Data-Purpose Laundering Prevention: Execution-Finality for Preventing Cross-Domain Data Reuse
draft-das-purpose-execution-finality-00
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draft-das-purpose-execution-finality-00
Individual Submission S. Das
Internet-Draft Independent Inventor
Intended status: Informational 9 September 2026
Expires: 13 March 2027
Data-Purpose Laundering Prevention: Execution-Finality for Preventing
Cross-Domain Data Reuse
draft-das-purpose-execution-finality-00
Abstract
Systems that collect data for one stated purpose routinely permit
that data, or values derived from it, to be consumed by a second
system for a different purpose -- not because the second use was
authorized, but because nothing in the protocol path was capable of
refusing it. The most common technical control in deployment today
is a self-asserted purpose string: a "purpose" claim in a token, a
field in an API request, a comment in a data-sharing agreement. A
self-asserted string is evidence of intent, not proof of authority,
and it fails precisely when it matters most -- when the requester
lies.
This document specifies an execution-finality architecture in which a
Candidate Act to read, transmit, or derive from a protected data
object does not become effective merely because a caller labels its
request with an allowed purpose. Effect is withheld until a
Protected Enforcement Domain verifies caller identity, requested
operation, and destination against binding records -- not against
caller-supplied metadata -- and issues a scoped, non-bearer Execution
Handle before any release occurs. The document works through a
single running example (a delivery address later targeted by an
unrelated advertising system) to make the failure mode and the
enforcement boundary concrete, and states plainly which part of the
problem this architecture does not solve. It is offered as an
architectural pattern for discussion, not as a proposal for a new
wire protocol.
Cross-referencing data across systems, including in advertising, is a
legitimate and economically necessary function, and this document
does not argue for eliminating it; doing so would stall innovation
and materially harm the businesses that depend on it. What this
architecture offers such systems is a way to make an authorized
combination of data technically verifiable at the moment it happens,
rather than leaving that boundary to rest on a data-sharing agreement
nobody downstream actually checks -- making lawful cross-referencing
demonstrable, not making cross-referencing itself the target.
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A further motivation is stated directly here because it shapes
several design choices in this document: the same technical capacity
that lets an advertising system profitably combine location and
behavioral signals across sources is, absent a verifiable purpose
boundary, also capable of exposing patterns -- such as the movement
of military personnel or the operating rhythm of critical
infrastructure -- to a party in a jurisdiction other than the one the
data was collected in. Aggregated commercial location and behavioral
data has, in publicly reported incidents, already been shown capable
of revealing exactly this kind of sensitive pattern. This document
does not ask commercial systems to stop combining data for legitimate
purposes; it asks that a combination authorized for commercial
targeting be technically distinguishable, at the moment of use, from
a combination that has crossed into cross-jurisdictional
intelligence-gathering territory the data was never authorized for.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 13 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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Self-Asserted Purpose Is Not Verifiable Purpose . . . . . 6
3.2. Attestation Answers a Different Question Than
Authorization . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Derived Data Carries the Restriction, Not Just the
Value . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4. The Residual Limit: Plaintext Already Released . . . . . 7
4. Architecture Overview . . . . . . . . . . . . . . . . . . . . 7
5. Worked Example . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Collection: Binding the Data Object to a Permitted Use . 8
5.2. A Legitimate Request . . . . . . . . . . . . . . . . . . 8
5.3. An Unauthorized Request . . . . . . . . . . . . . . . . . 9
5.4. A Relabeled Request . . . . . . . . . . . . . . . . . . . 10
5.5. A Request From Inside an Attested Enclave . . . . . . . . 10
5.6. A Request for a Derived Value . . . . . . . . . . . . . . 10
5.7. What This Architecture Does Not Close . . . . . . . . . . 11
6. Threat Model . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Relation to Existing Work . . . . . . . . . . . . . . . . . . 12
8. Relevance to IETF Working Groups . . . . . . . . . . . . . . 12
8.1. GNAP . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.2. OAUTH . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.3. RATS . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.4. SPICE . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.5. SECDISPATCH . . . . . . . . . . . . . . . . . . . . . . . 14
8.6. PEARG (IRTF) . . . . . . . . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
12. Intellectual Property and Licensing . . . . . . . . . . . . . 15
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
14. Resources . . . . . . . . . . . . . . . . . . . . . . . . . . 15
15. Latency Characteristics (Non-Normative) . . . . . . . . . . . 16
16. Feasibility and Legacy System Integration . . . . . . . . . . 18
17. Normative References . . . . . . . . . . . . . . . . . . . . 21
18. Informative References . . . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 23
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1. Introduction
Purpose limitation is a stated requirement across data protection
law, sectoral regulation, and internal governance policy: data
collected for one purpose should not be repurposed for another
without new authority. It is, at the protocol level, almost never
enforced. What is typically enforced is that a request carries a
"purpose" value the requester chose to write down.
