PAdES (ETSI EN 319 142) is the standard for advanced electronic signatures embedded directly in a PDF. The signature is part of the file, so the document and its proof of signing travel together and the PDF stays viewable in any reader.
Baseline levels
PAdES defines baseline levels that add longevity: B (basic), T (with a trusted timestamp), LT (with revocation data embedded) and LTA (with an archival timestamp). Higher levels let a signature stay verifiable years later, even after the signing certificate expires.
When you'll see it
PAdES is the most common format for signed contracts, invoices and official PDFs in the EU. A single PDF can carry several PAdES signatures, for example when multiple parties sign in sequence.
Frequently asked questions
How do you validate a PAdES signature?
Extract each embedded signature, verify the signed byte ranges are intact, build the certificate chain to a trusted root, check revocation (OCSP/CRL) and validate any timestamp. A validator like Sealium returns this as a structured report from one /v1/validate call.
Validate a PAdES document free
Send a document to the Sealium API and get back the signature level, signer, certificate chain and timestamps as a structured report. 100 validations a month, free, no card.
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