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Verify Metadata Compress PDF PDF Software

How We Check PDF Digital Signatures

Our PDF Signature Checker analyzes digital signatures embedded in PDF documents. We extract signer identity, certificate validity, timestamps, and verify whether the document has been modified after signing.

What Are PDF Digital Signatures?

A PDF digital signature is a cryptographic mechanism embedded in the document that proves the identity of the signer and ensures the document has not been altered. Digital signatures use public-key infrastructure (PKI) with X.509 certificates to provide tamper-evident protection.

  • Authentication: Confirms the identity of the person or organization that signed the document
  • Integrity: Detects any modifications made to the document after signing
  • Non-repudiation: The signer cannot deny having signed the document
  • Timestamping: Proves when the document was signed using trusted timestamp authorities

Our Verification Process

When you upload a PDF, our system performs a multi-step signature analysis:

1

Signature Detection

We scan the raw PDF binary for /Sig type dictionaries and PKCS#7 signature containers to identify all embedded signatures.

2

Certificate Extraction

From each signature, we extract the X.509 certificate including the signer common name, organization, validity dates, and signing algorithm.

3

Byte Range Analysis

We verify the ByteRange of each signature to determine whether it covers the entire document or if modifications were made after signing.

4

Permissions & Certification

We check for DocMDP certification levels and document permission flags to understand what changes are allowed.

Supported Signature Formats

Our tool supports all major PDF digital signature formats:

  • adbe.pkcs7.detached — Standard PKCS#7 detached signature (most common)
  • adbe.pkcs7.sha1 — Legacy SHA-1 PKCS#7 signature
  • ETSI.CAdES.detached — European standard advanced electronic signature
  • ETSI.RFC3161 — Document-level timestamp signature

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