APEX Infrastructure

MelbourneVictoriaAustralia kawaljeet.singh3008@gmail.com https://ai-governance-standard.com

This document defines PSI-04, a domain profile of Proof of Stateful Integrity (PSI) for records about vulnerable persons, such as clinical-trial participants and recipients of disability or aged care services. PSI-04 seals each state transition of a record as a PSI receipt chained to the previous one, so that later alteration or omission of a transition is detectable. Only digests are sealed; no personal data leaves the record holder. PSI-04 shows integrity and ordering only and does not show that care was adequate or that any regulation was met. This revision withdraws the multi-party computation and zero-knowledge claims of revision 00 and the request for a URI scheme.

Introduction Records about vulnerable persons are often reviewed long after they are written, and disputes turn on whether entries were changed after the fact. PSI-04 applies the receipt format of to each transition so a reviewer can check that the chain they see is the chain that was sealed. The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

State-Chain Profile Each transition is a JSON object with members subject_ref, state, actor_ref, prev_transition_hash, and salt.

• subject_ref and actor_ref MUST be opaque pseudonymous identifiers held by the record holder; they MUST NOT be names, dates of birth, or government identifiers.
• salt MUST be at least 128 bits of fresh randomness, so the digest cannot be reversed by guessing.
• prev_transition_hash MUST be the PSI record digest of the previous transition for the same subject_ref, or 64 zero characters for the first.

The record holder computes the record digest per and submits only the digest for sealing.

Verification A reviewer given the transitions and receipts verifies each receipt per and checks that every prev_transition_hash equals the digest of its predecessor. A missing, reordered, or altered transition causes a mismatch.

Security Considerations The considerations of apply. In addition, PSI-04 cannot detect a false entry sealed at the time it was made, nor transitions that were never sealed. Linking a pseudonymous reference to a person relies entirely on the record holder's own controls.

IANA Considerations This document has no IANA actions.

References Normative References