This gap is not a corner case. It is the default shape of most data-
sharing architectures in production today: an access-control check
confirms that a caller is _permitted to call the API_, and a
separate, unenforced convention -- a contract clause, a privacy
notice, a code comment -- says what the caller is supposed to do with
the response. Nothing in the request path distinguishes a truthful
purpose claim from a false one, because the claim was never checked
against anything the requester does not control.
This document uses a single concrete scenario to walk through what
changes when purpose is treated as something to be verified rather
than declared. A delivery application collects a home address in
order to fulfil an order. An unrelated advertising system later
attempts to use that same address to infer household income for ad
targeting. Every variation of that attempt -- a direct request, a
relabeled request, a request issued from inside an attested secure
enclave, a request for a value merely _derived_ from the address --
is traced through an enforcement boundary that answers one question
before doing anything else: is this caller, this operation, and this
destination actually authorized, based on records the caller cannot
write to?
The architecture generalizes past the delivery/advertising example to
any setting where data crosses an organizational, workload, or trust
boundary and the receiving side has an incentive to reuse it for
something other than what it was released for: cross-tenant AI agent
tool use, cross-border data transfer under jurisdictional
restriction, and inter-service data sharing inside a single company
under an internal purpose limitation policy are all instances of the
same problem. This document keeps the running example narrow so the
mechanism stays concrete; companion drafts in the same series
([DAS-EU-AI-ACT], [DAS-GLOBAL-PRIVACY], [DAS-PRECISION-EGRESS]) apply
the same underlying architecture to EU AI Act high-risk system
enforcement, general-purpose privacy-execution enforcement, and
precision-bounded data egress respectively.
[FUTURIUM-PURPOSE-LAUNDERING] develops the GDPR purpose-limitation
and high-risk AI governance framing of this same delivery/advertising
pattern in regulatory detail, and [FUTURIUM-PAPER-COMPLIANCE]
situates that framing within the broader argument for moving from
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paper compliance to technical enforcement under GDPR and the EU AI
Act; this document is the protocol-mechanics counterpart to that
discussion. See Section 14 for a Resources pointer to the drafts and
the runnable reference implementation that develop these mechanics
further.
The architecture does not claim to solve purpose limitation in
general. Section 5.7 and Section 6 state directly what remains
unsolved once data has been legitimately released as plaintext to an
authorized recipient.
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.
2. Terminology
Candidate Act: A request to read, transmit, transform, or derive
from a protected data object. A Candidate Act has no effect on
its own; it is a proposal for an effect.
Non-Effective State: The state of a Candidate Act prior to
validation. No data release, decryption, or downstream write
occurs while a Candidate Act remains in this state.
Protected Enforcement Domain (PED): The component that evaluates a
Candidate Act against binding records -- caller identity, order/
workflow state, recipient assignment, and policy version -- and
decides whether to advance it out of the Non-Effective State. The
PED does not accept caller-supplied metadata (such as a "purpose"
field) as evidence on its own.
Execution Handle: A short-lived, non-bearer, scoped authorization
issued by the PED after a Candidate Act passes validation. An
Execution Handle is bound to a specific data object, operation,
requester identity, and recipient; it is not a general-purpose
credential and is not intended to be transferable.
Finality Sink: The boundary at which a protected data object, or a
value derived from it, is actually released, decrypted, or written
to a destination store. The Finality Sink accepts only a valid,
unexpired, unrevoked Execution Handle.
Ledger-Anchored Validation Receipt (LAVR): An enforcement artifact
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-- not an audit log -- generated by the PED at the point a
Candidate Act is validated or rejected. A LAVR records the check
performed, its result, and a hash-chained, domain-signed anchor,
and is generated regardless of outcome.
Algorithmic Logic Fingerprint (ALF): A binding of the specific
operation or computation a Candidate Act requests (e.g., "obtain
delivery destination" versus "infer household income") to the set
of operations the governing policy actually permits on that data
object.
Capability-Validated Inbound Descriptor (CVID): The structured
description of an inbound Candidate Act -- caller, requested
operation, target object, destination -- that the PED evaluates
against binding records before issuing an Execution Handle.
Purpose Laundering: The practice, intentional or not, of obtaining
data or a value derived from it under one declared purpose and
consuming it under a different, unauthorized purpose, where the
receiving system's own request format permits the original purpose
label to travel with the data without being re-verified at the
point of reuse.
3. Problem Statement
3.1. Self-Asserted Purpose Is Not Verifiable Purpose
Most deployed systems that reference "purpose" at all do so as a
string carried in a token claim (e.g., a JWT claim, see [RFC7519]),
an API parameter, or a log field. That string is written by the same
party requesting access. A verification step that only checks
whether the field is present, well-formed, or drawn from an
enumerated list does not verify that the caller's actual operation
matches the label -- it verifies that the caller knows which label to
write.
