Spend Receipts and Payment Rail Reconciliation for AI Agents
draft-dogru-cedulon-core-00
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| Author | Emek Can Doğru | ||
| Last updated | 2026-09-17 | ||
| Replaces | draft-dogru-cedulon | ||
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draft-dogru-cedulon-core-00
Network Working Group E. C. Dogru
Internet-Draft VERAX TEKNOLOJI LIMITED SIRKETI
Intended status: Informational 17 September 2026
Expires: 21 March 2027
Spend Receipts and Payment Rail Reconciliation for AI Agents
draft-dogru-cedulon-core-00
Abstract
This document addresses auditable payments for AI agents and builds
upon state-of-the-art HTTP 402, AP2 and credit card systems. We
specify a cryptographically secured payment reconciliation protocol
using a Trade Manifest (a signed offer before payment), a Policy
Decision Point with default deny, a Spend Receipt (a COSE/CWT claim
set issued after a gated payment), and rail-extract reconciliation.
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 21 March 2027.
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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Policy Decision Point . . . . . . . . . . . . . . . . . . 6
3.2. Receipt Issuer . . . . . . . . . . . . . . . . . . . . . 6
3.3. Anchor / SCITT . . . . . . . . . . . . . . . . . . . . . 7
4. Lifecycle . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Trade Manifest . . . . . . . . . . . . . . . . . . . . . . . 7
6. Spend Receipt . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Optional payee countersignature . . . . . . . . . . . . . 10
7. COSE Profile . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Claim labels . . . . . . . . . . . . . . . . . . . . . . 11
7.2. COSE_Sign1 headers . . . . . . . . . . . . . . . . . . . 14
7.3. How a signed object is presented . . . . . . . . . . . . 15
8. Canonical JSON encoding . . . . . . . . . . . . . . . . . . . 15
8.1. Which octets are hashed . . . . . . . . . . . . . . . . . 16
9. Decision Token . . . . . . . . . . . . . . . . . . . . . . . 18
10. Rail Extract Profile . . . . . . . . . . . . . . . . . . . . 19
10.1. Record schema . . . . . . . . . . . . . . . . . . . . . 19
10.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.3. Authentication . . . . . . . . . . . . . . . . . . . . . 21
10.4. Scope agreement . . . . . . . . . . . . . . . . . . . . 22
11. Trust roots . . . . . . . . . . . . . . . . . . . . . . . . . 22
11.1. The issuer root . . . . . . . . . . . . . . . . . . . . 23
11.2. The payee root . . . . . . . . . . . . . . . . . . . . . 26
11.3. The decision root . . . . . . . . . . . . . . . . . . . 26
11.4. The manifest root . . . . . . . . . . . . . . . . . . . 26
11.5. What the roots do not cover . . . . . . . . . . . . . . 28
12. Reconciliation . . . . . . . . . . . . . . . . . . . . . . . 28
12.1. Verification algorithm . . . . . . . . . . . . . . . . . 29
12.2. Finding codes . . . . . . . . . . . . . . . . . . . . . 33
13. Policy Semantics . . . . . . . . . . . . . . . . . . . . . . 34
14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 35
15. Security Considerations . . . . . . . . . . . . . . . . . . . 36
15.1. T1: Prompt injection leads to unauthorized spend . . . . 36
15.2. T2: Runaway agent (loop spend) . . . . . . . . . . . . . 37
15.3. T3: Replay of payment authority . . . . . . . . . . . . 38
15.4. T4: Receipt forgery or repudiation . . . . . . . . . . . 38
15.5. T5: Policy bypass via direct rail access . . . . . . . . 41
15.6. T6: Time-of-check to time-of-use (TOCTOU) between policy
check and payment . . . . . . . . . . . . . . . . . . . 42
15.7. T7: Signing-key leakage . . . . . . . . . . . . . . . . 44
15.8. T8: Counterparty price gouging or defective delivery . . 44
15.9. Optional escrow role . . . . . . . . . . . . . . . . . . 46
15.10. T9: Personally identifiable information (PII) leakage into
the transparency log . . . . . . . . . . . . . . . . . 47
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15.11. T10: Secret spend via rail bypass . . . . . . . . . . . 47
15.12. T11: Checkpoint suppression or rollback . . . . . . . . 51
15.13. T12: Settlement without a recorded receipt . . . . . . . 51
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 52
16.1. application/cedulon-receipt+cbor . . . . . . . . . . . . 53
16.2. application/cedulon-manifest+cbor . . . . . . . . . . . 54
16.3. application/cedulon-decision+cbor . . . . . . . . . . . 55
16.4. application/cedulon-countersign+cbor . . . . . . . . . . 55
17. Implementation Status . . . . . . . . . . . . . . . . . . . . 56
18. Evolution and Future Work (Informative) . . . . . . . . . . . 58
19. Informative Notes on Adjacent Protocols . . . . . . . . . . . 58
20. References . . . . . . . . . . . . . . . . . . . . . . . . . 59
20.1. Normative References . . . . . . . . . . . . . . . . . . 59
20.2. Informative References . . . . . . . . . . . . . . . . . 60
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 63
Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 64
Appendix B. Finding Codes . . . . . . . . . . . . . . . . . . . 65
Appendix C. Worked Example: A 10.00 TRY Spend . . . . . . . . . 71
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 72
1. Introduction
Artificial Intelligence (AI) agents involved in travel, stock market
transactions, etc. may need the capability of securely paying for
their transactions. Previously defined protocols such as HTTP 402
[X402] and Google's Agent Payments Protocol (AP2) [AP2] made it
possible: HTTP 402 protocols attach stablecoin settlement to ordinary
requests, and AP2 binds user intent to signed mandates. Card
networks and processors issue agent-scoped tokens.
What is missing is an interoperable *audit layer*: a machine-
checkable answer to "was this spend allowed by policy, against which
offer, and what bytes were delivered?" The answers have limits, and
this document states them. "Allowed by policy" is the Receipt
Issuer's signed assertion; the audit does not independently re-verify
the policy decision (Section 13). What was delivered is machine-
checkable only where an attributable payee countersignature binds a
delivery hash (Section 6.1). Without such a layer, a prompt-injected
or looping agent can drain a rail that has already accepted a valid
signature, and a counterparty can ship the wrong artifact.
The name Cedulon is from cedule, the older legal word for a written
schedule or note. Cedulon does not clear funds, hold custody, or
operate a payment facilitator. An optional escrow actor is defined
only as a third-party role interface (Section 15.9). Implementations
of this specification MUST NOT take custody of funds or operate
escrow (MUST-T8-custody).
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Reconciling an internal ledger against an external statement is an
old accounting control [PACIOLI], and signing the artifacts on both
sides is Grigg's triple-entry idea [GRIGG]. This document profiles
that control for parties that are software: a CBOR Object Signing and
Encryption (COSE) [RFC9052] receipt shape, an extract shape, and a
verification algorithm precise enough that two implementations reach
the same finding on the same evidence. The checkpoint chain that
extends it over time is in [CEDULON-CHECKPOINT].
A Cedulon audit is intended to be read within the architecture for
auditing AI agent delegation and interactions [KUEHLEWIND-AUDIT],
which links user intent, delegation and authorization to an
execution, registers the resulting records with a Supply Chain
Integrity, Transparency, and Trust (SCITT) Transparency Service
[RFC9943], and lists financial transactions by agents among its
motivating cases. For a spend, this document adds a result that
architecture does not define: completeness of signed receipts against
an authenticated extract of the rail, over a declared account, rail
and time window. This document does not define an integration
profile for that architecture. Other related drafts are noted in
Section 19.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" 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.
This document uses Concise Binary Object Representation (CBOR)
[RFC8949], CBOR Web Token (CWT) [RFC8392] claim sets, and JavaScript
Object Notation (JSON) documents. In the tables, CBOR types are
written tstr (text string), bstr (byte string) and uint (unsigned
integer).
The following terms are used:
Trade Manifest: A signed statement produced *before* payment. It
binds a description of goods or service, price, currency,
acceptance-criteria hash, cancel condition, expiry, and an
optional AP2 mandate reference.
Policy Decision Point (PDP): The function that evaluates a
structured spend request against stored policy. The default is
deny.
Rail: The payment system that moves value and reports what it
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settled, such as the settlement path behind an HTTP 402 exchange
[X402]. A Rail Extract names it by railId.
Payment Adapter: The component that performs the payment on the
rail. It calls the PDP first and is the only path from the agent
to the rail (MUST-T5-1).
Spend Receipt: A signed statement produced *after* a gated payment
attempt. It binds payer, payee, amount, currency, policy hash,
manifestHash or an explicit noManifest flag, rail payment
reference, timestampMs, nonce, prevReceiptHash, and outcome.
Receipt Issuer: The party that signs Spend Receipts.
Anchor: An optional SCITT Transparency Service [RFC9943] that
registers a signed statement and returns a COSE receipt [RFC9942].
Dispute Evidence Bundle: A package of the Trade Manifest, the Spend
Receipt, and a delivery hash. It is evidence for a later human or
legal process. It is not an arbitral award and not an escrow
release.
Decision Token: A portable, single-use PDP allow encoded as
COSE_Sign1. The claim set binds requestHash, policyHash,
expiryMs, nonce, and singleUseId. See Section 9.
Rail Extract: An authenticated list of settlement records for one
account, one rail, and one time window. See Section 10.
Verifier: The party that runs the reconciliation of Section 12 over
the receipts, the Rail Extract, and the keys it holds.
Pinned key: A public key the verifier obtained out of band, as
opposed to a key an object carries beside its signature. See
Section 11.
Working set: The receipts and checkpoints the verification steps
consume: those that verify under a usable pinned issuer key (the
attested set), or, when no usable issuer key is pinned, every
presented one. See Section 12.1.
Presented-unattested: The state of a receipt or checkpoint the
verifier holds no pinned issuer key for. Its signature is checked
against the key the object itself carries (Section 7.3), which
establishes internal consistency only, so the object is neither
attested nor rejected: every presented object is weighed as one
set and the completeness guarantee is reported as conditional. It
is a state of the report, not a finding code. See Section 11.1.
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3. Architecture
The following diagram shows the payment path, the audit path, and the
optional transparency service:
Principal --policy--> PDP
^
| request / allow or deny
Trade Manifest |
(optional) -----> Payment Adapter --payment--> Rail
| |
v v
Receipt Issuer Rail Extract
| |
v |
Spend Receipt ---> Verifier <---+
| |
v v
Anchor / SCITT (optional) Report
The payer agent never talks to the rail except through an adapter
that calls the PDP first (MUST-T5-1).
3.1. Policy Decision Point
The PDP evaluates structured fields only (MUST-T1-1): amount,
currency, payee, tool identifier, nonce, optional manifest hash, and
evaluation time. It applies limit, velocity, and scope checks (MUST-
T2-1, MUST-T2-2). If the PDP is unreachable, uninitialized, or
throws, the result is deny (MUST-T2-3). Denied attempts do not
increment success counters (MUST-T2-4).
An allow produces a Decision Token whose requestHash covers six
fields: amount, currency, payee, tool, nonce, and manifestHash (MUST-
T3-4, MUST-T6-1). The token is a COSE_Sign1 object (MUST-T6-4), is
single-use (MUST-T6-2), and MAY be carried to the adapter that
performs settlement.
3.2. Receipt Issuer
After the adapter attempts settlement (success or a recorded deny
that still needs an audit trail for an allowed-then-aborted path),
the Receipt Issuer signs a Spend Receipt over the deterministic CBOR
encoding of its claims (MUST-T4-1). Verifiers reject bad signatures
and byte mismatch (MUST-T4-2).
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3.3. Anchor / SCITT
Parties MAY register the signed receipt (or a privacy-preserving hash
encoding) as a SCITT Signed Statement [RFC9943] and attach the COSE
receipt (MAY-T4-6). This document does not operate a Transparency
Service.
4. Lifecycle
1. *Manifest.* Optionally, the payee or a marketplace signs a Trade
Manifest. A spend without one is marked noManifest and still
passes limit, velocity and scope checks (MUST-T1-2); a deployment
MAY refuse such spend (MAY-T1-4).
2. *Policy check.* The adapter submits a structured request to the
PDP. Default is deny. An allow is a Decision Token (MUST-T6-4).
3. *Payment.* On allow, the adapter performs the x402 (or other
rail) exchange using exactly the decision fields (MUST-T6-1).
The Decision Token is consumed (MUST-T6-2). A reused nonce is
denied (MUST-T3-1, MUST-T3-2). A tampered or expired token is
denied (MUST-T6-5).
4. *Receipt.* The Receipt Issuer signs a Spend Receipt. Rail
credentials MUST NOT appear in the receipt, logs, or tool results
(MUST-T5-2, MUST-T7-1).
5. *Dispute Evidence Bundle.* If delivery bytes do not match the
acceptance-criteria hash, an implementation MUST be able to emit
a bundle of manifest + receipt + delivery hash (MUST-T8-3). The
bundle MUST NOT be described as an arbitral award or escrow
release (MUST-T8-4).
Afterwards, a verifier reconciles the receipts against the rail's own
extract (Section 12). Appendix C follows one 10.00 TRY spend through
these steps.
5. Trade Manifest
A Trade Manifest is a signed offer issued *before* value moves. It
MAY carry an AP2 mandate hash so that user intent and the offer stay
linked (SHOULD-T8-5).
A Trade Manifest MUST bind all of the following (MUST-T8-1):
* goods or service description
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* price (integer minor units, encoded as a decimal string matching
0|[1-9][0-9]*)
* currency (ISO 4217 alphabetic or a documented token identifier)
* acceptance-criteria hash (SHA-256 [RFC6234] of the exact delivery
bytes, lowercase hexadecimal)
* cancel condition (opaque string agreed by the parties)
* expiry (POSIX milliseconds, expiresAtMs)
The hash is taken over the exact delivery bytes only. Hashing a
schema instance instead would need a marker in the manifest saying
so; this document defines no such marker, and until one is defined
that use is out of scope rather than an alternative a verifier is
expected to guess at. The acceptance-criteria hash therefore fits a
delivery whose exact bytes are known when the offer is signed, such
as a file; this document defines no such hash for a service, such as
a travel booking, whose delivery is not a byte string.
It MAY include ap2MandateHash. The corresponding CBOR label is
always present; a missing mandate is encoded as CBOR null.
It MAY name a payee. An offer that is specific to one counterparty
carries that party's payee identifier; when present, every receipt
that names this manifest has its payee compared against it as exact
octets under MUST-T8-9, on that requirement's two-branch severity.
An open offer legitimately omits the member, and no comparison is
made. Unlike ap2MandateHash, the label is encoded only when the
member is present, so the null convention above does not apply to it.
The manifest is COSE_Sign1 [RFC9052] over a deterministic CBOR claim
map (Section 7). manifestHash is the SHA-256 of the signed COSE bytes
(MUST-T8-7). A spend bound to a manifest MUST be denied if the
requested amount or currency differs from the manifest (MUST-T8-2) or
if the manifest is expired (MUST-T3-3).
A spend that is not bound to a verified manifest MUST be marked
noManifest on the receipt and MUST still pass limit, velocity, and
scope checks (MUST-T1-2). An implementation MAY refuse all
noManifest spend (MAY-T1-4).
6. Spend Receipt
The Spend Receipt claim set is carried in COSE_Sign1 [RFC9052]
wrapping a CWT-compatible map [RFC8392]. New receipts MUST use the
COSE profile (Section 7).
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Claims (MUST-T4-3, MUST-T4-4, MUST-T4-7):
+=================+===============================================+
| Claim | Description |
+=================+===============================================+
| payer | Payer agent identifier |
+-----------------+-----------------------------------------------+
| payee | Payee identifier |
+-----------------+-----------------------------------------------+
| amount | Minor units as a decimal string 0|[1-9][0-9]* |
+-----------------+-----------------------------------------------+
| currency | Currency identifier |
+-----------------+-----------------------------------------------+
| policyHash | SHA-256 of the canonical policy document |
| | (lowercase hex) |
+-----------------+-----------------------------------------------+
| manifestHash | SHA-256 of the signed manifest COSE bytes, or |
| | null when noManifest is true |
+-----------------+-----------------------------------------------+
| noManifest | Boolean; MUST be true if and only if |
| | manifestHash is null |
+-----------------+-----------------------------------------------+
| x402PaymentRef | Rail payment reference, or null |
+-----------------+-----------------------------------------------+
| timestampMs | POSIX milliseconds |
+-----------------+-----------------------------------------------+
| nonce | Unique spend nonce; at least 128 bits of |
| | randomness; unique in the issuer scope |
+-----------------+-----------------------------------------------+
| prevReceiptHash | Previous receipt hash, or null for the first |
| | receipt (SHOULD-T4-5) |
+-----------------+-----------------------------------------------+
| outcome | settled or aborted |
+-----------------+-----------------------------------------------+
Table 1
A receipt with outcome = settled MUST have a non-null x402PaymentRef
(MUST-T4-7). An aborted receipt MUST NOT be added into checkpoint
totals.
