CAdES (CMS Advanced Electronic Signatures) it’s a set of database extensions signed with Cryptographic Message Syntax (CMS) suitable for the advanced electronic signature.
While the CMS format is a CAdES-T (timestamp),a general framework to digitally sign documents like E-Mail (S / MIME) or PDF, CAdES specifies accurate data profiles signed with CMS to be used with the advanced electronic signature in the European Directive 1999/93/CE.
An important advantage of the CAdES format is that electronically signed documents can still be valid after long periods of time even if the underlying cryptographic algorithms are broken
The main document describing this format is the ETSI TS 101 733 Electronic Signature and Infrastructure (ESI) – CMS Advanced Electronic Signature (CAdES)
The CAdES format has 6 different profiles defined, depending on the level of protection offered. Each profile includes and upgrades the previous one. Currently, at Viafirma, we support up to the CAdES-T profile.
- CAdES.Basic form that simply meets the Directive legal requirements for the advanced e-signature
- CAdES-T (timestamp). The time-stamped field is incorporated into it to protect the data from possible repudiation.
- CAdES-C (complete). It is a CAdES-T to which references about the certificates and revocation lists are added and used to allow offline validation and verification in the future (without storing the current verification data).
- CAdES-X (extended). It is a CAdES-C to which information about the date and time of the data entered for extension C is added.
- CAdES-X-L (extended long-term).It is a CAdES-X to which certificates (public key only) and validation sources are incorporated. Ensures long-term off-line validation even if the original source is not available.
- CAdES-A (archived). This format includes all the above but includes meta-information regarding re-signaturing policies. A re-signaturing policy establishes an expiry date of the digital signature and afterwards the re-signaturing process begins. The ideal scenario for this signature format are those documents with a very long validity period: mortgages, university titles, deeds, etc. 15, 20, 50 years, etc.