Network Working Group K. Singh Internet-Draft APEX Infrastructure Intended status: Informational 13 October 2026 Expires: 16 April 2027 PSI-04: State-Chain Receipts for Records Concerning Vulnerable Persons draft-singh-apex-psi-04-01 Abstract 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. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 16 April 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Singh Expires 16 April 2027 [Page 1] Internet-Draft PSI-04 October 2026 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. State-Chain Profile . . . . . . . . . . . . . . . . . . . . . 2 3. Verification . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 6.1. Normative References . . . . . . . . . . . . . . . . . . 3 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 3 1. 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 [PSI] 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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. 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. Singh Expires 16 April 2027 [Page 2] Internet-Draft PSI-04 October 2026 The record holder computes the record digest per [PSI] and submits only the digest for sealing. 3. Verification A reviewer given the transitions and receipts verifies each receipt per [PSI] and checks that every prev_transition_hash equals the digest of its predecessor. A missing, reordered, or altered transition causes a mismatch. 4. Security Considerations The considerations of [PSI] 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. 5. IANA Considerations This document has no IANA actions. 6. References 6.1. Normative References [PSI] Singh, K., "Proof of Stateful Integrity (PSI): Signed, Merkle-Committed Receipts for Digital Records", Work in Progress, Internet-Draft, draft-singh-psi-02, October 2026, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017, . Author's Address Kawaljeet Singh APEX Infrastructure Melbourne Victoria Australia Email: kawaljeet.singh3008@gmail.com URI: https://ai-governance-standard.com Singh Expires 16 April 2027 [Page 3]