All twelve labels in Section 7.1 are always present. An empty
optional value is encoded as CBOR null, never by omitting the label.
receiptHash is the SHA-256 of the receipt's signed COSE bytes,
encoded as lowercase hex.
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Verifiers MUST reject a receipt if the signature fails or if the
decoded claim map does not match the presented claims (MUST-T4-2).
6.1. Optional payee countersignature
A payee MAY attach a countersignature over the issuer's signed Spend
Receipt (MAY-T8-10). The profile uses a *detached* COSE_Sign1
[RFC9052] whose payload is a CBOR map with private-use labels:
+========+===============+======================================+
| Label | Claim | CBOR type |
+========+===============+======================================+
| -70401 | receiptCose | bstr (exact issuer COSE_Sign1 bytes) |
+--------+---------------+--------------------------------------+
| -70402 | deliveredHash | bstr (optional; SHA-256 of the exact |
| | | delivered bytes) |
+--------+---------------+--------------------------------------+
Table 2
The countersignature uses the header profile in Section 7 and content
type application/cedulon-countersign+cbor.
This is a second Sign1 object, not RFC 9052 Countersignature0
(unprotected-header label 11). Countersignature0 would write into
the issuer object and change receiptHash after issue, breaking the
receipt chain. A detached Sign1 keeps the issuer bytes stable,
reuses kid and content-type, and is absent by simply omitting the
sibling object.
Absence of a countersignature MUST NOT invalidate the issuer receipt
(MAY-T8-10). A countersignature travels beside the issuer signature
without being covered by it, so anyone holding an honest receipt can
append one of their own. Attribution is therefore the gate: a
countersignature that cannot be attributed to the pinned payee key -
the signature fails, kid or content type does not match, label -70401
is not the issuer COSE bytes (MUST-T8-8), or the signature is valid
under some other key - MUST be rejected as approval evidence. What
is rejected is the countersignature, not the receipt: the verdict on
the untouched issuer receipt MUST NOT change because an
unattributable object was attached. An appendable object the issuer
signature does not cover must not be able to manufacture a negative
result. The identifiers countersign-bad (unverifiable) and
countersign-key-mismatch (verifiable under another key) name the
discarded object as warnings, and where the verifier pinned a payee
key and no attributable countersignature remains, the countersign-
missing warning still applies: a discarded forgery is the absence of
the payee's word, not a substitute for it.
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The optional deliveredHash claim binds delivery to the receipt under
the payee's key. A payee who countersigns MAY include the SHA-256 of
the exact bytes it delivered in the same signed payload as the issuer
receipt bytes. When an attributable countersignature carries
deliveredHash and the verifier also holds the Trade Manifest, the two
digests are compared as exact octets: deliveredHash against
acceptanceCriteriaHash. A mismatch is delivery-mismatch, and it is a
finding rather than a warning, because both ends of the comparison
are signed. A deliveredHash carried by an unattributable
countersignature is discarded with it. A countersigner MUST refuse
to sign a deliveredHash that is not 32 octets; a verifier that meets
one anyway treats the countersignature as carrying no deliveredHash,
so the delivery question narrows as it does when the claim is absent,
and the signature verdict does not move. A countersignature without
the claim remains valid.
A Dispute Evidence Bundle that includes a verified countersignature
has stronger evidence that the payee accepted those bytes; the bundle
is still not an award (MUST-T8-4).
7. COSE Profile
This profile uses deterministic CBOR [RFC8949] Section 4.2.1
(definite lengths, shortest integer form, map keys sorted in
*bytewise lexicographic* order of their encoded keys).
Implementations MUST encode only the types used by Cedulon claim
maps: null, bool, unsigned and negative integers, UTF-8 text, byte
strings, arrays, and maps (MUST-T4-1).
A decoder MUST refuse a CBOR map that carries a duplicate encoded key
(MUST-T4-18).
A decoder MUST also impose a bound on what it will attempt: on
encoded size, on nesting depth, and on the number of elements it will
decode from an audit input. It MUST refuse an input that exceeds a
bound with a named refusal rather than by exhausting memory or the
stack, and it SHOULD document the bounds it applies (MUST-T4-19).
This document fixes no numbers, because the right bounds depend on
the deployment; what it requires is that exceeding a bound is a
named, reported refusal rather than a crash.
7.1. Claim labels
Registered CWT claims [RFC8392] are not required by this profile.
Cedulon uses CWT private-use integer labels less than -65536.
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Every claim the tables below annotate as hash carries a SHA-256
digest rendered as exactly 64 lowercase hexadecimal characters ([0-
9a-f]{64}). A signer MUST refuse to sign, and a validator MUST
reject, a value that does not match that grammar, naming the claim in
the refusal. A decoder that preserves unknown or foreign claims is a
separate layer and keeps them unchanged; the grammar binds what a
party signs and what a validator accepts, not what a decoder can
carry.
Receipt labels (MUST-T4-3, MUST-T4-4, MUST-T4-7):
+========+=================+==========================+
| Label | Claim | CBOR type |
+========+=================+==========================+
| -70001 | payer | tstr |
+--------+-----------------+--------------------------+
| -70002 | payee | tstr |
+--------+-----------------+--------------------------+
| -70003 | amount | tstr |
+--------+-----------------+--------------------------+
| -70004 | currency | tstr |
+--------+-----------------+--------------------------+
| -70005 | policyHash | tstr (hash) |
+--------+-----------------+--------------------------+
| -70006 | manifestHash | tstr (hash) / null |
+--------+-----------------+--------------------------+
| -70007 | noManifest | bool |
+--------+-----------------+--------------------------+
| -70008 | x402PaymentRef | tstr / null |
+--------+-----------------+--------------------------+
| -70009 | timestampMs | uint |
+--------+-----------------+--------------------------+
| -70010 | nonce | tstr |
+--------+-----------------+--------------------------+
| -70011 | prevReceiptHash | tstr (hash) / null |
+--------+-----------------+--------------------------+
| -70012 | outcome | tstr (settled / aborted) |
+--------+-----------------+--------------------------+
Table 3
Checkpoint labels (MUST-T11-1):
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+========+====================+=========================+
| Label | Claim | CBOR type |
+========+====================+=========================+
| -70101 | epoch | uint |
+--------+--------------------+-------------------------+
| -70102 | startMs | uint |
+--------+--------------------+-------------------------+
| -70103 | endMs | uint |
+--------+--------------------+-------------------------+
| -70104 | receiptCount | uint |
+--------+--------------------+-------------------------+
| -70105 | chainHeadHash | tstr (hash) / null |
+--------+--------------------+-------------------------+
| -70106 | totals | map tstr -> tstr / null |
+--------+--------------------+-------------------------+
| -70107 | prevCheckpointHash | tstr (hash) / null |
+--------+--------------------+-------------------------+
Table 4
Manifest labels (MUST-T8-1):
+========+========================+=========================+
| Label | Claim | CBOR type |
+========+========================+=========================+
| -70201 | description | tstr |
+--------+------------------------+-------------------------+
| -70202 | amount | tstr |
+--------+------------------------+-------------------------+
| -70203 | currency | tstr |
+--------+------------------------+-------------------------+
| -70204 | acceptanceCriteriaHash | tstr (hash) |
+--------+------------------------+-------------------------+
| -70205 | cancelCondition | tstr |
+--------+------------------------+-------------------------+
| -70206 | expiresAtMs | uint |
+--------+------------------------+-------------------------+
| -70207 | ap2MandateHash | tstr (hash) / null |
+--------+------------------------+-------------------------+
| -70208 | payee | tstr (optional; encoded |
| | | only when present) |
+--------+------------------------+-------------------------+
Table 5
Decision Token labels (MUST-T6-4):
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+========+=============+=============+
| Label | Claim | CBOR type |
+========+=============+=============+
| -70301 | requestHash | tstr (hash) |
+--------+-------------+-------------+
| -70302 | policyHash | tstr (hash) |
+--------+-------------+-------------+
| -70303 | expiryMs | uint |
+--------+-------------+-------------+
| -70304 | nonce | tstr |
+--------+-------------+-------------+
| -70305 | singleUseId | tstr |
+--------+-------------+-------------+
Table 6
7.2. COSE_Sign1 headers
The protected header MUST be a deterministic CBOR map containing
(MUST-T4-1, MUST-T4-8):
* 1 (alg) = -19 (Ed25519, [RFC9864]; the generic EdDSA value -8 from
[RFC9053] is deprecated for this profile)
* 3 (content type) = a tstr that distinguishes the payload:
application/cedulon-receipt+cbor, application/cedulon-
checkpoint+cbor, application/cedulon-manifest+cbor, application/
cedulon-decision+cbor, application/cedulon-countersign+cbor, or
application/cedulon-inclusion+cbor
* 4 (kid) = bstr, mandatory. The profile computes kid as the first
eight bytes of SHA-256 over the issuer's SubjectPublicKeyInfo DER,
in the Ed25519 SubjectPublicKeyInfo encoding of [RFC8410]. A
verifier MUST obtain the public key from an authenticated channel
(preconfigured issuer set, directory, or transparency statement)
and MUST reject a message whose kid does not match that key.
The unprotected header MUST be empty, and a decoder MUST refuse a
message whose unprotected header is not an empty map, by the name
cose-sign1-unprotected, rather than verify the signature and ignore
the header (MUST-T4-21): every digest in Section 8.1 is computed over
octets that include the unprotected header, which the signature does
not cover. The payload MUST be the CBOR encoding of the claim map.
The signature is Ed25519 [RFC8032] over the COSE Sig_structure
["Signature1", protected, h'', payload].
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7.3. How a signed object is presented
The signed octets above are what this profile defines and what every
digest in Section 8.1 is taken over. An object handed to a verifier
travels with more than that, and this section names what.
A presented Spend Receipt, epoch checkpoint, Trade Manifest, or
Decision Token carries, beside the signed octets, its claim set or
body in decoded form and *the signer's public key as a
SubjectPublicKeyInfo PEM*; a countersigned receipt carries the
payee's key the same way, and an object presented in the JSON
encoding of Section 8 repeats its signature there as base64. None of
these is inside the signed octets, which is the whole point of naming
them here: the signature covers the COSE message and nothing else, so
every one of these members is a surface anyone holding the object can
rewrite. This is the same shape the Rail Extract states in
Section 10, and it is stated once here for the COSE objects rather
than left to be inferred from an implementation.
A carried key is not an identity source and MUST NOT be used as one
(MUST-T4-11). Under a pin it has exactly one effect: an object that
verifies under the pinned key while carrying a different key is
reported as carried-key-mismatch, a warning, and stays attested
(Section 11.1). With no pin held it is the only key present, so any
signature check that runs against it says the object is internally
consistent and says nothing about who signed it; two issuers cannot
be told apart in that state. A Trade Manifest with no pinned key is
not checked against its carried key at all (Appendix B,
unauthenticated-manifest).
8. Canonical JSON encoding
Not everything this document hashes or signs is CBOR. The policy
document, the six request fields bound by a Decision Token, and the
scoped body of a Rail Extract are JSON. Two implementations could
agree on every other requirement in this document and still produce
different bytes unless the encoding is named, which makes an
independent verifier impossible to write from the text. This section
names that encoding.
Where this document says "the canonical encoding" of a JSON document,
it means the encoding defined by [RFC8785], and the octets hashed or
signed are the UTF-8 octets of that encoding.
Three notes on the boundary of that reference:
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* [RFC8785] Section 3.1 takes I-JSON [RFC7493] as its input, and an
I-JSON object carries no duplicate member names. This document
makes that precondition a rule at every place a verifier receives
a JSON document as text - a rail extract body, a policy document,
a stored receipt file: a text in which any object, at any depth,
repeats a member name MUST be refused by the name json-duplicate-
key, before the text is parsed (MUST-T4-20). A verifier handed an
object rather than text, as a tool behind a JSON-RPC boundary is,
cannot apply the rule and MUST NOT report that it did; whether the
text was checked is then the transport's to state.
* [RFC8785] Section 3.2.2.2 requires a serializer to terminate on a
lone surrogate, and so does this document: a producer MUST refuse
to encode a document containing one, by name, and MUST NOT sign
what it could not encode. A verifier reading bytes it cannot
canonicalize for this reason reports the input as failing
verification with the refusal named beside the verdict; it does
not crash. No field defined by this document may contain a lone
surrogate, so a conforming document never reaches this rule.
* [RFC8785] defines no encoding for an integer outside the IEEE 754
double range. No document defined here carries one: every amount
and cumulative limit is already a decimal string before it is
encoded, and every hash is lowercase hexadecimal. A document that
would need such an integer is outside this specification.
8.1. Which octets are hashed
Every hash-valued field in this document is SHA-256 [RFC6234] of the
input named below. All but two are rendered as lowercase
hexadecimal, and a third differs in another respect. kid differs only
in its rendering: the digest is computed over the same stated input
and then truncated to its first 8 bytes, carried as a byte string
rather than as hex (Section 7 states the same rule where the header
is defined). ap2MandateHash differs in whose digest it is: AP2
defines the mandate and its octets, and this document carries the
result opaquely rather than restating a rule it does not own.
deliveredHash differs in its carrier: it is a claim in a CBOR map and
is carried as the raw 32 digest bytes (bstr), not as hex; comparisons
against acceptanceCriteriaHash are made over the digest value.
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+========================+======================================+
| Field | Input to SHA-256 |
+========================+======================================+
| receiptHash | the signed COSE_Sign1 octets of the |
| | receipt |
+------------------------+--------------------------------------+
| manifestHash | the signed COSE_Sign1 octets of the |
| | Trade Manifest |
+------------------------+--------------------------------------+
| checkpointHash | the signed COSE_Sign1 octets of the |
| | checkpoint |
+------------------------+--------------------------------------+
| statementHash | the signed COSE_Sign1 octets of the |
| | statement |
+------------------------+--------------------------------------+
| acceptanceCriteriaHash | the exact delivery bytes, as defined |
| | in Section 5 |
+------------------------+--------------------------------------+
| deliveredHash | the exact bytes the payee delivered, |
| | under the same input rule as |
| | acceptanceCriteriaHash, computed by |
| | the payee when it countersigns |
+------------------------+--------------------------------------+
| policyHash | the UTF-8 octets of the canonical |
| | policy document |
+------------------------+--------------------------------------+
| requestHash | the UTF-8 octets of the canonical |
| | six-field request document |
+------------------------+--------------------------------------+
| kid | the SubjectPublicKeyInfo DER; the |
| | digest is then truncated to its |
| | first 8 bytes |
+------------------------+--------------------------------------+
| ap2MandateHash | the octets AP2 defines for its |
| | mandate; not profiled by this |
| | document |
+------------------------+--------------------------------------+
Table 7
Wherever this table, or any other sentence in this document, says
"the signed COSE_Sign1 octets", those are the octets of the
*untagged* four-element COSE_Sign1 array of [RFC9052]. This profile
never wraps a message in CBOR tag 18, and the vectors in Appendix A
carry the untagged form. A verifier that hashed a tagged copy would
compute a different digest for every object in this profile, so the
choice is stated here once rather than left to be inferred from the
vectors.
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The six fields of the request document are the ones MUST-T6-1 names:
amount, currency, payee, tool, nonce, and manifestHash.
The request document is a JSON object carrying exactly those six
members and no others, every member always present. amount is the
decimal string of the request, in the amount syntax the receipt
claims table states, never a JSON number: [RFC8785] encodes the
number 1 and the string "1" differently, and an implementation free
to pick either would produce two digests for one request. currency,
payee, and nonce are the request's text strings. tool is the
request's text string, or JSON null where the deployment names none.
manifestHash is the lowercase hexadecimal string, or JSON null for a
spend bound to no manifest; an absent value is null, never an omitted
member. A document with a seventh member, a missing member, or
another type for one of these is not the request document this
section defines.
The policy document is different on purpose, and the difference is
scope rather than an oversight. Its member set is the deployment's
own: this document defines how the bytes of whatever policy document
a PDP evaluates are encoded (Section 8) and digested, not what its
members are. policyHash binds a spend to the exact bytes its PDP
evaluated; it is not a value two deployments are expected to compute
from a shared schema, and nothing in the verification algorithm
compares one deployment's policyHash to another's.
