The difference between basic and medium category is not a nuance: it changes the procedure, the cost and the timeline. Article 38.1 of RD 311/2022 establishes that medium- or high-category systems «shall require an audit for certification of their conformity, without prejudice to the security audit provided for in Article 31, which may also serve for certification purposes», while basic-category systems «shall only require a self-assessment for their declaration of conformity, without prejudice to their also being able to undergo a certification audit». A supplier integrating with the Junta's horizontal platforms often discovers too late that its categorisation moves up and that the self-assessment it was counting on no longer applies. Anticipating it is the difference between planning an audit and suffering one.
Category is not inherited automatically, but it does spread through impact. Categorisation is done under Annex I, assessing the impact an incident would have on information and services across the five dimensions listed in Article 40.2: availability, authenticity, integrity, confidentiality and traceability. If your system handles identities, mediates citizen authentication or supports a service that others depend on, those dimensions score high and the category rises on its own weight. On top of that comes what arrives by contract: Article 2.3 extends the ENS to the systems of private-sector entities when, under a contractual relationship, they provide services or supply solutions to the public sector «for the exercise by these of their administrative competences and powers», and it requires tender specifications to include the requirements needed to ensure ENS conformity of the systems underpinning contractors' services, extending that caution to the supply chain.
In medium category, Annex II activates controls and reinforcements that were not required in basic, and the weight is felt above all in access control (op.acc), monitoring (op.mon), continuity (op.cont) and communications protection (mp.com). The Centro Criptológico Nacional's guides set the bar: CCN-STIC-811 recommends a DMZ in medium and high categories and zone separation, and CCN-STIC-807 sets the admissible algorithms, with SHA-256 as the minimum for medium and high and TLS 1.2 as the minimum version in any case. We carry out the risk analysis with MAGERIT modelled in PILAR, the CCN's methodology and tool; it is worth remembering that this methodology and tool belong to the CCN and do not appear in the articles of the royal decree, which does not impose a specific methodology.