XAdES

XAdES (XML Advanced Electronic Signatures), set of extensions to XML-DSig making it suitable for advanced electronic signature.

Description

While XML-DSig is general framework for digitally signing XML documents, XAdES specifies precise profiles of XML-DSig for use with qualified electronic signature in the meaning of European Union Directive 1999/93/EC. One important benefit from XAdES is that electronically signed documents can remain valid for long periods, even if underlying cryptographic algorithms are broken.

Profiles

XAdES defines six profiles (forms) differing in protection level offered. Each profile includes and extends the previous one:

• XAdES, basic form just satisfying Directive legal requirements for advanced signature,
• XAdES-T (timestamp), adding timestamp field to protect against repudiation,
• XAdES-C (complete), adding references to verification data (certificates and revocation lists) to the signed documents to allow off-line verification and verification in future (but does not store the actual data),
• XAdES-X (extended), adding timestamps on the references introduced by XAdES-C to protect against possible compromise of certificates in chain in future,
• XAdES-X-L (extended long-term), adding actual certificates and revocation lists to the signed document to allow verification in future even if their original source is not available,
• XAdES-A (archival), adding possibility for periodical timestamping (e.g. each year) of the archived document to prevent compromise caused by weakening signature during long-time storage period.

Links

• W3C XAdES version 1.1.1 from 2003
• ETSI TS 101 903 XAdES version 1.2.2 from 2004
• ETSI TS 101 903 XAdES version 1.3.2 from 2006-03

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