QILAHK™ / PROOF SURFACE
Define the Proof Surface Before You Collect Evidence
Turn a broad trust question into a bounded set of claims, criteria, and required observations.
· QILAHK Journal
Begin with the decision
The QILAHK Proof Surface™ describes the evidence boundary around a determination. Start with the decision someone must make: allow an endpoint to connect, accept a supplier assertion, or authorize a software release. Then identify what must be demonstrated for that decision to be defensible.
The boundary should reflect the intended use. Evidence adequate for a low-risk test environment may be inadequate for a production service holding sensitive information.
Map each claim to a test
Break the decision into specific claims and attach an assessment method to each one. A device review might address identity, boot state, software configuration, ownership, and authorization. Each claim needs criteria, an evidence source, and a rule for interpreting missing or conflicting observations.
Avoid collecting an attractive metric merely because a tool exposes it. If a measurement cannot support a defined claim, explain its contextual purpose rather than presenting it as proof.
Make exclusions visible
Every assessment has limits. A configuration review may say little about physical custody. An identity check may establish an account relationship without demonstrating the integrity of the device using it. Write those limits into the assessment scope.
Document assumptions and dependencies as well. If a decision relies on a collector being trustworthy, that dependency belongs in the review. Hidden assumptions make a trust result appear broader than the evidence allows.
Keep the boundary current
A Proof Surface should change when the intended use, environment, or applicable requirements change. Version the scope so a later reviewer can see which boundary applied to an earlier decision.
A practical starting exercise is to write five lines: the decision, the subject, the required properties, the evidence needed, and the exclusions. Expand those lines into criteria before requesting artifacts. This gives collectors a clear purpose and reviewers a clear standard.
Continue exploring the foundations in Cybersecurity Has Security Controls. What It Lacks Is a Trust Layer.
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