AdES signature formats

AdES formats - PAdES, XAdES, CAdES, JAdES - are the ETSI standards defining how signatures are embedded in PDF, XML, CMS and JSON data.

AdES (Advanced Electronic Signature) formats are the ETSI standards that define how a signature is embedded in or attached to data: PAdES (EN 319 142) for PDF, XAdES (EN 319 132) for XML, CAdES (EN 319 122) for CMS (Cryptographic Message Syntax) objects and JAdES (TS 119 182) for JSON. The same formats are also used for advanced and qualified electronic seals, not just for signatures. Qualified timestamps are a separate token format, defined in EN 319 422 and based on RFC 3161, which gets embedded inside an AdES signature rather than being an AdES format itself. Data that cannot hold an embedded signature, or that bundles several files together, is instead signed as a detached CAdES or XAdES signature wrapped in an ASiC (EN 319 162) container: the ASiC-S structure for a single signed data object, or the ASiC-E structure for a collection of files. Implementing Decision (EU) 2015/1506, which required public sector bodies handling signed documents across borders to recognise PAdES, XAdES, CAdES and ASiC signatures but not JAdES, is repealed by Implementing Regulation (EU) 2026/248, which adds JAdES to the recognised formats; the new rules apply from 23 February 2027, with signatures in the previously recognised formats remaining recognised until 23 February 2028. Because AdES is a widely adopted standard, most conformant validation tools can process these formats, though support for edge cases varies between implementations.

Each format defines baseline profiles that stack durability: B-B (the basic signature), B-T (adds a timestamp), B-LT (embeds certificates and revocation data) and B-LTA (adds archive timestamps for long-term validation). These baseline profiles are defined within the same standards family, for example EN 319 122-1 for CAdES, EN 319 132-1 for XAdES, EN 319 142-1 for PAdES and TS 119 182-1 for JAdES. Which profile you need depends on how long the document must stay verifiable. The baseline profile is independent of the signature's legal level under eIDAS: a B-B signature can be a simple, advanced or qualified signature, since the legal level depends on the certificate used and, for qualified signatures, a qualified signature creation device, not on the format profile.