3.2. Attestation Answers a Different Question Than Authorization
Remote attestation (see [RFC9334]) establishes that a piece of code
is running in an expected state on expected hardware. It does not
establish that the workload attested is authorized to perform a
specific operation on a specific data object. A correctly attested
enclave running an unauthorized computation is still an unauthorized
computation; attestation and purpose authorization are orthogonal
checks, and treating a passed attestation as implicit authorization
silently collapses that distinction.
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3.3. Derived Data Carries the Restriction, Not Just the Value
A value computed from restricted data (e.g., an income estimate
computed from a home address) is not automatically free of the
restriction that governed the source, even where the derived value
contains none of the original data verbatim. Without deliberate
propagation of source lineage to the derived object, a downstream
consumer of the derived value bypasses every control placed on the
source.
3.4. The Residual Limit: Plaintext Already Released
Once a protected value is legitimately released as plaintext to an
authorized recipient, this architecture -- or any architecture
operating at the request/response boundary -- cannot guarantee that
the recipient will not copy, screenshot, or re-transmit that value
outside the enforced path. Section 5.7 and Section 6 return to this
point; it is stated here because any reader evaluating this document
for what it does NOT do should not have to search for the admission.
4. Architecture Overview
The architecture separates two things that are frequently conflated
in deployed systems: the authority to request an operation, and the
capability to actually perform it. A Candidate Act carries no
capability. It is evaluated by a Protected Enforcement Domain
against records the requester did not write (order state, recipient
assignment, policy version, workload identity). Only on a pass does
the PED issue a scoped Execution Handle, and only a Finality Sink
presented with a valid Execution Handle releases, decrypts, or writes
the underlying value. Every evaluation, pass or fail, produces a
LAVR.
Requester --Candidate Act--> [Protected Enforcement Domain]
|
binding-record checks (Section 5.2)
|
pass? --------> Execution Handle
| |
fail --> LAVR Finality Sink
| |
LAVR release
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This differs from a conventional access-control gate in one load-
bearing respect: the PED's checks are defined over records external
to the request (what the request _is about_), not over fields
internal to the request (what the request _says about itself_). A
caller cannot pass validation by changing what it writes in its own
request.
5. Worked Example
5.1. Collection: Binding the Data Object to a Permitted Use
A customer provides a delivery address for a specific order. The
address is stored as a protected data object. A separate, integrity-
protected policy record binds that object to a single permitted
workflow, operation, and recipient class, with an explicit
disallowed-operation entry and an expiry:
Data object: address-619
Allowed workflow: delivery-order-842
Allowed operation: obtain delivery destination
Allowed recipient: assigned courier service
Disallowed operation: advertising-profile enrichment
Expiry: configured delivery-access deadline
Policy version: 38
The party that will later compute an advertising profile is never
given the address's decryption key or database credentials. If it
were, every check described below would be enforcement theater --
bypassable at will by the party the checks are meant to constrain.
5.2. A Legitimate Request
The delivery service submits a Candidate Act:
Read address-619, for order-842, send to assigned-courier-6,
operation: obtain delivery destination
The PED checks this against binding records, not against the
request's own claims:
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+======================================+=======================+
| Check | Evidence checked |
+======================================+=======================+
| Is this really the delivery service? | Authenticated |
| | workload identity |
+--------------------------------------+-----------------------+
| Does this order exist? | Order-management |
| | record |
+--------------------------------------+-----------------------+
| Does this address belong to the | Protected order-to- |
| order? | address association |
+--------------------------------------+-----------------------+
| Is this courier assigned? | Current courier- |
| | assignment record |
+--------------------------------------+-----------------------+
| Is the requested operation | Versioned policy (ALF |
| permitted? | match) |
+--------------------------------------+-----------------------+
| Is access still valid? | Order status, expiry, |
| | revocation state |
+--------------------------------------+-----------------------+
Table 1: PED validation checks for the delivery Candidate Act
A pass issues a short-lived Execution Handle scoped to this exact
address, order, operation, and recipient; the Finality Sink releases
the minimum necessary delivery data on presentation of that handle.
Any check that cannot be completed -- a stale record, an ambiguous
assignment, an expired policy version -- MUST be treated as a failed
check. The PED fails closed by default; it does not proceed on
missing or ambiguous evidence.
5.3. An Unauthorized Request
An advertising workload submits:
Read address-619, operation: infer household income,
destination: advertising-profile-database
Every check in Section 5.2 fails: the caller is not the delivery
service, the operation is not the permitted operation, and the
destination is not the permitted recipient. No Execution Handle is
issued, no address is released, and no decryption authority is
granted. The rejection occurs before the income computation begins
-- blocking only the resulting advertisement, after the profiling
computation has already run on the address, would not have prevented
the unauthorized use; it would only have hidden its output.