9. Decision Token
A Decision Token is the portable encoding of a PDP allow. It is
COSE_Sign1 with the header profile in Section 7 and the labels in
Section 7.1. All five labels are always present (MUST-T6-4).
requestHash MUST be the SHA-256 of the canonical encoding of the six
fields the PDP evaluated (MUST-T6-1), rendered as lowercase
hexadecimal; Section 8 defines that encoding and Section 8.1 states
the octets. policyHash MUST be the SHA-256 of the canonical policy
document the PDP evaluated. expiryMs is a Unix time in milliseconds
after which the token MUST be treated as expired (SHOULD-T6-3):
expired when the evaluation time is strictly greater than expiryMs,
not yet expired at exactly expiryMs, on the same boundary discipline
MUST-T3-3 states for the manifest. nonce is the request nonce.
singleUseId is the identifier consumed on the first settlement
attempt (MUST-T6-2).
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A party that accepts a Decision Token MUST reject it if the signature
fails, if kid does not match a configured PDP key, if the content
type is not application/cedulon-decision+cbor, if the decoded claim
map does not match the presented claims, or if expiryMs is in the
past (MUST-T6-5).
10. Rail Extract Profile
A verifier checks completeness against a *rail extract*, not against
the issuer's own receipts alone (MUST-T10-7).
10.1. Record schema
The extract body is a JSON document. Each settlement record MUST
contain the following members, under these names:
+=============+=========================================+
| Member | JSON type |
+=============+=========================================+
| ref | string (rail payment reference) |
+-------------+-----------------------------------------+
| amount | string matching 0|[1-9][0-9]* |
+-------------+-----------------------------------------+
| currency | string |
+-------------+-----------------------------------------+
| timestampMs | number (POSIX milliseconds, an integer) |
+-------------+-----------------------------------------+
Table 8
These member names are normative. A rail MAY add members of its own
to a record; it MUST NOT rename the four above. The types above are
stated in JSON terms.
A record MAY carry a beneficiary member (string). A rail that can
resolve a payment reference to the party credited declares it there;
when present, it is compared against the payee of the receipt that
names the same ref, and a difference is reported (beneficiary-
mismatch). Resolving a reference to a beneficiary is a feature of
the rail's own system: this profile does not assume it, and measures
it only when the rail declares it.
10.2. Scope
An extract is scoped to one account identifier, one rail identifier,
and one half-open time window [windowStartMs, windowEndMs). The
signed body is one JSON document with exactly this shape:
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+===============+=========================================+
| Member | JSON type |
+===============+=========================================+
| accountId | string |
+---------------+-----------------------------------------+
| railId | string |
+---------------+-----------------------------------------+
| windowStartMs | number (POSIX milliseconds, an integer) |
+---------------+-----------------------------------------+
| windowEndMs | number (POSIX milliseconds, an integer) |
+---------------+-----------------------------------------+
| clockSkewMs | number (milliseconds, a non-negative |
| | integer; optional; see Section 12) |
+---------------+-----------------------------------------+
| settlements | array of settlement records (schema |
| | above) |
+---------------+-----------------------------------------+
Table 9
All six named members except clockSkewMs MUST be present; a body
missing one, or a record renaming a core member, MUST be refused by
name at both ends - by the signer before it signs and by the verifier
before it checks a signature - so a malformed extract is the same
refusal on both sides rather than a signature verdict. Additional
members beyond these are the rail's to add, as with records.
The integer-valued members - windowStartMs, windowEndMs, each
record's timestampMs, and clockSkewMs - MUST be integers of magnitude
at most 2^53 - 1, the range a JSON number carries exactly, and
clockSkewMs MUST NOT be negative; a value outside those bounds, or a
non-integer, is refused by name in the same way as a missing member.
windowEndMs MUST be greater than windowStartMs: the window is half-
open, so one that does not end after it starts declares no
population, and a body carrying one is refused by name (malformed-
extract-window) in the same way, at both ends.
The body is read as text before it is read as an object. A text in
which any object repeats a member name is refused as json-duplicate-
key at both ends, before parsing and before any signature is checked
(MUST-T4-20, Section 8); a signer that parsed first would sign one of
the two values and an honest verifier could check the other.
clockSkewMs, when present, declares the boundary allowance the
verifier applies at this window's edges during reconciliation
(Section 12); when absent, the profile default of 300000 milliseconds
(five minutes) applies.
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10.3. Authentication
The rail signs Ed25519 [RFC8032] over the canonical encoding of the
scoped body, which is a JSON document and therefore takes the
encoding of Section 8: the signed octets are the UTF-8 octets of the
[RFC8785] encoding of the body above. The signature and the rail's
public key travel beside the body, the signature as base64 and the
key as a SubjectPublicKeyInfo PEM; neither is part of the signed
octets. A verifier MUST obtain the extract from the rail or from a
signature the rail published (MUST-T10-7). A deployment that cannot
do so is running the reconciliation against evidence it did not
obtain independently, and MUST report the guarantee as conditional.
A signature on an extract proves internal consistency, not origin: a
key generated by whoever produced the object verifies against itself.
The verifier therefore MUST obtain the rail's public key out of band
and MUST verify the extract signature against that key (MUST-T10-8).
A key the extract carries is not that key: it is neither the rail's
identity nor a fallback for one the verifier did not obtain. Where
no such key is held, the carried key is the only key present, so the
signature check that runs against it says the extract is internally
consistent and says nothing about who produced it, and the verifier
MUST treat the guarantee as conditional.
Keys are compared as bytes. A verifier MUST compare the pinned key
and the key that signed the extract by their SubjectPublicKeyInfo DER
encoding, not by any text encoding of it, so that the same key
presented in a different envelope still compares equal (MUST-T10-9).
A pinned key the verifier cannot decode is a fault in the verifier's
own configuration, not evidence about the extract, and MUST be
reported as trust-key-unreadable rather than as a key mismatch.
What a verifier emits for an extract it cannot authenticate depends
on whether it stated an expectation. With no pinned key the verifier
has asserted nothing, so the condition is unauthenticated-extract
whatever the extract carries - a signature that verifies against the
carried key establishes internal consistency and not origin, and one
that fails or is refused is not a verdict about a key either. It is
a warning: completeness findings may still be computed, but the
guarantee is *conditional* on the extract being authentic. With a
pinned key the verifier has asserted what it requires, and an extract
that fails to meet it is a failure rather than a caveat; see the
verification algorithm for which finding applies. See Section 15.
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10.4. Scope agreement
An extract declares a window and carries settlement records. The two
MUST agree: a verifier MUST report every settlement record whose
timestampMs falls outside [windowStartMs, windowEndMs) as extract-
scope-mismatch, identified by that record's ref (MUST-T10-10). This
check is about the extract's internal consistency and MUST be
performed whether or not a rail key is pinned.
A verifier that knows which account, rail, and window it is auditing
MUST also check the extract against that expectation and MUST fail
closed when the extract does not cover it (MUST-T10-11). An extract
for another account or rail, or one whose window does not span the
period under audit, cannot support a completeness claim about that
period.
A verifier that has not stated the period under audit MUST emit
unstated-audit-window and MUST treat the guarantee as conditional
(MUST-T10-15), whatever else verifies.
Likewise, a verifier that has not stated the account or the rail
under audit MUST emit unstated-audit-scope and MUST treat the
guarantee as conditional (MUST-T10-18). Where no rail key is pinned
at all, all three axes are equally unstated and unauthenticated-
extract is the condition reported.
A balanced audit under an unconditional guarantee is true of one
account, on one rail, over one window, so a report that carries it
MUST also carry that account, rail and window (MUST-T10-19). A
completeness claim about an account needs one such report per rail
that account can settle on; enumerating those rails is the
deployment's statement.
11. Trust roots
Section 10 states the rule for one object: a signature proves
internal consistency, not origin, so the verifier obtains the rail
key out of band and checks the extract against it, and the key the
extract carries is neither the rail's identity nor a fallback for one
the verifier did not obtain (MUST-T10-8). The same discipline
applies to the issuer: a verifier obtains the public key from an
authenticated channel and rejects a kid that does not match that key
(MUST-T4-8). This section states the verification algorithm, the
separate root inputs, and the error semantics that name a missing or
mismatched pin, for every signed object in the profile.
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+==================+=======================+============+
| Object | Key the verifier pins | Section |
+==================+=======================+============+
| Rail Extract | rail key | Section 10 |
+------------------+-----------------------+------------+
| Spend Receipt, | issuer key | Section |
| epoch checkpoint | | 11.1 |
+------------------+-----------------------+------------+
| Payee | payee key | Section |
| countersignature | | 11.2 |
+------------------+-----------------------+------------+
| Decision Token | the deployment's own | Section |
| | PDP signing key | 11.3 |
+------------------+-----------------------+------------+
| Trade Manifest | publisher key | Section |
| | | 11.4 |
+------------------+-----------------------+------------+
Table 10
Without these roots, a verifier that checks a Spend Receipt against
the key the receipt carries accepts a receipt signed by any key at
all, and a forged receipt can make an unreceipted settlement look
covered.
11.1. The issuer root
A verifier MUST obtain the issuer's public key out of band and MUST
verify Spend Receipt and epoch checkpoint signatures against that
key. A key the object carries is not that key: it establishes no
signer identity and is not a fallback for a pin the verifier does not
hold (MUST-T4-9, MUST-T4-11). Where no issuer key is held, a
signature checked against the key its own object carries establishes
internal consistency and nothing more, which is the state Section 7.3
and the last row of the table below describe. A verifier that holds
no such key and is presented with any Spend Receipt or epoch
checkpoint MUST treat the completeness guarantee as conditional and
SHOULD report the condition; the identifier unauthenticated-issuer is
used for it in this document.
An audit given no receipts and no checkpoints rests on the extract
alone and is not made conditional by this requirement.
Reporting a mismatch is not sufficient on its own. A receipt that
does not answer to the pinned issuer key MUST NOT count as coverage
for the settlement it names, and the settlement MUST still be
reported as uncovered (MUST-T4-10).
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Keys are compared as bytes, by their SubjectPublicKeyInfo DER
encoding, on the same terms as MUST-T10-9. A pinned issuer key the
verifier cannot decode is a fault in its own configuration and MUST
be reported as trust-key-unreadable rather than as a mismatch against
the objects; where no pinned key can be decoded at all, nothing is
attested and the verifier MUST NOT fall back to accepting the keys
the objects carry (MUST-T4-11).
Membership in the attested set follows one rule: the signature
verifies under a pinned issuer key. The kid header routes the check
to a candidate key; the key an object carries beside its signature is
not an identity source, because it travels outside the signed octets
and anyone can rewrite it. Two consequences are stated so that
implementations do not diverge on them. First, an honestly signed
object whose carried key was swapped stays attested: the swap is
reported (carried-key-mismatch, a warning) and MUST NOT move the
object out of the attested set or change the verdict, on the same
reasoning as Section 6.1 - a surface the signature does not cover
must not be able to manufacture a negative result. Second, an object
that claims the pin, by its carried key or its kid, but does not
verify under it is excluded from the attested set and MUST still be
walked and named - for a receipt, receipt-chain-break with a
signature-failed detail - never silently dropped; an object that
neither verifies under the pin nor claims it is issuer-key-mismatch,
excluded, and the settlement it names stays uncovered.
The rule, read out per cell (steps 6 and 8 are the verification
algorithm's):
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+==========+==========+===========================================+
| Claims | Verifies | Result |
| the pin | under | |
| (carried | the pin | |
| key or | | |
| kid) | | |
+==========+==========+===========================================+
| yes | yes | attested; a carried key other than the |
| | | verifying one is carried-key-mismatch, a |
| | | warning, and does not move the receipt |
+----------+----------+-------------------------------------------+
| yes | no | excluded from the attested set; still |
| | | walked and named in step 6 (receipt- |
| | | chain-break, signature-failed detail); |
| | | its settlement stays uncovered in step 8. |
| | | A checkpoint has no chain walk to be |
| | | named in, so it is reported as issuer- |
| | | key-mismatch on this row as well as the |
| | | next, and the window it would have |
| | | covered is reported uncovered |
+----------+----------+-------------------------------------------+
| no | no | issuer-key-mismatch; excluded; its |
| | | settlement stays uncovered in step 8 |
| | | (MUST-T4-9, MUST-T4-10) |
+----------+----------+-------------------------------------------+
| no pin | no pin | no comparison against a key the verifier |
| held | to | holds happens, and the keys the objects |
| | verify | carry are not a fallback for one (MUST- |
| | under | T4-11); each signature is still checked |
| | | against the key its own object carries |
| | | (Section 7.3), which establishes that the |
| | | object is internally consistent and |
| | | nothing about who signed it, so a broken |
| | | signature is still named (receipt-chain- |
| | | break, checkpoint-total-mismatch) while |
| | | two different issuers cannot be told |
| | | apart; receipts are presented-unattested, |
| | | the verifier reports unauthenticated- |
| | | issuer, and accusation-shaped findings |
| | | take the two-branch severity of MUST-T8-9 |
+----------+----------+-------------------------------------------+
Table 11
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A verifier MUST accept an issuer root that is a set of keys rather
than a single key (MUST-T4-12), so that a key rotation mid-window
does not force it off the pin. The same acceptance applies to a
publisher pin, a witness pin, and a rail pin: a verifier MUST accept
each of those roots as a set of keys, so a rotation inside the window
does not force it off the pin.
11.2. The payee root
The optional countersignature in Section 6.1 travels beside the
issuer signature without being covered by it. Anyone holding an
honest receipt can append a countersignature of their own, so a
verifier that checks it against the key carried next to it learns
only that some key signed something.
A countersignature MUST NOT be treated as evidence that the payee
approved the payment unless it verifies against a payee key the
verifier obtained out of band (MUST-T4-13). Without such a key the
verifier SHOULD report the condition and MUST treat the guarantee as
conditional.
Where a verifier has pinned a key for a payee, a settled receipt
naming that payee and carrying no *attributable* countersignature
MUST be reported (MUST-T4-14): a countersignature that failed to
verify, or verified under some other key, is discarded under
Section 6.1 and leaves the expectation open exactly as a missing one
does. The discarded object itself is a warning, never a failure of
the receipt it rode beside; Section 6.1 states the invariant.
11.3. The decision root
A Decision Token is issued by the policy decision point and consumed
by the same deployment. A consumer MUST verify a Decision Token
against its own issuing key and MUST NOT accept one it cannot check
that way (MUST-T6-6).
11.4. The manifest root
A verifier that is presented with a Trade Manifest MUST obtain the
publisher's public key out of band and MUST verify the manifest
signature against that key, not against a key the manifest carries
(MUST-T4-15). A verifier without such a key that is presented with a
Trade Manifest MUST report the completeness guarantee as conditional
and SHOULD report the condition; the identifier unauthenticated-
manifest is used for it in this document. An audit presented with no
Trade Manifest is not made conditional by this requirement.
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A pinned manifest key the verifier cannot decode is a fault in its
own configuration and MUST be reported as trust-key-unreadable rather
than as a mismatch, on the same terms as MUST-T4-11. A manifest that
does not verify against a readable pin MUST be reported as manifest-
key-mismatch and MUST fail the audit.
A verifier presented with a Trade Manifest MUST compare the manifest
hash to the manifestHash of the receipts presented to the audit and
MUST report a manifest that no presented receipt references (MUST-
T4-17); the identifier manifest-covers-no-receipt is used for it in
this document, and the completeness guarantee is conditional. The
comparison runs against those presented receipts, including aborted
ones, and is made before any extract window is applied and before any
issuer key is applied; a hash on an aborted receipt, on a receipt
outside the extract window, or on a receipt no pinned key attests
still counts as a reference. This requirement asks whether any
receipt names the terms, not whether a settlement in the window was
made under them, and not whether the receipt that names them is
attributable, so a forged receipt can silence this warning; the
report it leaves behind is still conditional and still carries the
finding that the receipt answers to no pinned key. This requirement
does not reach the audit presented with no Trade Manifest, which
remains a deployment choice under MUST-T1-2.
Naming a manifest is not obeying one. A verifier presented with a
Trade Manifest MUST compare the amount, the currency and the
settlement time of every receipt that names it against the manifest's
amount, currency and expiry, and MUST report a receipt that departs
from them (MUST-T8-9); the identifier manifest-terms-mismatch is used
for it in this document. Every receipt that names the manifest is
measured, aborted ones included. The time compared is the receipt's
timestampMs, against the boundary MUST-T3-3 states: strictly after
expiresAtMs departs, exactly at it does not. Amount and currency are
compared on the exact-octet terms of MUST-T8-2.
