An XML advanced electronic signature (XAdES) is both:
- an XML digital signature (XMLDSig) as specified in the W3C recommendation XML Signature Syntax and Processing and
- an advanced electronic signature as specified in ETSI EN 319 132-1.
The European Standard (EN) 319 132-1 produced by the European Telecommunications Standards Institute (ETSI) Technical Committee Electronic Signatures and Infrastructures (ESI) defines four levels of XAdES baseline signatures addressing incremental requirements to maintain the validity of the signatures over the long term, in a way that a certain level always addresses all the requirements addressed at levels that are below it:
- The B-B level provides requirements for the incorporation of signed and some unsigned qualifying properties when the signature is generated.
- The B-T level provides requirements for the generation and inclusion, for an existing signature, of a trusted token proving that the signature itself actually existed at a certain date and time. The token itself is a signature issued by a trusted Time Stamping Authority (TSA), which essentially signs the digest of the signature value and a time-stamp produced by the TSA. Thus, the trusted token is a countersignature of the "signature itself" with additional time information.
- The B-LT level provides requirements for the incorporation of all the material required for validating the signature in the signature document. This level aims to tackle the long term availability of the validation material.
- The B-LTA level provides requirements for the incorporation of electronic time-stamps that allow validation of the signature long time after its generation. This level aims to tackle the long term availability and integrity of the validation material.
DokuMate uses XML advanced electronic signatures on the B-T level to sign local or SharePoint Online folders, i.e., all or selected documents contained in a folder and its sub-folders. This allows you to keep track of whether documents are added, removed, renamed, or changed.