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5.4. A Relabeled Request
The advertising workload resubmits with a relabeled purpose field:
Purpose: delivery, order: order-842
This does not change the outcome. The PED's checks are defined over
the caller's authenticated identity, its destination, and its actual
delivery-workflow authority -- none of which change because the
request's purpose field changed. A caller that presents even a
validly issued delivery Execution Handle from the wrong workload
identity or toward the wrong destination MUST fail validation,
provided identity and destination binding are actually enforced at
the Finality Sink and not only at issuance time. Purpose, in this
architecture, is a conclusion the PED reaches from verifiable
relationships -- not an input the caller supplies.
5.5. A Request From Inside an Attested Enclave
Suppose the income-inference computation runs inside a hardware
Trusted Execution Environment (TEE) that successfully attests its own
integrity. A successful attestation establishes that the enclave is
running the code it claims to run; it does not establish that the
code is authorized to decrypt address-619 for this purpose. The PED
still evaluates workload identity and requested operation against the
same binding records, and an enclave running an income-profiling
workload receives no authority to decrypt a delivery address it was
never granted.
A caveat: if a broadly authorized enclave already holds unrestricted
plaintext access to the address for an unrelated legitimate reason,
an output-only Finality Sink cannot retroactively undo profiling
computation that already occurred inside it. Access and computation
boundaries require enforcement at the point capability is granted,
not only at the point output is written.
5.6. A Request for a Derived Value
The advertising system instead attempts to write a value computed
from, but not textually identical to, the address:
customer-17 -> estimated high-income household
The value contains no street address. A Finality Sink that checks
only for the literal restricted value would pass it. A Finality Sink
that checks propagated source lineage does not:
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Derived object: income-estimate-52
Restricted source: address-619
Requested use: advertising
The profile-write boundary rejects the write on the lineage binding,
not on pattern-matching the output. This requires deliberate, non-
removable tracking of derived-data provenance; a label attached to
the output that the producing workload can choose to omit provides no
enforcement at all.
5.7. What This Architecture Does Not Close
If an authorized courier receives the plaintext address and copies it
into an unrelated application, the protected data service cannot
guarantee the copy is never reused. Containment beyond this point
requires controlled recipient software, restricted export paths,
minimal disclosure, and downstream enforcement at the recipient's own
boundary -- outside what a source-side PED can observe. Human
observation, screenshots, and compromised endpoints remain outside
this architecture's reach. The claim this document makes is
therefore bounded: within an enforced system boundary, data can be
made unavailable to unauthorized workloads, and unauthorized derived-
value writes can be blocked. Preventing every possible reuse after
legitimate plaintext disclosure is a different, and materially
harder, problem that this document does not claim to solve.
6. Threat Model
In scope:
* A requester relabels or forges the purpose field of a request to
obtain access to data it is not authorized to use for that purpose
(Section 5.4).
* A requester assumes that running inside an attested TEE
substitutes for a purpose-authorization check (Section 5.5).
* A requester attempts to obtain a value derived from restricted
data as a way of evading a restriction on the source value
(Section 5.6).
* A requester replays a validly issued Execution Handle from a
different workload identity or toward a different destination than
the one it was scoped to.
Out of scope / residual risk:
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* Reuse of data after legitimate plaintext release to an authorized
recipient (Section 5.7).
* Compromise of the Protected Enforcement Domain itself, or of the
binding records it evaluates against; this architecture assumes
the PED and its record store are not themselves attacker-
controlled.
* Side-channel or covert-channel exfiltration from within an
authorized, attested computation.
7. Relation to Existing Work
The pattern of checking a request's declared purpose against a policy
before granting access is not new in the access-control literature;
purpose-based access control (PBAC) models and attribute-based access
control frameworks such as XACML define policy evaluation over
request attributes including purpose. This document's distinguishing
element is that the evaluated attributes are drawn from binding
records external to the request (order state, recipient assignment,
workload identity), the resulting grant is a short-lived, non-bearer,
single-scope Execution Handle rather than a general session grant,
and derived-value writes are checked against propagated source
lineage rather than against the presence or absence of a purpose
label on the output.
Decentralized information flow control (DIFC) systems address the
derived-data problem in Section 5.6 by propagating labels through
computation at the operating-system or language-runtime level. This
document does not specify a label-propagation mechanism; it specifies
that a Finality Sink MUST reject a derived-value write that cannot
demonstrate valid source lineage, leaving the propagation mechanism
to the implementing system.
[RFC8707] (Resource Indicators for OAuth 2.0) and audience
restriction in OAuth 2.0 bearer tokens address a related but narrower
problem: binding a token to an intended resource server. This
document's Execution Handle extends that idea to bind a grant to a
specific operation and destination, evaluated per Candidate Act
rather than issued once per session.