Where a usable issuer key is pinned, the comparison is made over the
receipts that verify under it and the audit fails. Where none is
pinned, the departure is still reported and the audit does not fail
on it alone. An issuer key is usable when the pinned issuer root
holds at least one key the verifier can decode. A pinned root none
of whose keys decode is already trust-key-unreadable and attests
nothing, so the comparison takes the unpinned branch while that
finding stands; the audit has failed on the configuration fault, and
the departure is still reported without becoming a charge no readable
key backs. Only receipts that name the manifest are measured against
it. Under a usable issuer pin, a departure is a finding rather than
a condition on the guarantee.
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A policy decision point presented with a Trade Manifest it cannot
attribute MUST refuse the payment rather than settle and record the
doubt (MUST-T4-16): a settled payment carrying the hash of terms
nobody authorised cannot be withdrawn by reporting it afterwards.
11.5. What the roots do not cover
A verifier that supplies none of these roots is not making an error,
and this document does not require it to. It is making a weaker
statement, and the guarantee it reports must say so. With no issuer
key nothing distinguishes one submitted receipt from another, so
conditions computed across the submitted set - two receipts claiming
one settlement reference, for instance - cannot be attributed to
anyone and are reported as conditions of the submission rather than
as failures of a party; the finding stands, only its attribution
changes.
12. Reconciliation
Completeness is the property that, given an authenticated rail
extract, every settlement in the extract has a matching settled Spend
Receipt, every settled receipt has a matching settlement, receipt and
checkpoint hash chains verify, and checkpoint totals equal the sum of
*settled* receipts in the checkpoint window. If a spend occurred
without a receipt, the missing receipt is itself the evidence (MUST-
T10-2).
The property is stated over a population, and the extract is what
declares it: one account, on one rail, over one window (Section 10).
"Every settlement" means every settlement that extract carried. A
settlement path no presented extract covers is not reconciled and not
found missing - it is outside the population - so the report names
the account, rail and window it was computed over (MUST-T10-19), and
a verifier that stated none of them says so instead (MUST-T10-18).
A checkpoint published with its totals withheld
([CEDULON-CHECKPOINT], Checkpoint claims) cannot contribute the last
of those to the property. It is not a violation of completeness and
it is not a demonstration of it either: the comparison was not made,
and a result that rests on a comparison nobody made is conditional
(MUST-T11-12).
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12.1. Verification algorithm
A verifier MUST perform all of these steps and MUST report every
finding they produce (MUST-T10-1). They are numbered for reference,
not to require an evaluation order: no step short-circuits another,
and an implementation may evaluate them in any order that produces
the same set of findings.
Two data dependencies limit that freedom, because "any order" read
naively would break them. An order that runs a step before the step
it consumes does not produce the same set of findings and is not
permitted.
The first is the index of refs: step 7 builds it, and steps 8 and 9
reconcile it.
The second is the issuer pin. The step that resolves it decides the
*working set*: the attested set - the receipts and checkpoints that
verify under a usable pinned issuer key - or, when no usable key is
pinned, the whole presented set, whose members are presented-
unattested. Every later step that walks receipts consumes the
working set: the indexing and reconciliation in steps 7 through 9 and
the MUST-T8-9 comparison. The chain walk in step 6 consumes the
working set plus one addition named in Section 11.1: a receipt that
claims the pin and fails to verify under it is walked so the break
can be named, and is attested nowhere. A receipt that neither claims
the pin nor verifies under it is reported once (issuer-key-mismatch)
and then excluded, which is what keeps the settlement it names
visible as uncovered (MUST-T4-10); an implementation that let it back
into any of those steps would let a forged receipt cover a
settlement, satisfy a checkpoint count, or invent a terms charge.
Two checks deliberately stay on the presented set whatever any key
says, and MUST NOT acquire the dependency: MUST-T4-17, which asks
whether a manifest was named at all, and the per-receipt defect
checks that ask what a receipt says about itself.
Checkpoint and witness verification consumes that working set and is
specified in [CEDULON-CHECKPOINT] (Verification algorithm), which an
implementation of this audit also implements: a receipt that falls in
no presented checkpoint window, including every receipt when no
checkpoint is presented, fails that document's window-coverage check.
When a step names an identifier in backticks, that identifier SHOULD
be used for the condition in diagnostic output. The normative
requirement is the behaviour: report the condition, identified by the
ref or other handle given in the step. The identifiers are not an
interoperability surface.
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1. Establish the subject of the audit. When an extract is
supplied, the settlement records it carries are the ones
reconciled; a settlement list from any other source MUST NOT be
substituted for them (MUST-T10-12). If the caller supplies both
and they differ, the verifier MUST report that the caller-
supplied list disagrees with the extract, and MUST still
reconcile the extract. The identifier extract-settlement-
mismatch SHOULD be used for this condition in diagnostic output.
2. Verify the extract signature against the out-of-band rail key
(MUST-T10-8, MUST-T10-9). If no key is pinned, the check that
runs is against the key the extract carries, which establishes
internal consistency and not origin; the verifier MUST still
compute it, MUST NOT read it as a statement about who produced
the extract, and MUST treat the completeness guarantee as
conditional (MUST-T10-7). The identifier unauthenticated-
extract SHOULD be used for this condition in diagnostic output,
whatever the extract carries. If a key is pinned and cannot be
decoded, the verifier MUST report that the pinned key is
unreadable. The identifier trust-key-unreadable SHOULD be used
for this condition. If a key is pinned and the signature does
not verify against it, or verifies against a different key, the
verifier MUST report that the extract is not signed by the
pinned key. The identifier extract-key-mismatch SHOULD be used
for this condition. The rows of an extract the pin refused are
not reconciled against the receipts, and no settlement finding
is read out of that document (MUST-T10-20); the identifier
settlement-comparison-skipped SHOULD be used to say that the
comparison did not run. A finding that puts the extract itself
in doubt MUST prevent an unconditional guarantee.
3. Check scope. The verifier MUST report each settlement record
whose timestampMs falls outside the declared window, identified
by that record's ref (MUST-T10-10). When the verifier states an
expected account, rail, or window, it MUST report an extract
that does not cover it (MUST-T10-11). The identifier extract-
scope-mismatch SHOULD be used for both conditions. If the
verifier stated no period, it MUST treat the guarantee as
conditional (MUST-T10-15). The identifier unstated-audit-window
SHOULD be used for this condition. If it stated no account or
no rail, it MUST treat the guarantee as conditional for the same
reason (MUST-T10-18); the identifier unstated-audit-scope SHOULD
be used. Whatever the verdict, the report MUST name the
account, rail and window the extract declared, in every
structure it returns for the audit (MUST-T10-19).
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4. Resolve each Spend Receipt against the issuer root
(Section 11.1) in one pass. Decode the COSE_Sign1; a content
type that is not the receipt type, a decoder bound, or a decoded
claim map that does not match the presented claims is a named
refusal, not a signature verdict (MUST-T4-2, MUST-T4-8). Then
ask one question: does the signature verify under a pinned
issuer key. kid routes the check to a candidate key and carries
no authority of its own; the carried key is not consulted for
membership at all. The resolution table in Section 11.1 reads
the answer out per cell. Every cell there is a named condition
plus a membership decision; no cell is a silent removal. Where
a countersignature is present, Section 11.2 governs what it
establishes (MUST-T4-13, MUST-T4-14). Where a Trade Manifest is
presented, Section 11.4 governs it (MUST-T4-15): with no
publisher key pinned the verifier reports unauthenticated-
manifest and the guarantee is conditional; with a pin that
cannot be read, trust-key-unreadable; with a pin the manifest
does not answer to, manifest-key-mismatch; and with a manifest
that no presented receipt references, manifest-covers-no-receipt
(MUST-T4-17). A receipt that names the manifest but departs
from its amount, currency, expiry or, where the manifest names
one, payee is reported as manifest-terms-mismatch; with a usable
issuer key pinned the comparison runs over the attested receipts
and the departure fails the audit, and with no usable issuer key
it is a warning over the presented receipts and does not by
itself fail the audit (MUST-T8-9). An audit presented with no
Trade Manifest is not made conditional by this step.
5. Scope the receipts. Membership follows the ref binding first: a
receipt whose ref appears on the extract is reconciled against
this extract even when its own timestampMs falls outside the
declared window - the rail has signed that the settlement
belongs to the window, and the receipt follows its settlement.
The timestampMs sieve applies only to receipts the extract does
not name: such a receipt outside the window is not a
completeness failure against this extract (MUST-T10-16);
auditing a longer period requires extracts that cover it. At
the window's edges the declared allowance applies (Section 10):
an unmatched settled receipt within clockSkewMs of windowEndMs,
and an unmatched settlement record within clockSkewMs of
windowStartMs, are reported as boundary-deferred, a warning,
rather than as step 8's completeness findings - two honest
clocks can disagree by less than the allowance, and both
verifiers of an honest edge payment would otherwise reach the
same false accusation (MUST-T10-17). Where the following
window's extract is presented and verifies, a deferred receipt
whose ref appears on it is resolved and not reported, and one
whose ref does not appear hardens into the step 8 finding; a
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deferred settlement record near the opening edge resolves
through this step's ref binding, since the prior window's
receipt that names its ref is reconciled here regardless of
timestamp. The following window's extract closes or hardens
closing-edge deferrals only; an opening-edge record stays
deferred until a receipt in the presented bag names its ref,
whether or not a following extract is presented. In a single-
window audit a deferred record keeps the guarantee conditional.
Receipts remain subject to every other check regardless of
window.
6. Walk the receipts of the working set, together with any receipt
that claims the pin and failed to verify under it
(Section 11.1), in issuer order. Issuer order is the order
induced by the prevReceiptHash chain: the verifier rebuilds the
chain from the links, and the order in which receipts were
presented carries no weight. timestampMs is issuer-asserted and
is not an ordering source. The first prevReceiptHash MUST be
null. Each later prevReceiptHash MUST equal receiptHash of the
previous receipt. A miss, and a receipt the links cannot place,
MUST be reported as a break in the receipt chain. The
identifier receipt-chain-break SHOULD be used for this
condition. An issuer stream that does not chain its receipts
(SHOULD-T4-5) is therefore reported as a break from its second
receipt on: the SHOULD states what an issuer owes, and this step
states what a verifier does with a stream that did not.
7. Index the settled receipts of the working set and the extract
records by ref. A ref that appears more than once on either
side MUST be reported as a repeated reference (MUST-T10-6). The
identifier duplicate-ref SHOULD be used for this condition.
8. For each ref that appears exactly once on each side, require a
one-to-one match on ref AND amount AND currency (MUST-T10-1),
compared as exact octets on the terms of MUST-T8-2; step 9's
aggregation is the only place this algorithm reads an amount as
a number. Amount or currency mismatch MUST be reported as a
settlement that does not match its receipt, identified by that
ref. The identifier settlement-mismatch SHOULD be used for this
condition. A settlement with no receipt MUST be reported as
lacking a receipt, identified by its ref (MUST-T10-2). The
identifier settlement-without-receipt SHOULD be used for this
condition. A settled receipt with no extract row MUST be
reported as a completeness failure (MUST-T10-3). The identifier
receipt-without-settlement SHOULD be used for this condition. A
settled receipt with a null rail ref MUST be reported as settled
without a rail reference; this check asks what a receipt says
about itself and runs over the presented receipts, attested or
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not. The identifier settled-without-ref SHOULD be used for this
condition. Where a settlement record declares a beneficiary
(Section 10), it MUST be compared against the matched receipt's
payee as exact octets; a difference is beneficiary-mismatch and
fails the audit. Where neither the manifest names a payee nor
any settlement record declares a beneficiary, the report MUST
carry counterparty-unbound, a scope record: ref, amount and
currency closed against the payer's account extract, and the
counterparty's identity was not bound. It is a statement of
what the evidence did not cover, not a doubt about what it did,
so it does not move the verdict and does not by itself make the
guarantee conditional.
9. A ref already reported as repeating MUST still be reconciled by
amount rather than dropped from the comparison (MUST-T10-13).
For each currency under that ref, compare the total settled
against the total receipted. A settled total that exceeds the
receipted total MUST be reported as a settlement lacking a
receipt, and the finding MUST state the unaccounted amount. The
identifier settlement-without-receipt SHOULD be used for this
condition. A settled total that is less than the receipted
total MUST be reported as a settlement that does not match its
receipt, identified by that ref. The identifier settlement-
mismatch SHOULD be used for this condition. An amount on that
repeating ref that cannot be parsed as an integer MUST be
reported without abandoning the audit; the identifier malformed-
amount SHOULD be used for this condition. A verifier MUST still
report findings for the remaining records.
10. Aborted receipts are not matched to extract rows and are not
added to totals.
11. If any finding remains that is not a warning (a warning is a
condition that only makes the completeness guarantee
conditional), the audit MUST fail (MUST-T10-4).
12.2. Finding codes
The identifiers are listed in Appendix B. They are for diagnostic
output. They are not an interoperability surface. A finding object
that can be carried on the wire is outside the scope of this document
and may be defined later. Two implementations interoperate when they
accept the same inputs and fail or warn on the same conditions, not
when they print the same strings.
A condition that makes the audit fail is a finding. A condition that
only makes the completeness guarantee conditional is a warning.
Warnings MUST still appear in operator-facing output (MUST-T10-14).
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A finding that puts the extract itself in doubt (extract-key-
mismatch, trust-key-unreadable, extract-scope-mismatch, or extract-
settlement-mismatch) MUST also prevent an unconditional guarantee,
not merely fail the audit. A finding that puts a presented Trade
Manifest in doubt (manifest-key-mismatch, or trust-key-unreadable on
the manifest pin) does the same.
An unconditional guarantee therefore requires all of: an extract, a
pinned rail key the extract's signature verifies against, a stated
period the extract covers, an issuer root for whatever receipts and
checkpoints are presented, a manifest root for whatever Trade
Manifest is presented, no finding that puts the extract in doubt, and
no warning that withholds part of the comparison. A checkpoint whose
totals were signed as withheld (checkpoint-totals-redacted) removes a
comparison the guarantee rests on, and a presented checkpoint a
supplied witness does not hold (checkpoint-not-anchored) leaves part
of the chain unwitnessed. Either one makes the result conditional.
Anything less than the whole list is conditional, and the report MUST
say so.
An implementation MUST make the guarantee and any warnings visible in
whatever human-readable audit report it produces under this document,
not only in a returned structure (MUST-T10-14). A report that says
the books balance while withholding that the balance is conditional
invites the reader to take a conditional result for an unconditional
one.
Checkpoints SHOULD be registered with a Transparency Service (SHOULD-
T11-5). A test deployment MAY use an in-process append-only log as
the witness (MAY-T11-6). Cedulon still MUST NOT take custody.
The guarantee named above is about completeness against the extract,
which is the subject of T10. It is not a claim that no checkpoint
was suppressed. Suppression is the subject of T11, and a report MUST
NOT be read as settling it when no witness was consulted: with no
witness receipts, the presented chain is self-consistent by
construction and says nothing about what it left out (MUST-T11-9). A
verifier that consulted a witness and found every presented
checkpoint recorded, with nothing recorded that was not presented,
has discharged T11 for the period those receipts cover, and for no
longer.
13. Policy Semantics
Policy is default deny. The engine understands three families of
rule:
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* *Limit:* maximum amount per payment; maximum cumulative amount per
window (MUST-T2-2).
* *Velocity:* maximum number of allowed payments per window (MUST-
T2-1).
* *Scope:* optional allow-lists for payee, currency, and tool name.
Fail-closed: missing engine, crash, or exception yields deny (MUST-
T2-3). Implementations SHOULD emit stable reason codes (SHOULD-
T2-5). Decision tokens SHOULD expire after a short time-to-live
(TTL) (SHOULD-T6-3).
The agent-facing spend interface MUST invoke the PDP and MUST NOT
expose a parallel ungated rail call to the model (MUST-T5-1).
One boundary is stated here rather than left to be inferred. In the
retrospective audit, "allowed by policy" is the Receipt Issuer's
signed assertion: the spend passed the issuer's gate under the
policyHash the receipt names. The Decision Token is consumed at the
gate, and the verification algorithm never sees it; the audit does
not independently re-verify the PDP's allow. The completeness side
of the audit has an independent leg - the rail extract - and the
policy side deliberately does not: that is a trust boundary of this
profile, not an oversight. A deployment that wants the policy answer
to be independently verifiable needs a receipt-to-token binding,
which this document does not define; adding it would change what a
receipt carries.
14. Privacy Considerations
A public transparency encoding MUST support omitting or hashing payer
and payee identifiers and MUST support amount redaction or bucket
encoding (MUST-T9-1). Implementations MUST NOT write government-ID
numbers, the Primary Account Number (PAN) of a payment instrument, or
street address into a public statement (MUST-T9-2). Default public
anchors SHOULD publish policyHash, manifestHash, receiptHash, and
timestampMs rather than full claims (SHOULD-T9-3). A private auditor
MAY receive an unredacted receipt out of band (MAY-T9-4).
