity (not tampered) but fail authenticity (untrusted signer), or vice versa.

What information is displayed for each certificate?

For each certificate in the signature chain, the tool displays: common name and organization of both the issuer and subject, certificate validity period (not before/not after dates), country and locality information, and the full PEM-encoded certificate data that can be expanded for inspection.

What is PEM certificate data?

PEM (Privacy-Enhanced Mail) is a base64-encoded format for storing and transmitting cryptographic certificates. The PEM certificate data shown in this tool is the raw certificate that can be decoded to examine all certificate properties, including public key, serial number, signature algorithm, and extensions.

Can I verify multiple signatures in one PDF?

Yes. The tool supports PDF files with multiple digital signatures. Each signature is displayed separately with its own verification status and certificate details. This is useful for documents that require approvals from multiple parties.

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