8. Relevance to IETF Working Groups
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8.1. GNAP
GNAP [RFC9635] already separates the negotiation of a grant from its
use, and supports fine-grained, per-request access rather than a
single broad session token. The Execution Handle described here is
compatible with a GNAP access token scoped to a single resource/
operation pair; this document's contribution to GNAP-adjacent work is
the requirement that the Authorization Server's grant decision be
made against externally-verified binding records rather than against
client-supplied purpose or context claims, and that a derived-
resource request be evaluated against source lineage rather than
treated as a fresh, unrelated grant.
8.2. OAUTH
OAuth 2.0 [RFC6749] deployments that rely on a "purpose" or "scope"
string supplied by the client are exposed to exactly the relabeling
attack in Section 5.4. [RFC8707]'s audience restriction is a partial
mitigation already in the OAuth toolkit; this document suggests that
audience restriction alone is insufficient where the threat model
includes a legitimately audience-scoped token presented for an
operation outside its intended purpose, and that purpose SHOULD be a
property the authorization server derives from verifiable request
context rather than a bearer-supplied claim.
8.3. RATS
Section 5.5 is directly a RATS-relevant finding: this document treats
a RATS [RFC9334] Attestation Result as answering "is this code
running as expected" and treats purpose/operation authorization as a
separate, subsequent check that a Relying Party MUST perform
independently. Where RATS-based systems are used to gate access to
sensitive data, this document's caution against conflating
attestation with authorization is offered as an applicability
consideration.
8.4. SPICE
SPICE's work on credential formats and selective disclosure is
relevant to Section 5.1's binding of a data object to a specific
permitted workflow: a credential-based encoding of the "allowed
workflow / allowed operation / allowed recipient" policy record would
let the binding travel with the data object in a verifiable form
rather than living only in a centralized policy store, which may be
of interest to SPICE's scope on interoperable credential structures.
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8.5. SECDISPATCH
This document is submitted as an individual architectural pattern
rather than a protocol specification, and the author does not assert
a specific IETF venue for standardization. SECDISPATCH is the
appropriate venue to determine whether, and where, a purpose-binding
and derived-data-lineage mechanism of this kind warrants protocol-
level standardization versus remaining an architectural pattern
referenced by implementers of GNAP, OAuth, and RATS-based systems.
8.6. PEARG (IRTF)
The Privacy Enhancements and Assessment Research Group is an IRTF
research group rather than an IETF working group, and is noted here
because Section 3.3 and Section 5.6 (derived-data lineage) and
Section 5.7 (the residual plaintext-reuse limit) are research
questions as much as engineering ones; PEARG's work on privacy threat
modeling and assessment methodology is relevant to evaluating how
completely a lineage-propagation mechanism actually closes the
derived-data gap in practice.
9. Security Considerations
The security of this architecture reduces to the integrity of the
Protected Enforcement Domain and the binding records it evaluates
against. An attacker who can write to the order-management record,
the courier-assignment record, or the policy-version store used in
Section 5.2 can forge a passing evaluation without needing to
compromise the PED's logic itself; those records MUST be integrity-
protected to a standard at least as strong as the PED's own decision
logic. Execution Handles MUST be short-lived, single-scope, and non-
bearer (i.e., bound to and unusable outside the requester identity
and destination they were issued for) to limit the value of a
captured handle. LAVR generation on both pass and fail outcomes is
REQUIRED so that a rejected Candidate Act is not silently dropped in
a way that hides a probing attack pattern.
10. Privacy Considerations
This architecture is itself a privacy control, but it introduces its
own data: the PED's binding records, and the LAVR trail, together
describe who requested what data for what purpose and when. That
record is sensitive in its own right and access to it SHOULD be
governed by the same purpose-binding discipline described in this
document, to avoid recreating the original problem one layer up.
Implementations SHOULD apply data minimization to LAVR contents --
recording that a check passed or failed and against which policy
version, rather than the full content of the Candidate Act, where the
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Candidate Act's content is itself sensitive.
11. IANA Considerations
This document has no IANA actions.
12. Intellectual Property and Licensing
This document describes an architectural pattern that is part of a
broader execution-finality patent portfolio pursued by the author.
This document, and the accompanying reference material referenced in
Section 18, are made available under CC BY-NC 4.0 by default. Patent
rights in the underlying architecture are reserved and are not
licensed by publication of this document. If any element described
in this document is incorporated into an IETF Standards Track
specification, the author intends to offer licensing on Fair,
Reasonable, and Non-Discriminatory (FRAND) terms consistent with the
IETF's IPR disclosure obligations under [BCP79].
13. Acknowledgments
None yet.
14. Resources
[DAS-EU-AI-ACT] and [DAS-GLOBAL-PRIVACY] develop the execution-
enforcement model summarized in this document in greater technical
detail, including Candidate Acts, protected validation, scoped non-
bearer authority, Finality Sink enforcement, and privacy and
jurisdictional controls, together with deployment considerations not
repeated here. Readers interested in the protocol mechanics are
encouraged to review those drafts alongside
[DAS-PRIVACY-FINALITY-IMPL], a runnable reference implementation of
the privacy/purpose-enforcement path described in Section 5.