The paragraph above counts receipt fields. A checkpoint publishes
something a receipt does not: a per-currency total for a whole
window, which discloses trading volume even when every individual
receipt is redacted (MUST-T9-5).
The rule is the one [CEDULON-CHECKPOINT] defines and Section 12
applies: totals MAY be withheld by signing it as null (MUST-T11-12),
and only that form counts as a redaction (MUST-T11-13). The
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structural claims are not redactable, because a verifier that cannot
read the window or the chain head cannot check anything at all, and a
checkpoint that hid them would be indistinguishable from a broken
one.
When totals are withheld, a verifier that cannot recompute them says
so, and the completeness guarantee for that window is conditional. A
deployment that wants an unconditional result publishes the totals; a
deployment that wants the volume private accepts a conditional one.
What a deployment MUST NOT do is obtain the unconditional result
while withholding the evidence for it.
15. Security Considerations
This section is authoritative for the protocol requirements in this
document. The threat narratives in [CEDULON-THREATS] are informative
and do not override it.
Requirement identifiers take the form KEYWORD-Tn-k, where KEYWORD is
MUST, SHOULD, or MAY, n is the threat number in this section, and k
is a sequence number within that threat. MUST-T8-custody is the
custody prohibition under T8. The tables below define the
requirement text those citations refer to.
15.1. T1: Prompt injection leads to unauthorized spend
An attacker plants instructions in tool output, a web page, or a
retrieved document. The agent then calls a spend tool outside the
principal's intent. Narrative: [CEDULON-THREATS].
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+=============+=============================================+
| ID | Requirement |
+=============+=============================================+
| MUST-T1-1 | The PDP MUST decide from structured request |
| | fields and stored policy, not from model- |
| | generated prose. |
+-------------+---------------------------------------------+
| MUST-T1-2 | A spend that is not bound to a verified |
| | Trade Manifest MUST be marked noManifest on |
| | the Spend Receipt and MUST still be subject |
| | to limit, velocity, and scope policy. |
+-------------+---------------------------------------------+
| SHOULD-T1-3 | Hosts SHOULD require a human confirmation |
| | channel for first-use payees. |
+-------------+---------------------------------------------+
| MAY-T1-4 | An implementation MAY refuse all noManifest |
| | spend. |
+-------------+---------------------------------------------+
Table 12
15.2. T2: Runaway agent (loop spend)
A stuck tool loop or recursive planner issues many payments.
Velocity and cumulative-limit counters live in the PDP, fail-closed.
Narrative: [CEDULON-THREATS].
+=============+==================================================+
| ID | Requirement |
+=============+==================================================+
| MUST-T2-1 | Policy MUST express a maximum payment count per |
| | configured time window (velocity). |
+-------------+--------------------------------------------------+
| MUST-T2-2 | Policy MUST express a maximum amount per payment |
| | and a maximum cumulative amount per window. |
+-------------+--------------------------------------------------+
| MUST-T2-3 | If the PDP is unreachable, uninitialized, or |
| | throws during evaluation, the spend MUST be |
| | denied (fail-closed, default deny). |
+-------------+--------------------------------------------------+
| MUST-T2-4 | A denied attempt MUST NOT increment the allowed- |
| | spend counters as if it had succeeded. |
+-------------+--------------------------------------------------+
| SHOULD-T2-5 | Implementations SHOULD emit a stable reason code |
| | for velocity and limit denials. |
+-------------+--------------------------------------------------+
Table 13
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15.3. T3: Replay of payment authority
An observer replays a signed payment payload, mandate, or Cedulon
decision token. Every gated spend carries a unique nonce; manifests
expire; tokens are single-use. Narrative: [CEDULON-THREATS].
+=============+==================================================+
| ID | Requirement |
+=============+==================================================+
| MUST-T3-1 | Every spend attempt that the PDP allows MUST |
| | include a nonce that the implementation has not |
| | accepted before. |
+-------------+--------------------------------------------------+
| MUST-T3-2 | A second attempt that reuses a nonce MUST be |
| | denied. |
+-------------+--------------------------------------------------+
| MUST-T3-3 | A Trade Manifest MUST carry an expiry; a spend |
| | against an expired manifest MUST be denied. The |
| | manifest is expired when the settlement time is |
| | strictly greater than expiresAtMs; a settlement |
| | at exactly expiresAtMs is within the manifest. |
+-------------+--------------------------------------------------+
| MUST-T3-4 | A PDP allow decision MUST be bound to the |
| | SHA-256 of the canonical encoding of the request |
| | fields it evaluated, as stated in Section 8.1, |
| | and MUST be single-use. |
+-------------+--------------------------------------------------+
| SHOULD-T3-5 | Nonce stores SHOULD persist across process |
| | restart when the deployment is not a test |
| | fixture. |
+-------------+--------------------------------------------------+
Table 14
15.4. T4: Receipt forgery or repudiation
A party alters a receipt, invents a receipt, or denies a real spend.
Receipts are signed; verification covers the signed bytes; a hash
chain links them. Narrative: [CEDULON-THREATS].
+=============+=====================================================+
| ID | Requirement |
+=============+=====================================================+
| MUST-T4-1 | A Spend Receipt MUST be signed by the Receipt |
| | Issuer over the deterministic CBOR encoding of |
| | its claims, as profiled in Section 7. The phrase |
| | "canonical encoding" is reserved for JSON |
| | documents (Section 8). |
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+-------------+-----------------------------------------------------+
| MUST-T4-2 | Verifiers MUST reject a receipt whose signature |
| | does not validate or whose canonical bytes do not |
| | match the signed payload. |
+-------------+-----------------------------------------------------+
| MUST-T4-3 | A Spend Receipt MUST include payer, payee, |
| | amount, currency, policyHash, timestampMs, and |
| | nonce. |
+-------------+-----------------------------------------------------+
| MUST-T4-4 | A Spend Receipt MUST include manifestHash or an |
| | explicit noManifest flag, never an ambiguous |
| | empty hash. Empty optional values are CBOR null; |
| | labels are never absent. |
+-------------+-----------------------------------------------------+
| SHOULD-T4-5 | Receipts SHOULD form a hash chain |
| | (prevReceiptHash) so omission is detectable |
| | within one issuer stream. |
+-------------+-----------------------------------------------------+
| MAY-T4-6 | Parties MAY register the signed receipt as a |
| | SCITT statement to obtain a COSE receipt. |
+-------------+-----------------------------------------------------+
| MUST-T4-7 | A Spend Receipt MUST include outcome (settled or |
| | aborted). A settled receipt MUST have a non-null |
| | rail ref. Aborted receipts MUST NOT enter |
| | checkpoint totals. |
+-------------+-----------------------------------------------------+
| MUST-T4-8 | COSE_Sign1 protected headers MUST use alg -19 |
| | (Ed25519), a mandatory kid, and a payload- |
| | specific content type. Verifiers MUST reject a |
| | kid that does not match the configured issuer |
| | key. |
+-------------+-----------------------------------------------------+
| MUST-T4-9 | A verifier MUST obtain the issuer public key out |
| | of band and MUST verify Spend Receipt and epoch |
| | checkpoint signatures against that key. A key |
| | carried by the object MUST NOT be treated as the |
| | signer's identity and MUST NOT be used as a |
| | fallback where no key was obtained (MUST-T4-11). |
| | A verifier without such a key that is presented |
| | with any Spend Receipt or epoch checkpoint MUST |
| | report the completeness guarantee as conditional. |
| | An audit presented with neither rests on the |
| | extract alone and is not made conditional by this |
| | requirement. |
+-------------+-----------------------------------------------------+
| MUST-T4-10 | A receipt that does not verify against the pinned |
| | issuer key MUST NOT count as coverage for the |
| | settlement it names, and that settlement MUST |
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| | still be reported as uncovered. Reporting the |
| | mismatch is not sufficient on its own. |
+-------------+-----------------------------------------------------+
| MUST-T4-11 | Pinned issuer keys MUST be compared by |
| | SubjectPublicKeyInfo DER encoding. A pinned key |
| | that cannot be decoded MUST be reported as a |
| | verifier configuration fault rather than as a |
| | mismatch, and where no pinned key decodes, the |
| | verifier MUST NOT fall back to the keys the |
| | objects carry. |
+-------------+-----------------------------------------------------+
| MUST-T4-12 | A verifier MUST accept an issuer, publisher, |
| | witness, or rail root comprising more than one |
| | key, so that a key rotation inside the audited |
| | window does not require it to abandon pinning. |
+-------------+-----------------------------------------------------+
| MUST-T4-13 | A payee countersignature MUST NOT be treated as |
| | evidence of payee approval unless it verifies |
| | against a payee key the verifier obtained out of |
| | band. |
+-------------+-----------------------------------------------------+
| MUST-T4-14 | Where a verifier has pinned a key for a payee, a |
| | settled receipt naming that payee and carrying no |
| | attributable countersignature MUST be reported. |
+-------------+-----------------------------------------------------+
| MUST-T4-15 | A verifier that is presented with a Trade |
| | Manifest MUST obtain the publisher public key out |
| | of band and MUST verify the manifest signature |
| | against that key, not against a key the manifest |
| | carries. A pin that cannot be read MUST be |
| | reported as trust-key-unreadable; a readable pin |
| | the manifest does not answer to MUST be reported |
| | as manifest-key-mismatch and MUST fail the audit. |
| | A verifier without such a key that is presented |
| | with a Trade Manifest MUST report the |
| | completeness guarantee as conditional. An audit |
| | presented with no Trade Manifest is not made |
| | conditional by this requirement. |
+-------------+-----------------------------------------------------+
| MUST-T4-16 | A policy decision point presented with a Trade |
| | Manifest it cannot verify against a key supplied |
| | out of band MUST refuse the payment. |
+-------------+-----------------------------------------------------+
| MUST-T4-17 | A verifier presented with a Trade Manifest MUST |
| | compare the manifest hash against the |
| | manifestHash of the receipts presented to the |
| | audit, including aborted ones, before any extract |
| | window is applied and before any issuer key is |
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| | applied, and MUST report a presented manifest |
| | that no presented receipt references. An audit |
| | presented with no Trade Manifest is not made |
| | conditional by this requirement. |
+-------------+-----------------------------------------------------+
| MUST-T4-18 | A decoder MUST refuse a CBOR map that carries a |
| | duplicate encoded key. |
+-------------+-----------------------------------------------------+
| MUST-T4-19 | A decoder MUST impose a bound on encoded size, |
| | nesting depth, and the number of elements it will |
| | decode from an audit input, and MUST refuse an |
| | input that exceeds a bound with a named refusal |
| | rather than by exhausting memory or the stack. |
| | It SHOULD document the bounds it applies. This |
| | document fixes no numbers. |
+-------------+-----------------------------------------------------+
| MUST-T4-20 | A verifier that receives a JSON document as text |
| | MUST refuse a text in which any object repeats a |
| | member name, by name (json-duplicate-key), before |
| | parsing it. A verifier handed an object rather |
| | than text cannot apply this rule and MUST NOT |
| | report that it did. |
+-------------+-----------------------------------------------------+
| MUST-T4-21 | A decoder MUST refuse a COSE_Sign1 message whose |
| | unprotected header is not an empty map, by name |
| | (cose-sign1-unprotected), rather than verifying |
| | the signature and ignoring the header. |
+-------------+-----------------------------------------------------+
Table 15
15.5. T5: Policy bypass via direct rail access
The agent or an attacker calls the rail without the PDP. The only
payment function is the adapter that calls the PDP first. Narrative:
[CEDULON-THREATS].
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+=============+==========================================+
| ID | Requirement |
+=============+==========================================+
| MUST-T5-1 | The agent-facing spend interface MUST |
| | invoke the PDP and MUST NOT expose a |
| | parallel ungated rail call to the model. |
+-------------+------------------------------------------+
| MUST-T5-2 | Rail credentials, wallet handles, and |
| | facilitator tokens MUST NOT be placed in |
| | tool results or prompts. |
+-------------+------------------------------------------+
| SHOULD-T5-3 | Hosts SHOULD run the PDP and signing |
| | keys in a process the model runtime |
| | cannot write. |
+-------------+------------------------------------------+
| MAY-T5-4 | A deployment MAY use OS or hardware |
| | isolation between the model and the PDP. |
+-------------+------------------------------------------+
Table 16
15.6. T6: Time-of-check to time-of-use (TOCTOU) between policy check
and payment
An allow is computed; the request is then swapped before the rail
sees it. Settlement pays only the exact fields hashed into the
single-use decision. Narrative: [CEDULON-THREATS].
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+=============+===================================================+
| ID | Requirement |
+=============+===================================================+
| MUST-T6-1 | Payment settlement MUST use the same six |
| | requestHash fields the PDP evaluated: amount, |
| | currency, payee, tool, nonce, and manifestHash. |
+-------------+---------------------------------------------------+
| MUST-T6-2 | An allow decision MUST be consumed on the first |
| | settlement attempt, success or fail-closed abort, |
| | and MUST NOT authorize a later different request. |
+-------------+---------------------------------------------------+
| SHOULD-T6-3 | Implementations SHOULD treat a decision older |
| | than a short TTL as expired. |
+-------------+---------------------------------------------------+
| MUST-T6-4 | An allow Decision Token MUST be COSE_Sign1 with |
| | CWT private-use labels -70301..-70305 |
| | (requestHash, policyHash, expiryMs, nonce, |
| | singleUseId) and content type application/ |
| | cedulon-decision+cbor. |
+-------------+---------------------------------------------------+
| MUST-T6-5 | A party that accepts a Decision Token MUST reject |
| | a failed signature, a kid or content-type |
| | mismatch, a claim-map mismatch, or an expired |
| | expiryMs. The token is expired when the |
| | evaluation time is strictly greater than |
| | expiryMs; at exactly expiryMs it is not. |
+-------------+---------------------------------------------------+
| MUST-T6-6 | A consumer of a Decision Token MUST verify it |
| | against its own issuing key and MUST NOT accept a |
| | token it cannot check that way. |
+-------------+---------------------------------------------------+
| MUST-T6-7 | A party that records a settlement under a |
| | Decision Token MUST refuse it when that |
| | settlement's timestampMs is strictly greater than |
| | the token's expiryMs. At exactly expiryMs the |
| | settlement remains inside the token's authority; |
| | the boundary is the one MUST-T6-5 states. |
+-------------+---------------------------------------------------+
Table 17
A later verifier cannot make this comparison. Decision Tokens are
not among the inputs Section 12.1 enumerates: the extract, the
receipts, the manifests, the checkpoints, and the witness receipts.
The rule is written on the party that can apply it. Verification
does not repeat it.
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MUST-T6-7 does not let a later verifier detect a settlement that
predates its decision. That would require carrying the decision's
issuance time on the token and binding the receipt to it, which this
document does not define. MUST-T6-4 names the same five labels.
15.7. T7: Signing-key leakage
Keys leak from disk, logs, or a prompt. Forged manifests or receipts
follow. Narrative: [CEDULON-THREATS].
+=============+==============================================+
| ID | Requirement |
+=============+==============================================+
| MUST-T7-1 | Secret key material MUST NOT appear in |
| | receipts, checkpoints, manifests, decision |
| | tokens, logs, or example output. |
+-------------+----------------------------------------------+
| MUST-T7-2 | Example and test keys MUST be generated at |
| | runtime or stored as clearly fake fixtures, |
| | never as production secrets. |
+-------------+----------------------------------------------+
| SHOULD-T7-3 | Production deployments SHOULD use a hardware |
| | security module (HSM) or operating-system |
| | key store and SHOULD rotate keys. |
+-------------+----------------------------------------------+
| MAY-T7-4 | Implementations MAY encrypt keys at rest. |
+-------------+----------------------------------------------+
| MUST-T7-5 | An implementation that stores a signing key |
| | in the clear MUST report the protection it |
| | actually obtained, measured from the stored |
| | object rather than derived from the |
| | platform. |
+-------------+----------------------------------------------+
| MUST-T7-6 | A writable directory anywhere on the path to |
| | a stored signing key makes the file |
| | permission moot, and a symbolic link on that |
| | path hands the destination to whoever placed |
| | it. An implementation MUST refuse both |
| | rather than report the key as protected. |
+-------------+----------------------------------------------+
Table 18
15.8. T8: Counterparty price gouging or defective delivery
The payee ships a different artifact, or the price exceeds the signed
offer. The Trade Manifest binds price and an acceptance-criteria
hash before payment. Narrative: [CEDULON-THREATS].
