PAdES, CAdES and XAdES are three implementations of the same advanced-signature (AdES) concept for different content. PAdES embeds signatures in PDFs, CAdES signs arbitrary binary data via CMS, and XAdES signs XML. Choose the one that matches the data you are signing.
| PAdES | CAdES | XAdES | |
|---|---|---|---|
| Signs | PDF documents | Arbitrary binary data | XML documents |
| Built on | PDF + CMS | CMS / PKCS#7 | XML-DSig |
| Standard | ETSI EN 319 142 | ETSI EN 319 122 | ETSI EN 319 132 |
| Placement | Embedded in the PDF | Enveloping or detached | Enveloped, enveloping or detached |
| Baseline levels | B / T / LT / LTA | B / T / LT / LTA | B / T / LT / LTA |
| Common use | Signed contracts & invoices | Machine-to-machine, archival | E-invoicing, e-government |
How they relate
All three share the AdES model — signing certificate, optional timestamps and long-term validation data — and differ only in how the signature is encoded and attached. PAdES is essentially CAdES adapted to live inside a PDF.
When signatures are bundled in an ASiC container, the inner signatures are CAdES or XAdES.
See it on your own documents
Sealium tells you the exact signature level and format of any document you send — PAdES, CAdES, XAdES, JAdES, ASiC or KRX — in one API call. Free for 100 validations a month.
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