[DAS-PRIVACY-FINALITY-IMPL]'s built-in demo enforces GDPR Article
5(1)(b) purpose limitation and AI Act-style technical enforcement
obligations as one concrete instance of the general mechanism
specified in this document. The demo models a customer support
request scoped to CUSTOMER_SUPPORT (delivery_status,
expected_delivery_date) and denies a resubmission of the same request
under TARGETED_MARKETING before any Finality Sink effect is recorded
-- the same Candidate Act / Protected Enforcement Domain / Finality
Sink pattern this document describes, in regulation-agnostic form, as
the delivery-address / advertising-profiling example in Section 5.
The mapping between the two is direct:
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+====================================+=============================+
| Reference implementation | This document |
+====================================+=============================+
| Candidate Act (canonical JSON, | Candidate Act (Section 2) |
| SHA-256 digest) | |
+------------------------------------+-----------------------------+
| Protected Enforcement Domain (PED) | Protected Enforcement |
| | Domain (Section 2) |
+------------------------------------+-----------------------------+
| Signed act-bound Validation Permit | Execution Handle, non- |
| + workload proof-of-possession | bearer, scoped (Section 2) |
+------------------------------------+-----------------------------+
| Finality Sink (independent re- | Finality Sink (Section 2) |
| verification) | |
+------------------------------------+-----------------------------+
| Denied TARGETED_MARKETING | Section 5.4, relabeled / |
| substitution | purpose-substituted request |
+------------------------------------+-----------------------------+
Table 2: Mapping between the reference implementation and this
document
GDPR and the EU AI Act are the regulatory framing the reference
implementation was built to demonstrate; the enforcement mechanism
itself, as specified in this document, is regulation-agnostic and
does not depend on any one jurisdiction's law.
[DAS-PRIVACY-FINALITY-IMPL] explicitly disclaims that it decides
whether a purpose is legally legitimate, whether consent is valid, or
whether a controller satisfies any specific data-protection statute;
it enforces machine-readable rules supplied to it, which is the same
scope this document claims for the architecture in Section 4.
15. Latency Characteristics (Non-Normative)
This section reports measured, not projected, latency for the
[DAS-PRIVACY-FINALITY-IMPL] reference implementation's three
sequential stages -- PED validation (Section 5.2's checks), permit
issuance plus workload proof-of-possession (the Execution Handle of
Section 2), and Finality Sink verify-and-commit (the atomic effect
record of Section 4) -- each timed within a single request iteration
so the three figures compose into one end-to-end path, at 500
iterations, on the SME support-agent demo Candidate Act. Two runs are
reported: the implementation's own published figures, and an
independent re-run performed for this document on different hardware,
as a sanity check rather than a replacement measurement.
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+=================+==========================+====================+
| Stage | Published median/p95/p99 | Independent re-run |
| | | median/p95/p99 |
+=================+==========================+====================+
| PED validation | 21.5 / 33.1 / 118.9 | 31.2 / 52.4 / 65.9 |
+-----------------+--------------------------+--------------------+
| Permit + PoP | 95.1 / 145.1 / 338.1 | 120.1 / 154.0 / |
| | | 190.5 |
+-----------------+--------------------------+--------------------+
| Sink verify + | 271.4 / 371.9 / 499.7 | 335.4 / 385.9 / |
| commit | | 459.9 |
+-----------------+--------------------------+--------------------+
| End-to-end (sum | ~388.0 | ~486.7 |
| of medians) | | |
+-----------------+--------------------------+--------------------+
Table 3: PED / permit / sink latency, published vs. independent
re-run (microseconds)
Two observations follow directly from the data. First, the Finality
Sink's atomic commit step (SQLite BEGIN IMMEDIATE plus unique-JTI
replay check) dominates the total in both runs -- roughly 60-70% of
end-to-end median latency -- not the cryptographic verification steps
(signature check, proof-of-possession). This is consistent with the
general expectation that the fail-closed, atomic finality boundary of
Section 4 is the more expensive operation to make correct, not the
identity or purpose checks upstream of it. Second, both runs land
the end-to-end path under half a millisecond, which is the basis for
describing this as a hot-path-suitable operation for interactive
request/response flows, subject to Section 16's caveats about the
sink's storage backend.
As stated directly in the reference implementation and repeated here:
this is a local Python microbenchmark on a single process, not a
distributed-system or network-inclusive measurement, and it is NOT a
protocol performance claim. It excludes network round-trip time
between requester, PED, and Finality Sink when these run as separate
services; excludes the cost of the binding-record lookups in
Section 5.2's check table (the demo's vaults are in-process, not a
networked identity/order/policy store); and excludes concurrency
effects -- SQLite's single-writer model means throughput, not just
per-request latency, is the binding constraint at production scale
(see Section 16). A deployment claiming this latency profile MUST
re-measure against its own storage backend, network topology, and
binding-record sources before relying on these figures.