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+=================+=================================================+
| ID | Requirement |
+=================+=================================================+
| MUST-T8-1 | A Trade Manifest MUST bind goods or service |
| | description, price, currency, acceptance- |
| | criteria hash, cancel condition, and expiry. |
+-----------------+-------------------------------------------------+
| MUST-T8-2 | A spend bound to a manifest MUST be denied if |
| | the requested amount or currency differs from |
| | the manifest. Amount and currency are |
| | compared as the exact octets of their text |
| | strings: no case folding, no Unicode |
| | normalisation, no numeric reinterpretation. |
+-----------------+-------------------------------------------------+
| MUST-T8-3 | If delivery bytes do not hash to the |
| | acceptance-criteria hash, the implementation |
| | MUST be able to produce a Dispute Evidence |
| | Bundle containing the manifest, the spend |
| | receipt, and the delivery hash. |
+-----------------+-------------------------------------------------+
| MUST-T8-4 | The Dispute Evidence Bundle MUST NOT be |
| | described as an arbitral award or escrow |
| | release. |
+-----------------+-------------------------------------------------+
| MUST-T8-7 | manifestHash MUST be the SHA-256 of the signed |
| | Trade Manifest COSE bytes and MUST NOT include |
| | the issuer public key encoding. |
+-----------------+-------------------------------------------------+
| SHOULD-T8-5 | Manifests SHOULD reference an AP2 mandate hash |
| | when one exists. |
+-----------------+-------------------------------------------------+
| MAY-T8-6 | Parties MAY add an optional escrow actor as a |
| | third-party role interface; an implementation |
| | of this specification MUST NOT take custody |
| | (MUST-T8-custody). |
+-----------------+-------------------------------------------------+
| MUST-T8-custody | Implementations of this specification MUST NOT |
| | take custody of funds or operate escrow. |
+-----------------+-------------------------------------------------+
| MUST-T8-8 | If a payee countersignature is present, a |
| | verifier MUST reject it when the signature |
| | fails, when kid or content type does not match |
| | the configured payee key, or when the |
| | receiptCose value (label -70401) is not the |
| | issuer COSE_Sign1 bytes. |
+-----------------+-------------------------------------------------+
| MUST-T8-9 | A verifier presented with a Trade Manifest |
| | MUST compare the amount, currency and |
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| | settlement time of every receipt that names |
| | it, aborted ones included, against the |
| | manifest amount, currency and expiry - amount |
| | and currency on the exact-octet terms of MUST- |
| | T8-2, time on the boundary of MUST-T3-3, and, |
| | where the manifest names a payee, the receipt |
| | payee on the same exact-octet terms - and MUST |
| | report a receipt that departs from them. |
| | Where a usable issuer key is pinned (a pinned |
| | issuer root at least one of whose keys the |
| | verifier can decode), the comparison is made |
| | over the receipts that verify under it and a |
| | departure MUST fail the audit. Where no |
| | usable issuer key is pinned, the departure |
| | MUST still be reported and MUST NOT by itself |
| | fail the audit. Receipts that do not name the |
| | manifest are not measured against it. A Trade |
| | Manifest that a stated publisher pin refuses |
| | is not terms for this purpose: where the |
| | verifier reports manifest-key-mismatch, it |
| | MUST NOT read a charge out of that document's |
| | body, neither this comparison nor the |
| | acceptance-hash comparison of Section 6.1. |
+-----------------+-------------------------------------------------+
| MAY-T8-10 | A payee MAY attach a detached COSE_Sign1 |
| | countersignature over the issuer receipt |
| | bytes. Absence MUST NOT invalidate the issuer |
| | receipt. |
+-----------------+-------------------------------------------------+
| MAY-T8-11 | An attributable countersignature MAY carry |
| | deliveredHash. When present and the verifier |
| | holds the Trade Manifest, the verifier MUST |
| | compare it against acceptanceCriteriaHash as |
| | exact octets and MUST report a mismatch as a |
| | failing finding (delivery-mismatch). A |
| | deliveredHash on an unattributable |
| | countersignature MUST be discarded with it. |
+-----------------+-------------------------------------------------+
Table 19
15.9. Optional escrow role
Parties MAY name an escrow actor in a Trade Manifest as a third-party
role that holds funds under rules outside this protocol (MAY-T8-6).
Implementations of this specification MUST NOT take custody or
operate escrow (MUST-T8-custody).
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15.10. T9: Personally identifiable information (PII) leakage into the
transparency log
A public receipt or transparency statement carries names, addresses,
or full amounts that should stay private. Log-facing encodings offer
redaction. See also Section 14. Narrative: [CEDULON-THREATS].
+=============+===================================================+
| ID | Requirement |
+=============+===================================================+
| MUST-T9-1 | A transparency encoding MUST support omitting or |
| | hashing payer/payee identifiers and MUST support |
| | amount redaction or range/bucket encoding. |
+-------------+---------------------------------------------------+
| MUST-T9-2 | Implementations MUST NOT write raw government-ID, |
| | payment-instrument PAN, or street address fields |
| | into a public transparency statement. |
+-------------+---------------------------------------------------+
| SHOULD-T9-3 | Default public anchors SHOULD publish policyHash, |
| | manifestHash, receiptHash, and timestamp rather |
| | than full claim sets. |
+-------------+---------------------------------------------------+
| MAY-T9-4 | A private auditor MAY receive an unredacted |
| | receipt out of band. |
+-------------+---------------------------------------------------+
| MUST-T9-5 | A checkpoint discloses a per-currency window |
| | total, which the receipt-field rules above do not |
| | cover. Withholding it is governed by MUST-T11-12 |
| | and MUST-T11-13: null in the signed payload, and |
| | no other form of redaction honoured. |
+-------------+---------------------------------------------------+
Table 20
15.11. T10: Secret spend via rail bypass
An operator, leaked credential, or a second binary can settle on the
rail and omit the Receipt Issuer. Completeness reconciles the
extract to the receipts. See Section 12. Narrative:
[CEDULON-THREATS].
+==============+=================================================+
| ID | Requirement |
+==============+=================================================+
| MUST-T10-1 | A verifier MUST match each extract settlement |
| | to a settled receipt on ref AND amount AND |
| | currency. An audit presented with no extract, |
| | no receipts and no checkpoints reports no |
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| | completeness finding. It is not thereby |
| | unconditional, and the warnings for the roots |
| | it was not given still apply. |
+--------------+-------------------------------------------------+
| MUST-T10-2 | A settlement with no matching receipt MUST be |
| | reported as a completeness failure identified |
| | by that settlement ref. |
+--------------+-------------------------------------------------+
| MUST-T10-3 | A settled Spend Receipt whose x402PaymentRef is |
| | not on the extract MUST be reported as a |
| | completeness failure. |
+--------------+-------------------------------------------------+
| MUST-T10-4 | An audit that has any fail-severity |
| | completeness finding MUST fail. |
+--------------+-------------------------------------------------+
| SHOULD-T10-5 | Hosts SHOULD still apply T5 (no ungated rail in |
| | the model process). Completeness does not |
| | replace prevention. |
+--------------+-------------------------------------------------+
| MUST-T10-6 | A ref that appears more than once among settled |
| | receipts or among extract rows MUST be reported |
| | as duplicate-ref. |
+--------------+-------------------------------------------------+
| MUST-T10-7 | A verifier MUST obtain the extract from the |
| | rail or from a rail signature. With no pinned |
| | rail key the extract MUST be reported as |
| | unauthenticated-extract, whatever it carries, |
| | and the completeness guarantee is conditional. |
| | With a pinned key, see MUST-T10-8: the extract |
| | MUST fail closed rather than warn. |
+--------------+-------------------------------------------------+
| MUST-T10-8 | A verifier MUST obtain the rail public key out |
| | of band and MUST verify the extract signature |
| | against that key. A key the extract carries |
| | MUST NOT be treated as the rail's identity and |
| | MUST NOT stand in for a key the verifier did |
| | not obtain. Without such a key the guarantee |
| | is conditional and the condition is reported as |
| | unauthenticated-extract. |
+--------------+-------------------------------------------------+
| MUST-T10-9 | Keys MUST be compared by SubjectPublicKeyInfo |
| | DER encoding rather than by any text encoding. |
| | A pinned key that cannot be decoded MUST be |
| | reported as trust-key-unreadable, not as a key |
| | mismatch. |
+--------------+-------------------------------------------------+
| MUST-T10-10 | Every settlement record whose timestampMs falls |
| | outside the extract's declared window MUST be |
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| | reported as extract-scope-mismatch, identified |
| | by that record's ref. This check MUST run |
| | whether or not a key is pinned. |
+--------------+-------------------------------------------------+
| MUST-T10-11 | When the verifier states an expected account, |
| | rail, or window, an extract that does not cover |
| | it MUST fail closed as extract-scope-mismatch. |
+--------------+-------------------------------------------------+
| MUST-T10-12 | When an extract is supplied, the records it |
| | carries are the subject of reconciliation. A |
| | settlement list from another source MUST NOT be |
| | substituted; a disagreeing list MUST be |
| | reported as extract-settlement-mismatch. |
+--------------+-------------------------------------------------+
| MUST-T10-13 | A ref reported as duplicate-ref MUST still be |
| | reconciled by aggregate amount per currency, |
| | and a shortfall MUST state the unaccounted |
| | amount. An unparseable amount MUST be reported |
| | as malformed-amount without aborting the audit. |
+--------------+-------------------------------------------------+
| MUST-T10-14 | An implementation MUST surface the guarantee |
| | and any warnings in any human-readable audit |
| | report it produces, not only in a returned |
| | structure. |
+--------------+-------------------------------------------------+
| MUST-T10-15 | A verifier that supplies a rail pin but has not |
| | stated the period under audit MUST emit |
| | unstated-audit-window and MUST treat the |
| | guarantee as conditional; with no rail pin at |
| | all the condition reported is unauthenticated- |
| | extract. |
+--------------+-------------------------------------------------+
| MUST-T10-16 | When an extract is supplied, a receipt whose |
| | ref appears on it is reconciled against it |
| | regardless of its own timestampMs; the window |
| | sieve applies only to receipts the extract does |
| | not name, and such a receipt outside the window |
| | MUST NOT be reported as a completeness failure |
| | against that extract. |
+--------------+-------------------------------------------------+
| MUST-T10-17 | An unmatched settled receipt within the |
| | declared clockSkewMs of windowEndMs, and an |
| | unmatched settlement record within it of |
| | windowStartMs, MUST be reported as boundary- |
| | deferred, a warning, rather than as a |
| | completeness failure. A closing-edge deferral |
| | resolves against the following window's extract |
| | and hardens into the completeness finding when |
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| | that extract is presented and does not name the |
| | ref; an opening-edge deferral resolves only |
| | against a receipt in the presented bag that |
| | names its ref, and a following extract does not |
| | harden it. Absent a declared clockSkewMs, the |
| | profile default of 300000 milliseconds applies. |
+--------------+-------------------------------------------------+
| MUST-T10-18 | A verifier that supplies a rail pin but has not |
| | stated the account or the rail under audit MUST |
| | emit unstated-audit-scope and MUST treat the |
| | guarantee as conditional; with no rail pin at |
| | all the condition reported is unauthenticated- |
| | extract. |
+--------------+-------------------------------------------------+
| MUST-T10-19 | A report MUST name the account, rail and window |
| | the extract declared, in the printed report, in |
| | the finding object it returns, and in every |
| | other structure the implementation returns for |
| | that audit, a tool result or an export |
| | included. Where no extract was presented there |
| | is no declared population, and the structure |
| | names none. |
+--------------+-------------------------------------------------+
| MUST-T10-20 | Where a stated rail pin refuses the presented |
| | extract and the verifier reports extract-key- |
| | mismatch, the verifier MUST NOT read a |
| | settlement finding out of that document's body: |
| | not a mismatch against a receipt, not money |
| | reported as unaccounted for, and not a receipt |
| | left unmatched by rows the refused document |
| | omits. The verifier MUST report settlement- |
| | comparison-skipped in the same result. A |
| | pinned key the verifier cannot decode is trust- |
| | key-unreadable and is not a refusal of the |
| | document, so it does not reach this |
| | requirement. |
+--------------+-------------------------------------------------+
Table 21
In MUST-T10-4, a completeness finding that makes the audit fail is
distinct from a warning that only makes the guarantee conditional.
The verification algorithm states that distinction by behaviour
(Section 12).
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15.12. T11: Checkpoint suppression or rollback
Checkpoint suppression and rollback, and the witness that detects
them, are addressed in [CEDULON-CHECKPOINT]. The two requirements
below are defined here because the core label set and the
reconciliation depend on them.
+=============+====================================================+
| ID | Requirement |
+=============+====================================================+
| MUST-T11-1 | An epoch checkpoint MUST be COSE-signed and MUST |
| | bind epoch number, time window, receipt count, |
| | chain-head hash, per-currency totals, and the |
| | previous checkpoint hash. |
+-------------+----------------------------------------------------+
| MUST-T11-12 | Withheld checkpoint totals MUST be encoded as null |
| | in the signed payload. A verifier MUST report |
| | that the totals comparison was skipped and MUST |
| | treat the guarantee as conditional; receiptCount |
| | and chainHeadHash MUST still be checked. |
+-------------+----------------------------------------------------+
Table 22
15.13. T12: Settlement without a recorded receipt
The threats above are about a counterparty, a rail or an attacker.
This one is about the issuer's own implementation, and it produces
exactly the condition the rest of this document exists to make
detectable. Ordering, recovery and observability: [CEDULON-THREATS].
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+============+==================================================+
| ID | Requirement |
+============+==================================================+
| MUST-T12-1 | An issuer MUST NOT complete a settlement whose |
| | receipt it cannot record durably. The ability |
| | to record MUST be established before value |
| | moves, not after. |
+------------+--------------------------------------------------+
| MUST-T12-2 | Where a settlement has been made and its record |
| | cannot be completed, the issuer MUST undo the |
| | settlement in every place it still controls: in |
| | memory, on the rail ledger it controls, and in |
| | any later write it has not yet issued. A |
| | refused payment MUST NOT consume the nonce or |
| | the payment allowance it never used. |
+------------+--------------------------------------------------+
| MUST-T12-3 | Two issuers MUST NOT share one durable state. |
| | An implementation that permits it MUST fail |
| | loudly rather than let one writer overwrite the |
| | other's receipt, and the failure MUST name what |
| | an operator can act on. |
+------------+--------------------------------------------------+
| MUST-T12-4 | Where a settlement has entered a rail the issuer |
| | does not control, and the local record cannot be |
| | completed, the outcome is indeterminate. The |
| | issuer MUST NOT treat the payment as reversed, |
| | and MUST NOT return the authority to spend, |
| | unless it holds authenticated evidence that the |
| | rail did not complete the settlement or that a |
| | reversing entry completed. |
+------------+--------------------------------------------------+
Table 23
16. IANA Considerations
This document requests the registration of four media types in the
"Media Types" registry [RFC6838], in the standards tree, each
carrying the +cbor structured syntax suffix that [RFC8949] registers.
Each names one of the COSE_Sign1 objects this document defines and is
carried as the COSE content type header parameter (label 3) of that
object (Section 7). The value is a normative check inside a
protected header (MUST-T4-8, MUST-T6-5), which is why the names
cannot stay unregistered while that check stands. Registration in
the standards tree requires IETF approval; until then, an
implementation outside a closed deployment should treat these names
as placeholders that a registration may change. The provisional
registration procedure of [RFC6838] Section 5.2.1 is available to an
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Internet-Draft, and a provisional entry, if one is made, is
superseded by the registration this section requests.
The claim labels this document assigns inside the CBOR claim sets,
-70001 through -70402 (Section 7.1, Section 6.1), lie in the Private
Use range of the "CBOR Web Token (CWT) Claims" registry [RFC8392],
integer values less than -65536, and this document requests no
assignment for them. A later Standards Track revision that moves
them into the assigned range will request new labels then, without
reinterpreting these.
No other IANA action is requested.
The four templates follow. The checkpoint and inclusion types are in
[CEDULON-CHECKPOINT]. Fields that are the same for every one are
stated once, in the first, and the others say so.
16.1. application/cedulon-receipt+cbor
Type name: application
Subtype name: cedulon-receipt+cbor
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: binary. A COSE_Sign1 structure [RFC9052]
in deterministic CBOR [RFC8949], untagged, as profiled in
Section 6 and Section 7.
Security considerations: See Section 15 of this document. The
object is signed; its evidentiary weight depends on the verifier
holding the issuer key out of band (Section 11.1), never on a key
the object carries.
Interoperability considerations: The claim set is a CBOR map with
the labels and types stated in Section 7.1, encoded per [RFC8949]
Section 4.2.1. A decoder refuses a duplicate key (MUST-T4-18), an
input beyond its stated bounds (MUST-T4-19), and a non-empty
unprotected header (MUST-T4-21) by name rather than accepting it.
