SHP Tiers
SHP tiers describe defined security postures.
They are not ratings, product packages, or informal labels such as “good”, “better”, and “best”.
The meaning of a tier depends on the applicable platform specifications, threat model, control catalogue, and certification rules.
Platform-specific meaning
A tier number does not create cross-platform equivalence.
Tier 1 on one platform does not imply the same controls, threat coverage, operational assumptions, or assurance properties as Tier 1 on another.
Each platform defines its own applicable controls and boundaries within the SHP tier framework.
Control sets
A tier is evaluated against its applicable control set.
Controls may include dependencies, applicability conditions, and Non-Negotiable Control status.
Certification decisions are derived from the applicable verification results and tier rules rather than from a percentage score or informal assessment.
Non-Negotiable Controls
Non-Negotiable Controls are mandatory certification gates where applicable.
An applicable NNC cannot be ignored to preserve a desired tier result.
Where NNC failure requires downgrade or refusal under the applicable rules, that result is mechanical.
SHP does not permit discretionary certification overrides.
Full certification
Full-tier certification means that the requirements for full certification at that tier have been satisfied under the applicable platform and certification specifications.
Its meaning remains bounded by:
- the applicable threat model
- the evaluated device
- the evaluated state
- the specification versions
- the certification validity period
Full certification is not a claim of universal security.
Bounded certification
Where permitted, a certification with defined exclusions must be labelled:
Tier X — Bounded Certification
The certification must state the included controls, excluded controls, and residual risk.
Bounded certification must never be represented as equivalent to full-tier certification.
It cannot be used to bypass an applicable Non-Negotiable Control.
Higher tiers
Higher tier numbers represent different defined hardening postures under the applicable platform specifications.
They should not be interpreted merely as a linear security score.
A higher tier may introduce different controls, assumptions, operational constraints, or threat coverage.
The platform specification and control catalogue define the actual meaning.
Certification status is separate from tier
A tier identifies the evaluated hardening posture.
Certification status identifies whether a valid SHP certification currently exists for that evaluated posture.
A previously certified device can therefore become:
Expired — Not Certified
or:
Revoked — Not Certified
without changing the historical meaning of the certification that was originally issued.