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16. Feasibility and Legacy System Integration
*Deployment topology.* The PED, the Execution Handle issuer, and the
Finality Sink are logically separable and MAY run as one process, as
a sidecar per protected service, or as independently administered
services (a pattern already anticipated by
[DAS-PRIVACY-FINALITY-IMPL]'s note that vaults/PED/sink state can
move into separate processes, TEEs, HSMs, confidential VMs, or DPUs/
SmartNICs). The architecture is agnostic to which topology an
adopter chooses; Section 15's figures were measured in-process and
should be treated as a floor, not a ceiling, once a real network hop
separates these components.
*Cold path / hot path split.* Companion draft draft-das-execution-
finality-protocol-layer-00 separates policy reasoning (which bindings
apply, which policy version is current) from deterministic
verification (does this specific Candidate Act satisfy those
bindings). The former can be cached, precomputed, or evaluated
asynchronously as records change; the latter is what Section 15
measures and is designed to stay on the interactive request path.
Implementers SHOULD keep policy lookups (the "cold" work) out of the
per-request hot path so that the Finality Sink's atomic commit
remains the dominant, and only, per-request cost.
*Throughput and storage backend.* The reference implementation's
SQLite-backed replay/effect store uses a single-writer commit model;
at the measured ~330-490 us per commit, a single Finality Sink
instance backed by SQLite is bounded to roughly two to three thousand
committed effects per second before write contention dominates. This
is adequate for the SME demo's scale and NOT representative of a
production deployment's requirements; a production Finality Sink
SHOULD replace the single-writer store with a backend that supports
concurrent atomic commit with equivalent replay-prevention guarantees
(e.g., a transactional database cluster or an append-only ledger with
unique-nonce enforcement), and MUST preserve the fail-closed, atomic-
consume property of Section 5.2 when doing so -- a faster backend
that weakens atomicity reintroduces the race this architecture exists
to close.
*Legacy system integration without a flag day.* This architecture is
intended to be adopted incrementally, not as a wholesale replacement
of existing access control:
* It SHOULD be deployed as an additional enforcement point
positioned at or behind an existing API gateway, service mesh, or
authorization layer (OAuth, GNAP, internal ABAC), not as a
replacement for those systems. Coarse-grained authentication and
general access control continue to run unchanged; this
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architecture adds a finer-grained, purpose-and-lineage-aware check
at the specific data objects and operations an adopter chooses to
protect.
* Adoption SHOULD proceed data-object-class by data-object-class. A
newly protected class (e.g., delivery addresses, as in Section 5)
is bound to policy and enforced from the moment it is onboarded;
classes not yet onboarded continue to be served by whatever legacy
access control already governs them.
* An unmigrated resource MUST NOT be represented, in logs,
dashboards, or documentation, as being under this architecture's
enforcement. A resource with no binding record is not
"permissively allowed" by this architecture -- it is simply
outside its scope, and an adopter that fails to mark that
distinction risks the false sense of security this document argues
against in Section 3.1.
* No retroactive protection is created for data already released
under a legacy regime before onboarding. Section 5.7's residual
limitation applies identically here: onboarding a data class going
forward does not constrain copies already made under the prior
regime.
*Real-time bidding and other latency-constrained environments.* Real-
time bidding (RTB) in programmatic advertising operates within an
auction window commonly on the order of 100 milliseconds end-to-end
across multiple participants (supply-side platform, ad exchange, and
one or more demand-side platforms). This is among the tightest
latency budgets this architecture might be applied to and deserves
direct treatment rather than a general feasibility claim.
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Cross-referencing data across advertising systems -- combining
signals from multiple sources to select or price an ad -- is a
legitimate, economically load-bearing function of the industry and is
not, by itself, the problem this document addresses. The problem is
unauthorized cross-referencing: a system consuming a signal for a use
it was never granted, the same reuse pattern illustrated with
delivery data in Section 5.3. Removing an advertising system's
ability to combine data in order to make it "safe" would eliminate
the function the system exists to perform and would stall a
significant share of the economic activity the industry depends on;
that is not this document's goal. The goal is to make an authorized
combination technically demonstrable, and an unauthorized one
technically blocked, rather than leaving the boundary between the two
resting entirely on a data-sharing agreement that no downstream
system actually checks -- this architecture is offered as a way to
make lawful cross-referencing verifiable, not as a way to stop cross-
referencing.
Whether this is achievable inside a 100ms RTB budget is a question of
where in the bid path enforcement is placed, not whether enforcement
is possible at all:
* A per-bid Candidate Act evaluated against a live policy store,
with a TEE remote-attestation round-trip inline in the bid path,
is not compatible with a 100ms budget; the attestation handshake
alone commonly consumes a large share of that budget on its own,
independent of anything measured in Section 15.