Published specification: This document, Section 6.
Applications that use this media type: Agent payment adapters,
policy decision points, auditors, and dispute-evidence tooling
that produce or verify Cedulon Spend Receipts.
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Fragment identifier considerations: N/A
Additional information: Deprecated alias names for this type: N/A.
Magic number(s): N/A. File extension(s): N/A. Macintosh file
type code(s): N/A.
Person and email address to contact for further information: Emek
Can Dogru, e.dogru@cedulon.com
Intended usage: COMMON
Restrictions on usage: N/A
Author: Emek Can Dogru
Change controller: IETF
16.2. application/cedulon-manifest+cbor
Type name: application
Subtype name: cedulon-manifest+cbor
Encoding considerations: binary. A COSE_Sign1 structure in
deterministic CBOR, untagged, as profiled in Section 5 and
Section 7.
Security considerations: See Section 15 of this document. A
manifest is an offer signed before payment; it binds terms, not
delivery, and is verified only against a publisher key held out of
band (Section 11.4).
Interoperability considerations: As for application/cedulon-
receipt+cbor; the labels are those of the manifest table in
Section 7.1, and the payee label is encoded only when present.
Published specification: This document, Section 5.
Applications that use this media type: Payees and marketplaces that
publish signed offers to paying agents, and verifiers reconciling
receipts against those offers.
Required parameters, optional parameters, fragment identifier
considerations, additional information, contact, intended usage,
restrictions on usage, author, change controller: As for
application/cedulon-receipt+cbor.
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16.3. application/cedulon-decision+cbor
Type name: application
Subtype name: cedulon-decision+cbor
Encoding considerations: binary. A COSE_Sign1 structure in
deterministic CBOR, untagged, as profiled in Section 9 and
Section 7.
Security considerations: See Section 15 of this document. A
Decision Token is consumed at the gate by the party that issued it
(Section 11.3); it is not an input to the retrospective audit
(Section 12.1), and a verifier that treated it as one would be
claiming a check the audit does not make.
Interoperability considerations: As for application/cedulon-
receipt+cbor; the labels are those of the Decision Token table in
Section 7.1, all five always present.
Published specification: This document, Section 9.
Applications that use this media type: Policy decision points and
the payment adapters that consume their allow decisions.
Required parameters, optional parameters, fragment identifier
considerations, additional information, contact, intended usage,
restrictions on usage, author, change controller: As for
application/cedulon-receipt+cbor.
16.4. application/cedulon-countersign+cbor
Type name: application
Subtype name: cedulon-countersign+cbor
Encoding considerations: binary. A detached COSE_Sign1 structure in
deterministic CBOR, untagged, as profiled in Section 6.1, whose
payload carries the exact issuer receipt octets it countersigns.
Security considerations: See Section 15 of this document. A
countersignature that does not verify under a payee key held out
of band carries no evidentiary weight and cannot move the verdict
on the receipt it travels beside (Section 6.1, Section 11.2).
Interoperability considerations: As for application/cedulon-
receipt+cbor; the optional deliveredHash claim is a 32-octet byte
string and is read as absent when it is not.
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Published specification: This document, Section 6.1.
Applications that use this media type: Payees that acknowledge a
receipt and, optionally, bind the bytes they delivered.
Required parameters, optional parameters, fragment identifier
considerations, additional information, contact, intended usage,
restrictions on usage, author, change controller: As for
application/cedulon-receipt+cbor.
17. Implementation Status
This section is to be removed before publishing as an RFC.
RFC 7942 [RFC7942] note. Detailed status is kept in the companion
repository, where it can be corrected without a revision of this
document.
Implementation: A companion implementation with a runnable
verification suite at https://github.com/dogrucanemek-alt/cedulon
(https://github.com/dogrucanemek-alt/cedulon). The code is a
profile of this document, not a second specification. This -00 is
not an IETF working-group item.
Maturity: Research code by a single implementer. Three readers have
run the code on their own machines against a pinned commit and
reported figures matching the author's: two from a clean clone of
the whole suite, one re-running the published reproduction. That
is byte-stability across environments and not an independent
implementation; the same code agreeing with itself on three
machines rules out a local accident and nothing more. One reader
reports an independent implementation of the Signed Statement
identity, kept deliberately separate from this codebase; no
independent implementation of the reconciliation algorithm is
known to the author. One reader rebuilt the regenerated receipt
vector of Appendix A from this text alone, in an independent
toolchain, and obtained the published 307 octets byte for byte,
SHA-256
0f1fe8859faf25de906b08142674f1270656d8ea7bfc00853c2fc6e9d3f5a10b;
that reader had read parts of the public repository and says so,
so it is not a clean-room result.
Coverage: The receipt, checkpoint, extract, reconciliation and
verification algorithm are implemented, including the transparency
witness input, the withheld and not-anchored conditions, and
signed totals redaction. Every requirement added in the posted
series [CEDULON-DT] is covered by a red-then-green case written
before the text, with one exception: the reversal branch of MUST-
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T12-4 is specified and not executed, because this tree carries no
authenticated external-rail path. MUST-T6-7, the one requirement
this document adds beyond that series, is likewise specified and
not executed: no case in the suite compares a settlement's
timestampMs to a Decision Token's expiryMs. The escrow role,
reversal, refund and partial settlement are not implemented. The
witness used in the suite is the in-process log that MAY-T11-6
permits, a Merkle tree that issues inclusion proofs; tier 2 of
[CEDULON-CHECKPOINT] (The transparency witness) is exercised
against it red-then-green, and the implementation has not been run
against a deployed Transparency Service.
Continuous integration runs the pre-release suite - the post-
release registry checks are a separate job, deliberately excluded,
so "the suite" names exactly what was measured - on three hosted
runners, each as a non-root user: Linux, macOS and Windows. At
the commit this revision describes, all three assert every case,
577 of 577, with none skipped. A local Windows run without
symbolic-link privilege skips four POSIX-mode cases with a stated
reason rather than passing silently.
Licensing: Apache-2.0.
Contact: The author of this document.
Experience: The posted series [CEDULON-DT] was driven by what
readers found rather than by a plan. T12 came from none of them:
it was found while writing an adversarial task, in the ordering
the implementation itself used.
The manifest root (MUST-T4-15) and the gate's refusal to settle
against a manifest it cannot attribute (MUST-T4-16) were published as
0.4.0 rather than as a patch: the gate had been answering 200 to an
unattributable manifest and writing that manifest's hash into the
receipt, and refusing it is a change in behaviour that a version
number ought to announce.
Note on distribution: everything the posted series [CEDULON-DT] added
is in the published packages at version 0.9.0, and the workspace
publishes 0.13.1 as this revision is written. A reader can check a
claim against an installed package rather than against a working
tree.
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18. Evolution and Future Work (Informative)
This document is an individual Internet-Draft. If the work is taken
up, the intended track is a Standards Track profile of COSE [RFC9052]
and CWT [RFC8392] for agent-spend receipts. Two extensions are
sketched and not specified here: re-attestation of receipts when a
signature algorithm is retired [REATTEST], and reconciliation
evaluated as settlements arrive rather than per epoch [STREAMING].
The same completeness check could apply to other consumed resources,
such as compute or data; this document does not specify those
profiles.
19. Informative Notes on Adjacent Protocols
x402 [X402] uses HTTP 402 [RFC9110] to negotiate stablecoin payment.
AP2 [AP2] uses signed mandates as verifiable credentials. Cedulon
does not replace either protocol. Profiles built on HTTP Message
Signatures [RFC9421] authenticate bots; they are not a spend receipt.
The drafts below are complementary, and none of them defines rail-
extract completeness. draft-bates-atp [BATES-ATP] covers tamper-
evident causal lineage as a signed directed acyclic graph. draft-
vauban-x402-stark-receipts [VAUBAN] specifies x402 receipt-format
variants that a Cedulon Spend Receipt MAY carry as a rail proof.
draft-schrock-ep-outcome-binding [SCHROCK] compares authorized action
bytes to independently observed effects. draft-marques-asqav-
compliance-receipts [MARQUES] profiles access-control action receipts
(the broader Acta family includes [ACTA]). draft-hopley-x402-
compliance-receipt [HOPLEY] records an admission-time compliance
decision. draft-abak-agent-control-delivery-evidence [ABAK] states
evidence requirements for a governance control - stop, suspend,
revoke - travelling toward the component expected to constrain a
runtime, and keeps emission, receiver-side observation, enforcement
outcome and observed control effect as separate results. Its object
moves the other way from this one: Cedulon reconciles a spend that
already happened against what the rail reported, and evidences
neither the delivery of a control instruction nor its enforcement. A
denied spend leaves no portable artifact here at all - a Decision
Token encodes an allow (Section 9) - so what a Cedulon audit says
about a refusal it says through the settlement that did not appear on
the extract, which is an effect observation over a declared
population and not an acknowledgement from an enforcement point. Its
bounded-population rule and this document's MUST-T10-18 and MUST-
T10-19 are the same kind of bound on two different objects.
draft-kuehlewind-audit-architecture [KUEHLEWIND-AUDIT], the
architecture a Cedulon audit is intended to be read within, is
described in Section 1; it also covers propagation of audit context
across domains and optional attestation under the Remote ATtestation
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procedureS (RATS) architecture. draft-birkholz-verifiable-agent-
conversations [BIRKHOLZ-VAC] defines a COSE-signed record of an
agent's conversation - session metadata, messages, tool invocations,
reasoning traces - for the same Transparency Services. A Spend
Receipt is the kind of artifact such a record would name for a
payment step; neither document profiles the other, and the
conversation record does not define rail-extract completeness.
20. References
20.1. Normative References
[CEDULON-CHECKPOINT]
Dogru, E. C., "Cedulon Checkpoints: Epoch Witnesses and
Transparency", 2026, <https://github.com/dogrucanemek-
alt/cedulon/blob/master/spec/draft-dogru-cedulon-
checkpoint-00.md>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/rfc/rfc6234>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/rfc/rfc6838>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/rfc/rfc7493>.
[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
Signature Algorithm (EdDSA)", RFC 8032,
DOI 10.17487/RFC8032, January 2017,
<https://www.rfc-editor.org/rfc/rfc8032>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
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[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/rfc/rfc8392>.
[RFC8410] Josefsson, S. and J. Schaad, "Algorithm Identifiers for
Ed25519, Ed448, X25519, and X448 for Use in the Internet
X.509 Public Key Infrastructure", RFC 8410,
DOI 10.17487/RFC8410, August 2018,
<https://www.rfc-editor.org/rfc/rfc8410>.
[RFC8785] Rundgren, A., Jordan, B., and S. Erdtman, "JSON
Canonicalization Scheme (JCS)", RFC 8785,
DOI 10.17487/RFC8785, June 2020,
<https://www.rfc-editor.org/rfc/rfc8785>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/rfc/rfc9052>.
[RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053,
August 2022, <https://www.rfc-editor.org/rfc/rfc9053>.
[RFC9864] Jones, M.B. and O. Steele, "Fully-Specified Algorithms for
JSON Object Signing and Encryption (JOSE) and CBOR Object
Signing and Encryption (COSE)", RFC 9864,
DOI 10.17487/RFC9864, October 2025,
<https://www.rfc-editor.org/rfc/rfc9864>.
[RFC9942] Steele, O., Birkholz, H., Delignat-Lavaud, A., and C.
Fournet, "CBOR Object Signing and Encryption (COSE)
Receipts", RFC 9942, DOI 10.17487/RFC9942, June 2026,
<https://www.rfc-editor.org/rfc/rfc9942>.
[RFC9943] Birkholz, H., Delignat-Lavaud, A., Fournet, C., Deshpande,
Y., and S. Lasker, "An Architecture for Trustworthy and
Transparent Digital Supply Chains", RFC 9943,
DOI 10.17487/RFC9943, June 2026,
<https://www.rfc-editor.org/rfc/rfc9943>.
20.2. Informative References
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[ABAK] Abak, A. T., "Evidence Requirements for Agent Control
Delivery and Outcome Reconciliation", August 2026,
<https://datatracker.ietf.org/doc/draft-abak-agent-
control-delivery-evidence/>.
[ACTA] Farley, T., "Signed Decision Receipts for Machine-to-
Machine Access Control", June 2026,
<https://datatracker.ietf.org/doc/draft-farley-acta-
signed-receipts/>.
[AP2] Google Agentic Commerce, "Agent Payments Protocol (AP2)",
September 2025,
<https://ap2-protocol.org/ap2/specification/>.
[BATES-ATP]
Bates, D., "Agent Transaction Protocol (ATP)", May 2026,
<https://datatracker.ietf.org/doc/html/draft-bates-atp>.
[BIRKHOLZ-VAC]
Birkholz, H., Heldt, T., and O. Steele, "Verifiable Agent
Conversation Records", August 2026,
<https://datatracker.ietf.org/doc/draft-birkholz-
verifiable-agent-conversations/>.
[CEDULON-DT]
Dogru, E. C., "Cedulon: An Audit Layer for Agent-to-Agent
Commerce", 2026,
<https://datatracker.ietf.org/doc/draft-dogru-cedulon/>.
[CEDULON-THREATS]
Dogru, E. C., "Cedulon Threat Narratives", 2026,
<https://github.com/dogrucanemek-
alt/cedulon/blob/master/spec/draft-dogru-cedulon-threats-
00.md>.
[CPB] Mih, S. and A. Sokolov, "Canonical Payload Binding: A
Signed Statement Construction Profile", August 2026,
<https://datatracker.ietf.org/doc/draft-mih-sokolov-scitt-
payload-binding/>.
[GRIGG] Grigg, I., "Triple Entry Accounting", 2005,
<https://iang.org/papers/triple_entry.html>.
[HOPLEY] Hopley, C., "Categorical Compliance Screening Receipt
Format for Agentic-Payment Flows", May 2026,
<https://datatracker.ietf.org/doc/draft-hopley-x402-
compliance-receipt/>.
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[KUEHLEWIND-AUDIT]
Kuehlewind, M. and H. Birkholz, "An Architecture for
Auditing AI Agent Delegation and Interactions", May 2026,
<https://datatracker.ietf.org/doc/draft-kuehlewind-audit-
architecture/>.
[MARQUES] Gomes Marques, J. A., "Compliance Profile of Signed Action
Receipts for AI Agents", July 2026,
<https://datatracker.ietf.org/doc/draft-marques-asqav-
compliance-receipts/>.
[PACIOLI] Pacioli, L., "Summa de arithmetica, geometria, proportioni
et proportionalita", 1494.
[REATTEST] Dogru, E. C., "Cedulon Re-Attestation: Carrying Spend
Evidence Across Algorithm Retirement", August 2026,
<https://github.com/dogrucanemek-
alt/cedulon/blob/e681e24d1b29912d8c190259c2ea9f4f9538c29d/
spec/draft-dogru-cedulon-reattestation-00.md>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/rfc/rfc7942>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
[RFC9421] Backman, A., Ed., Richer, J., Ed., and M. Sporny, "HTTP
Message Signatures", RFC 9421, DOI 10.17487/RFC9421,
February 2024, <https://www.rfc-editor.org/rfc/rfc9421>.
[SCHROCK] Schrock, I., "Outcome Binding for Authorized Actions and
Independently Observed Effects", July 2026,
<https://datatracker.ietf.org/doc/draft-schrock-ep-
outcome-binding/>.
[STREAMING]
Dogru, E. C., "Cedulon Streaming Reconciliation:
Continuous Completeness for Agent Spend", August 2026,
<https://github.com/dogrucanemek-
alt/cedulon/blob/e681e24d1b29912d8c190259c2ea9f4f9538c29d/
spec/draft-dogru-cedulon-streaming-00.md>.
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[VAUBAN] Vauban Research, "x402 STARK Receipt Format Extension",
May 2026, <https://datatracker.ietf.org/doc/draft-vauban-
x402-stark-receipts/>.
[X402] x402 Foundation, "x402: An Open Standard for Internet-
Native Payments", 2026, <https://www.x402.org/>.
Acknowledgments
Vernon Wharff showed that the object carrying the checkpoint
guarantee was neither profiled for registration nor read during
verification, and asked whether a recorded checkpoint absent from the
chain deserves its own identifier. Iman Schrock confirmed that
finding independently and drew its boundary.
