PSI-04: State-Chain Receipts for Records Concerning Vulnerable Persons
draft-singh-apex-psi-04-01

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

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   provisions of BCP 78 and BCP 79.

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   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.

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   Please review these documents carefully, as they describe your rights
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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.

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   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, <https://datatracker.ietf.org/doc/draft-singh-psi/>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, May 2017,
              <https://www.rfc-editor.org/info/rfc8174>.

Author's Address

   Kawaljeet Singh
   APEX Infrastructure
   Melbourne Victoria
   Australia
   Email: kawaljeet.singh3008@gmail.com
   URI:   https://ai-governance-standard.com

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