* Section 15's measurements (sub-millisecond PED validation, permit
issuance, and Finality Sink commit) are achievable in-path only if
the expensive part -- deciding whether a given combination of data
sources is authorized for a given advertiser/publisher/purpose
triple -- is treated as cold-path work, evaluated and cached well
before any individual bid, and refreshed on a policy change rather
than on every auction. What remains in the 100ms hot path is then
the cheap, deterministic step: verifying that this bid's Candidate
Act matches an already-issued, still-valid Execution Handle for
this exact combination -- the sub-millisecond range Section 15
measured, not a fresh policy evaluation or a fresh attestation.
* Under this split, the architecture does not ask an RTB system to
slow its auction down to perform compliance work live; it asks the
system to be able to produce, on demand, a verifiable record that
a specific data combination used in a specific bid was covered by
a specific, current authorization -- which is close to what a
regulator asking for evidence of purpose-limitation compliance is
already asking advertising companies to be able to produce,
typically without machine-checkable evidence to offer today.
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An implementer that attempts to fit full live policy evaluation and
attestation into the per-bid path will fail the latency budget and
should not attempt to. An implementer that separates authorization
(cold, cacheable, amortized across many bids) from verification (hot,
sub-millisecond, per bid) has a credible path to a compliance record
without materially affecting auction latency -- and a credible,
auditable basis for arguing that its cross-referencing practice is
lawful, rather than merely asserted to be.
*Feasibility summary.* The mechanism itself -- Candidate Act,
binding-record check, scoped Execution Handle, atomic Finality Sink
commit -- is implementable with commodity components (a policy/record
store, an Ed25519 signing service, and a transactional commit
boundary) and does not require new hardware, though Section 5.5 notes
that hardware-rooted attestation strengthens, without being required
by, the workload-identity leg of Section 5.2's checks. The primary
adoption cost is organizational rather than cryptographic:
identifying which binding records (order state, recipient assignment,
workload identity) an adopter's systems already maintain reliably,
versus which must be newly built, since the PED's validity depends
entirely on the trustworthiness of the records it checks against
(Section 9).
17. Normative References
[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/info/rfc2119>.
[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/info/rfc8174>.
18. Informative References
[BCP79] IETF, "Intellectual Property Rights in IETF Technology",
BCP 79, <https://www.rfc-editor.org/info/bcp79>.
[DAS-EU-AI-ACT]
Das, S., "Technical Execution Enforcement for the EU AI
Act", Work in Progress, <https://datatracker.ietf.org/doc/
draft-das-eu-ai-act-execution-enforcement/>.
[DAS-GLOBAL-PRIVACY]
Das, S., "Global Privacy Execution Enforcement", Work in
Progress, <https://datatracker.ietf.org/doc/draft-das-
global-privacy-execution-enforcement/>.
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[DAS-PRECISION-EGRESS]
Das, S., "Precision-Bounded Egress", Work in Progress,
<https://datatracker.ietf.org/doc/draft-das-precision-
bounded-egress/>.
[DAS-PRIVACY-FINALITY-IMPL]
Das, S., "Privacy Finality Reference Implementation",
GitHub repository,
<https://github.com/sangmdas/privacy-finality-reference>.
[FUTURIUM-PAPER-COMPLIANCE]
Das, S., "From Paper Compliance to Technical Enforcement:
Making GDPR and the EU AI Act Executable in the AI Era",
EU AI Alliance Futurium,
<https://futurium.ec.europa.eu/en/apply-ai-alliance/posts/
paper-compliance-technical-enforcement-making-gdpr-and-eu-
ai-act-executable-ai-era>.
[FUTURIUM-PURPOSE-LAUNDERING]
Das, S., "Preventing Data-Purpose Laundering by Agentic
AI: A Hardware-Rooted Pre-Effectuation Layer for GDPR
Purpose Limitation and High-Risk AI Governance", EU AI
Alliance Futurium, <https://futurium.ec.europa.eu/en/
apply-ai-alliance/community-content/preventing-data-
purpose-laundering-agentic-ai-hardware-rooted-pre-
effectuation-layer-gdpr-purpose>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[RFC8707] Campbell, B. and A. Bansal, "Resource Indicators for OAuth
2.0", RFC 8707, DOI 10.17487/RFC8707, February 2020,
<https://www.rfc-editor.org/info/rfc8707>.
[RFC9334] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/info/rfc9334>.
[RFC9635] Richer, J. and F. Imbault, "Grant Negotiation and
Authorization Protocol (GNAP)", RFC 9635,
DOI 10.17487/RFC9635, October 2024,
<https://www.rfc-editor.org/info/rfc9635>.
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Author's Address
Sangam Kumar Das
Independent Inventor
Balasore
Odisha
India
Email: info@sangamdas.com
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