Iman Schrock and Pablo Etcheverry ran the implementation against a
pinned commit and reported defects that shaped this document. Iman
Schrock found the extract-binding defects and proposed their repair,
asked whether the profile should accept a pinned witness key, and
corrected this document's description of what its continuous
integration measures. He is also the author of [SCHROCK], cited here
as adjacent work, and the reader whose independent implementation of
the Signed Statement identity is noted in Section 17; he asked for it
to be kept separate from any cross-implementation claim about
Cedulon, and that separation is his and is recorded here as he stated
it. Pablo Etcheverry found that a repeated reference hid the
unaccounted amount, ran the suite on a platform its author had not,
and found that nothing compared a settlement's clock to the clock of
the decision that authorized it.
Nicholas Templeman ran the suite from a clean clone, corrected two
claims written about that run, and classified his own run as a
repetition of the author's checks rather than an independent
implementation. Walter Hawkins did not run it; he pressed for the
run to be stated precisely enough to be repeatable.
Tiago Pinto ran the Appendix A vectors in an independent toolchain
before reading the text, confirmed the signatures, the SPKI-derived
kid, and deterministic re-encoding byte for byte, and listed the
places where an independent implementation could not be built from
the text. The witness tiers, the key-resolution rule, the extract
shape, issuer order, the boundary allowance, and the countersignature
and delivery bindings follow that list, and Section 7.3 answers a
later point of his. He consented to that run being recorded as the
first run of these vectors outside the companion codebase and not as
an independent implementation.
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Steven Mih and Anton Sokolov published the canonicalization vectors
of [CPB]; running them through this profile's [RFC8785] encoder put
the I-JSON precondition on the page as a rule.
None of them reviewed this text, and any error in it is the author's.
Field survey notes and the informative threat-model narrative in the
companion repository helped shape the requirement identifiers used
here. Those identifiers are defined in Section 15 and, for T11, in
[CEDULON-CHECKPOINT].
Appendix A. Test Vectors
These vectors use RFC 8032 Ed25519 secret scalar #1 (fixture only;
never a production key). Hex is lowercase.
The vectors below MUST stand as the locked tests of this document: an
implementation matches them or it does not, and where an
implementation and a vector disagree, one of the two is wrong and
this document does not say in advance which.
Receipt COSE_Sign1:
Claims: payer=payer-1, payee=payee-1, amount=1, currency=USD,
policyHash=
fca4142da8ad241d24928227893894f4b5365efb746a4529fe9df0119d10da2c (the
SHA-256 of the UTF-8 octets of the ASCII string cedulon/appendix-
policy, standing in for a canonical policy document; the field's
input rule is in Section 8.1), manifestHash=null, noManifest=true,
x402PaymentRef=null, timestampMs=1700000000000,
nonce=n100000000000000, prevReceiptHash=null, outcome=aborted.
COSE_Sign1 hex (whitespace ignored):
845830a301320378206170706c69636174696f6e2f636564756c6f6e2d
726563656970742b63626f72044806e3fd8fda29bb60a058bbac3a0001
11706770617965722d313a000111716770617965652d313a0001117261
313a00011173635553443a000111747840666361343134326461386164
323431643234393238323237383933383934663462353336356566623734
366134353239666539646630313139643130646132633a00011175f63a
00011176f53a00011177f63a000111781b0000018bcfe568003a000111
79706e3130303030303030303030303030303a0001117af63a0001117b
6761626f7274656458400a24269b7521d409ebe462db297c3aa25b23d6
c697aa4a864b1b3a3edb5b30537b34b048a797073eaee41af371effb68
ecbb47b80e62d7e775e8cae5b066c30c
Manifest COSE_Sign1:
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Body: description=fixture-goods, amount=1, currency=USD,
acceptanceCriteriaHash=
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (the
SHA-256 of an empty delivery; the field is a digest of the exact
delivery bytes, so the vector carries a well-formed one),
cancelCondition=none, expiresAtMs=1700000000000, ap2MandateHash=null.
COSE_Sign1 hex (whitespace ignored):
845831a301320378216170706c69636174696f6e2f636564756c6f6e2d
6d616e69666573742b63626f72044806e3fd8fda29bb60a05889a73a00
0112386d666978747572652d676f6f64733a0001123961313a0001123a
635553443a0001123b7840653362306334343239386663316331343961
666266346338393936666239323432376165343165343634396239333
463613439353939316237383532623835353a0001123c646e6f6e653a
0001123d1b0000018bcfe568003a0001123ef65840599b5b1cc7bfd3fe
8b8e65cdd876652aeca13660e6bdccc93afe12188a295b20fdfe8e6e48
ae447dc74ccb0f13383f0f43f0f67f288d61a6395e95e2038e320d
Appendix B. Finding Codes
+====================+=============+===============================+
| Code | Effect | Meaning |
+====================+=============+===============================+
| settlement- | audit fails | Extract row has no matching |
| without-receipt | | settled receipt, or a |
| | | repeating ref settled more |
| | | than it receipted |
+--------------------+-------------+-------------------------------+
| receipt-without- | audit fails | Settled receipt ref is not on |
| settlement | | the extract |
+--------------------+-------------+-------------------------------+
| settlement- | audit fails | Same ref, different amount or |
| mismatch | | currency, including a |
| | | repeating ref that settled |
| | | less than it receipted |
+--------------------+-------------+-------------------------------+
| duplicate-ref | audit fails | Ref appears more than once on |
| | | one side |
+--------------------+-------------+-------------------------------+
| settled-without- | audit fails | outcome is settled and |
| ref | | x402PaymentRef is null |
+--------------------+-------------+-------------------------------+
| receipt-chain- | audit fails | Signature or prevReceiptHash |
| break | | failed, or the links cannot |
| | | place a receipt (issuer |
| | | order, step 6) |
+--------------------+-------------+-------------------------------+
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| unauthenticated- | guarantee | No verifier-supplied rail |
| extract | conditional | key, whatever the extract |
| | | carries: a signature that |
| | | verifies establishes internal |
| | | consistency and not that the |
| | | named rail produced the |
| | | extract, and one that fails |
| | | or is refused is not a key |
| | | verdict either. The same |
| | | code is reported when a rail |
| | | key is pinned and no extract |
| | | was presented at all, because |
| | | there is nothing to check the |
| | | pin against. A presented |
| | | extract that does not verify |
| | | under a pinned key is |
| | | extract-key-mismatch instead |
+--------------------+-------------+-------------------------------+
| extract-key- | audit fails | Extract is signed by a key |
| mismatch | | other than the pinned rail |
| | | key, or does not verify |
| | | against it |
+--------------------+-------------+-------------------------------+
| settlement- | guarantee | The pinned rail key refused |
| comparison-skipped | conditional | the presented extract, so its |
| | | rows were not reconciled |
| | | against the receipts (MUST- |
| | | T10-20). The code says what |
| | | did not run; the refusal |
| | | itself is reported as |
| | | extract-key-mismatch |
+--------------------+-------------+-------------------------------+
| trust-key- | audit fails | A pinned key - rail, issuer, |
| unreadable | | or manifest publisher - could |
| | | not be decoded; the |
| | | verifier's configuration is |
| | | at fault, and nothing falls |
| | | back to the keys the objects |
| | | carry |
+--------------------+-------------+-------------------------------+
| issuer-key- | audit fails | An object is signed by a key |
| mismatch | | other than the pinned issuer |
| | | key, or does not verify under |
| | | it at all, so it is not |
| | | coverage for anything it |
| | | names. A checkpoint reaches |
| | | this code by either route: |
| | | unlike a receipt, which is |
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| | | named in the chain walk as |
| | | receipt-chain-break when it |
| | | claims the pin and fails, a |
| | | checkpoint that claims the |
| | | pin and fails is reported |
| | | here and leaves its window |
| | | uncovered |
+--------------------+-------------+-------------------------------+
| countersign-key- | conditional | A countersignature verifies |
| mismatch | | under a key other than the |
| | | one pinned for that payee; |
| | | unattributable, discarded as |
| | | approval evidence, and the |
| | | receipt it rode beside is |
| | | unaffected (Section 6.1) |
+--------------------+-------------+-------------------------------+
| countersign- | conditional | A payee key is pinned and a |
| missing | | settled receipt for that |
| | | payee carries no attributable |
| | | countersignature; a discarded |
| | | garbage or foreign-key object |
| | | leaves this open |
+--------------------+-------------+-------------------------------+
| unauthenticated- | conditional | No verifier-supplied issuer |
| issuer | | key and at least one receipt |
| | | or checkpoint presented; |
| | | their signatures are checked |
| | | against the keys the objects |
| | | carry (Section 7.3), which |
| | | establishes that each object |
| | | is internally consistent and |
| | | not that the named issuer |
| | | produced it |
+--------------------+-------------+-------------------------------+
| unauthenticated- | conditional | No verifier-supplied payee |
| countersigner | | key; a countersignature is |
| | | present but proves no |
| | | approval |
+--------------------+-------------+-------------------------------+
| unauthenticated- | conditional | No verifier-supplied manifest |
| manifest | | key and a Trade Manifest was |
| | | presented; its signature is |
| | | not checked at all, because |
| | | the check that exists under a |
| | | pin (manifest-key-mismatch) |
| | | has no key to run against and |
| | | the key the manifest carries |
| | | is not a fallback for one. |
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| | | An audit presented with no |
| | | Trade Manifest is not this |
| | | condition |
+--------------------+-------------+-------------------------------+
| manifest-key- | audit fails | A presented Trade Manifest is |
| mismatch | | signed by a key other than |
| | | the pinned publisher key, or |
| | | does not verify against it |
+--------------------+-------------+-------------------------------+
| manifest-covers- | conditional | A presented Trade Manifest is |
| no-receipt | | referenced by no presented |
| | | receipt, including aborted |
| | | ones and those outside the |
| | | extract window; the manifest |
| | | states terms no presented |
| | | receipt names. It is |
| | | reported on what was |
| | | presented, not on whether the |
| | | manifest was attributed, so |
| | | it appears beside manifest- |
| | | key-mismatch as well |
+--------------------+-------------+-------------------------------+
| manifest-terms- | audit fails | A receipt names this Trade |
| mismatch | under a | Manifest but departs from it |
| | usable | in amount, currency, |
| | issuer pin; | settlement time, or, where |
| | warning | the manifest states one, |
| | without one | payee. A manifest refused by |
| | | a stated publisher pin is not |
| | | compared at all; a gate |
| | | applying MUST-T8-2 and MUST- |
| | | T3-3 would have refused the |
| | | payment. The two severities |
| | | are the two branches of MUST- |
| | | T8-9 |
+--------------------+-------------+-------------------------------+
| extract-scope- | audit fails | A record falls outside the |
| mismatch | | declared window, or the |
| | | extract does not cover the |
| | | expected account, rail, or |
| | | window |
+--------------------+-------------+-------------------------------+
| extract- | audit fails | A caller-supplied settlement |
| settlement- | | list disagrees with the |
| mismatch | | extract on ref, amount, |
| | | currency or timestamp, which |
| | | are the fields compared; the |
| | | extract is authoritative. A |
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| | | beneficiary that differs is |
| | | not part of this comparison |
| | | and is reached by |
| | | beneficiary-mismatch, against |
| | | the receipt payee |
+--------------------+-------------+-------------------------------+
| malformed-amount | audit fails | An amount on a ref already |
| | | reported as repeating that |
| | | could not be parsed as an |
| | | integer |
+--------------------+-------------+-------------------------------+
| unstated-audit- | guarantee | A supplied rail pin states no |
| window | conditional | period, so the extract |
| | | defined its own. Where no |
| | | rail key is pinned at all the |
| | | period is equally unstated, |
| | | and unauthenticated-extract |
| | | is the condition reported |
+--------------------+-------------+-------------------------------+
| unstated-audit- | guarantee | A supplied rail pin states no |
| scope | conditional | account or no rail, so the |
| | | extract defined the |
| | | settlement path it reported |
| | | on. The same "no pin at all" |
| | | case is unauthenticated- |
| | | extract |
+--------------------+-------------+-------------------------------+
| countersign-bad | conditional | Present payee |
| | | countersignature failed |
| | | verify (signature, content |
| | | type, or payload binding); |
| | | unattributable, discarded as |
| | | approval evidence. One |
| | | verifiable under another key |
| | | is countersign-key-mismatch |
+--------------------+-------------+-------------------------------+
| carried-key- | conditional | An object verifies under a |
| mismatch | | pinned issuer key but the key |
| | | carried beside its signature |
| | | is a different one; the |
| | | unsigned surface was |
| | | rewritten, the object stays |
| | | attested (Section 11.1) |
+--------------------+-------------+-------------------------------+
| boundary-deferred | conditional | An unmatched item sits within |
| | | the declared clockSkewMs of |
| | | the window edge; deferred to |
| | | the adjacent window rather |
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| | | than reported as a |
| | | completeness failure (step 5) |
+--------------------+-------------+-------------------------------+
| beneficiary- | audit fails | A settlement record declares |
| mismatch | | a beneficiary and the matched |
| | | receipt's payee differs |
+--------------------+-------------+-------------------------------+
| counterparty- | scope | Neither the manifest names a |
| unbound | record; | payee nor any settlement |
| | verdict and | record declares a |
| | guarantee | beneficiary: ref, amount and |
| | unchanged | currency closed against the |
| | | payer's account extract, and |
| | | the counterparty's identity |
| | | was not bound |
+--------------------+-------------+-------------------------------+
| delivery-mismatch | audit fails | An attributable |
| | | countersignature carries |
| | | deliveredHash and it differs |
| | | from the acceptance-criteria |
| | | hash of a Trade Manifest the |
| | | audit did not refuse; both |
| | | ends are signed (MAY-T8-11). |
| | | Where a stated publisher pin |
| | | refuses the manifest, its |
| | | acceptance hash founds |
| | | nothing and this comparison |
| | | is not made (MUST-T8-9) |
+--------------------+-------------+-------------------------------+
| malformed-policy- | audit fails | A hash-shaped claim does not |
| hash (and its | | match the 64-lowercase-hex |
| family: malformed- | | grammar of Section 7.1; the |
| request-hash, | | claim is named in the code |
| malformed- | | |
| acceptance- | | |
| criteria-hash, | | |
| malformed- | | |
| manifest-hash, | | |
| malformed-receipt- | | |
| hash, malformed- | | |
| prev-receipt-hash, | | |
| malformed-chain- | | |
| head-hash, | | |
| malformed-prev- | | |
| checkpoint-hash, | | |
| malformed-ap-two- | | |
| mandate-hash) | | |
+--------------------+-------------+-------------------------------+
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Table 24
Appendix C. Worked Example: A 10.00 TRY Spend
This appendix is informative. An agent pays 10.00 Turkish lira (TRY)
for a file. Amounts are integer minor units, so the amount is 1000.
The run used the companion implementation with keys generated for the
run; the keys are not published, so signatures and hashes are not
shown. No real rail was involved.
1. The PDP allows the request (amount 1000, currency TRY, payee
shop-1) and the adapter settles it under rail reference x402-n-
10try-example-0001.
2. The Receipt Issuer signs a Spend Receipt with these claims
(policyHash omitted):
payer=agent-1 payee=shop-1 amount=1000 currency=TRY
manifestHash=null noManifest=true
x402PaymentRef=x402-n-10try-example-0001
timestampMs=1789400600000 nonce=n-10try-example-0001
prevReceiptHash=null outcome=settled
3. The rail signs an extract for account acct-1, rail rail-1 and the
one-hour window [1789400000000, 1789403600000), with one row: ref
x402-n-10try-example-0001, amount 1000, currency TRY. The issuer
signs one checkpoint for the same hour.
4. A verifier that holds the issuer key and the rail key, and states
that account, rail and window, reconciles them. The result is
balanced under an unconditional guarantee. It carries the scope
record counterparty-unbound, because no manifest names a payee.
The same audit was then run against an extract the rail signed with a
second 10.00 TRY row, ref rail-ref-unreceipted, twenty minutes into
the window, that no receipt names. The verifier reported settlement-
without-receipt for that ref and the audit failed. That row is the
case this document exists to detect: money that left through the rail
without a receipt.
The same control has also been run once with real money, by a related
implementation from the same author that records a spend as a signed
decision and effect record rather than as the Spend Receipt of this
document. On 6 September 2026 an agent asked to spend 10.00 TRY on
advertising, the policy deferred the request, it was approved under
the operator's account, and the amount was paid by card to the
advertising platform. The next day the payer's bank statement
arrived, and its line for that payment was reconciled against the
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approved spend: one matched, none unaccounted for. Two limits apply.
The statement was received as an image rather than as a signed file
from the bank, and the line was transcribed from it, so under this
document the result would be conditional (unauthenticated-extract).
The line also did not carry the spend reference, because the platform
billed under its own descriptor, so the match rested on amount,
currency and date alone.
Author's Address
Emek Can Dogru
VERAX TEKNOLOJI LIMITED SIRKETI
Email: e.dogru@cedulon.com
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