PAdES, XAdES and JAdES: Signature Formats Explained

XAdES embeds the signature as an XML element within or alongside the XML document. Widely used in e-government systems (EU member states, LATAM). Supports the same baseline levels (B, T, LT, LTA) as PAdES.

JAdES (JSON Advanced Electronic Signature) is the newest of the three. It signs JSON data using a detached signature model — the signature is a separate JSON object that references the original data. Particularly relevant for EU DPP data signing.

CAdES (CMS Advanced Electronic Signature) is a fourth format for binary data. Less common in practice but used in some PKI infrastructures and for specific regulatory submissions.

Match the format to the document container: PDF → PAdES, XML → XAdES, JSON → JAdES. If you are signing human-readable contracts, PAdES is the right choice. For API-driven data submission (like DPP), JAdES or XAdES is more appropriate.

PAdES signature in PDF: adds 15-50 KB per signature (including certificate + CRL + OCSP + timestamp). XAdES signature in XML: adds 5-20 KB. JAdES signature in JSON: adds 3-15 KB. For batch signing of 10,000 documents, PAdES adds 150-500 MB of overhead; XAdES adds 50-200 MB.

PAdES validation in Adobe Reader: 0.5-2 seconds per signature (includes chain verification + CRL check + timestamp verification). XAdES validation via library: 50-200 ms. JAdES validation: 30-100 ms. For bulk verification of 10,000 signatures, XAdES is 5-10x faster than PAdES.

PAdES B-B/B-T/B-LT signatures display natively in Adobe Reader with green checkmark. XAdES and JAdES signatures do NOT display in Adobe Reader — they require specialised validation tools. For B2C documents (consumer contracts), PAdES is the only format that non-technical recipients can verify visually.

PAdES B-B contains the signature and signing certificate but no timestamp or revocation data. Suitable for internal approvals, low-risk NDAs, and documents with short retention needs. Verification fails after certificate expiry. Most basic eSignature platforms produce B-B level signatures by default.

B-T adds a trusted timestamp, proving the document existed at a specific point in time. B-LT adds certificate revocation data (CRL/OCSP), enabling verification even after the CA goes offline. B-LT is recommended for any contract with a retention period beyond 3 years — which covers most employment, loan, and lease agreements.

B-LTA adds periodic archival timestamps, creating an unbroken chain of evidence. Required for documents with 10+ year retention: real estate deeds, patent filings, regulatory submissions, and permanent corporate records. eSign.AI uses B-LTA for all qualified signature workflows by default, ensuring signatures remain verifiable for the full legal retention period.