Proof of Process (PoP): Architecture, Evidence Format, and VDF

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 18 August 2026.¶

Copyright Notice

Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved.¶

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

The rapid proliferation of generative artificial intelligence has created an authenticity crisis in digital discourse. While traditional provenance tracks the "custody of pixels," it fails to attest to the human-driven process of creation. This document specifies the Proof of Process (PoP) protocol, which extends the RATS architecture [RFC9334] to validate the "provenance of effort."¶

Unlike traditional attestation which captures static system state, PoP attests to a continuous physical process. It introduces Proof of Biological Space-Time (PoBST) to enforce temporal monotonicity and Cross-Domain Constraint Entanglement (CDCE) to bind behavioral entropy (human jitter) and physical state (thermodynamics) to the document's evolution.¶

2. Terminology

Attester:

The combination of an Attesting Environment (AE) and Target Environment (TE) responsible for generating PoP Evidence.¶

Checkpoint:

A cryptographic commitment to a block of events and the document state, bound by a VDF.¶

PoBST:

Proof of Biological Space-Time. A memory-hard sequential function with asymmetric verification, entangled with human jitter.¶

CDCE:

Cross-Domain Constraint Entanglement. The method of weaving jitter and thermodynamics into the cryptographic chain.¶

3. Core Principles

PoP operates on five primary constraints:¶

• Physics-based Cost: Memory-Hard Sequential Functions (MHSF) establish an economic lower bound on forgery.¶
• Physical Freshness: Replay and simulation attacks are defeated by anchoring sessions to non-deterministic physical markers (thermal noise).¶
• Biological Binding: Captured human motor-signal randomness (jitter) serves as the non-deterministic seed for the spacetime proof.¶
• Out-of-Band Presence: Utilizing secondary physical devices (e.g., smartphone QR scans) to bridge the digital-physical gap.¶
• Asymmetric Verification: PoBST allows complex 10-hour proofs to be verified in milliseconds.¶

4. Attester State Machine

The AE MUST implement the following formal state machine:¶

• RECORDING: AE captures semantic events and physical telemetry into a hash-linked buffer.¶
• PENDING_CHECK: The current event block is frozen to prepare for a checkpoint.¶
• CHECKPOINT: AE computes the VDF over the block hash and incorporates the entangled seed.¶
• SEALING: The Attester generates a final snapshot, signs the transcript root with a hardware Secure Element, and prepares the transport container.¶

5. Attestation Assurance Levels

Attestation Assurance Levels (T1-T4) define the strength of hardware binding, mapping to NIST SP 800-63B Authenticator Assurance Levels (AAL) and EAT security levels [RFC9711].¶

T1: Software-Only

Baseline evidence generation without hardware anchors. Equivalent to AAL1.¶

T2: Attested Software

AE attempts to use platform security APIs (e.g., keychain integration) but degrades gracefully. AAL1-2 equivalent.¶

T3: Hardware-Bound

Requires TPM 2.0 or platform Secure Enclave key binding. Evidence generation MUST fail if hardware is unavailable. AAL3 equivalent.¶

T4: Hardware-Hardened

Maximum assurance with discrete TPM, PUF binding, and enclave execution for timing-sensitive operations. AAL3+ equivalent.¶

6. Evidence Format and CDDL

Evidence Packets are CBOR-encoded and identified by semantic tag 1347571280.¶

      evidence-packet = {
          1 => uint,                              ; version
          2 => tstr,                              ; profile-uri
          3 => uuid,                              ; packet-id
          4 => pop-timestamp,                     ; created
          5 => document-ref,                      ; document
          6 => [+ checkpoint],                    ; checkpoints
          ? 7 => attestation-tier,                ; T1-T4 assurance level
          ? 10 => [+ presence-challenge],         ; QR/OOB proofs
          ? 18 => physical-liveness-section,      ; CDCE markers
      }

      checkpoint = {
          1 => uint,                              ; sequence (strictly monotonic)
          2 => uuid,                              ; checkpoint-id
          3 => pop-timestamp,                     ; timestamp (local)
          4 => hash-value,                        ; content-hash
          5 => uint,                              ; char-count
          6 => edit-delta,                        ; delta
          7 => hash-value,                        ; prev-hash
          8 => hash-value,                        ; checkpoint-hash
          9 => process-proof,                     ; VDF (PoBST)
          10 => jitter-binding,                   ; behavioral-entropy
          11 => physical-state,                   ; CDCE Weave
          12 => bstr .size 32,                    ; entangled-mac (HMAC-SHA256)
      }

      document-ref = {
          1 => hash-value,                        ; content-hash
          3 => uint,                              ; byte-length
          4 => uint,                              ; char-count
          ? 5 => hash-salt-mode,                  ; 0=unsalted, 1=author-salted
          ? 6 => bstr,                            ; salt-commitment
      }

      edit-delta = {
          1 => int,                               ; chars-added
          2 => int,                               ; chars-deleted
          3 => uint,                              ; edit-operations-count
      }

      physical-state = {
          1 => [+ float16],                       ; thermal-trajectory-delta
          2 => uint,                              ; entropy-pool-delta
      }

7. VDF and Temporal Proofs

  hat-seed = H(tpm-monotonic-counter || physical-freshness || document-hash)

8. IANA Considerations

This document requests registration of CBOR tags 1347571280 ("PPP ") and 1463894560 ("WAR "), and the EAT profile urn:ietf:params:rats:eat:profile:pop:1.0 in their respective registries.¶

9. Security Considerations

Author's Address