Attested checkout compliance gateway with payment-credential confinement, transaction-scoped evidence bundles, and fail-closed purchase control
An attested checkout gateway interposes a checkout sidecar before a merchant checkout interface to classify purchase-request fields and prevent primary account number data and sensitive authentication data from being processed by a merchant application process. A payment execution enclave within a trusted compute boundary verifies remote attestation before unsealing a payment credential, confines credential use to the trusted compute boundary, and generates a network-routable payment instrument while enforcing non-export of primary account number data and sensitive authentication data. A data-flow confinement digest is computed from measured confinement inputs. Responsive to evaluation under an applicable policy profile, the gateway either obtains step-up authentication evidence or generates a signed policy-evaluation record. A digitally signed compliance evidence bundle binds an attestation measurement, the data-flow confinement digest, an authorization trace digest, and the authentication evidence or signed policy-evaluation record, and fail-closed control blocks purchase completion or settlement when required trust conditions are unmet.
1 . A computer system comprising one or more processors and a non-transitory memory storing instructions that, when executed by the one or more processors, cause the computer system to implement an attested checkout compliance gateway comprising a checkout sidecar, a payment execution enclave, a confinement controller, a step-up authentication orchestrator, a compliance evidence bundle generator, a compliance exporter, and a policy enforcement controller, wherein execution of the instructions causes the attested checkout compliance gateway to perform operations comprising:
(a) intercepting, by the checkout sidecar deployed in front of a merchant checkout interface, a purchase request, classifying purchase-request fields, and withholding from a merchant application process any field classified as primary account number data or sensitive authentication data;
(b) performing, by the payment execution enclave operating inside a trusted compute boundary selected from the group consisting of a trusted execution environment (TEE), a hardware security module (HSM), and a combination thereof, operations comprising:
(i) verifying remote attestation of the trusted compute boundary, including comparing a reported measurement to an expected measurement referenced by a policy manifest, a version manifest, or an equivalent trust-policy object, prior to unsealing a payment credential;
(ii) unsealing the payment credential only within the trusted compute boundary and denying unseal upon attestation failure, mismatch, or revocation; and
(iii) generating or obtaining, within the trusted compute boundary, a network-routable payment instrument derived from the payment credential while enforcing an egress policy that forbids export of primary account number data and sensitive authentication data outside the trusted compute boundary;
(c) computing, by the confinement controller and for the purchase, a data-flow confinement digest from at least a measured egress policy digest and a process-boundary classification digest, the process-boundary classification digest identifying processes authorized to access the payment credential;
(d) responsive to evaluation under an applicable policy profile, either:
(i) perform step up authentication and obtain machine verifiable authentication evidence comprising at least an authentication result code and a cryptographic verifier output of signature bound to a canonical representation of an authentication transcript; of performing, by the step-up authentication orchestrator, step-up authentication and obtaining machine-verifiable authentication evidence comprising at least an authentication result code and a cryptographic verifier output or signature bound to a canonical representation of an authentication transcript; or
(ii) generating, by the step-up authentication orchestrator, a signed policy-evaluation record cryptographically bound to a canonicalized purchase context and indicating that step-up authentication was not required for the purchase;
(e) constructing, by the compliance evidence bundle generator, a Compliance Evidence Bundle (CEB) comprising at least:
(i) an attestation measurement associated with the trusted compute boundary used for the purchase,
(ii) the data-flow confinement digest,
(iii) an authorization trace digest binding an authorization outcome to a canonicalized purchase context that excludes primary account number data and sensitive authentication data, and
(iv) either the machine-verifiable authentication evidence or the signed policy-evaluation record, and digitally signing the CEB with a key protected by the trusted compute boundary over a signature scope that includes at least a transaction identifier or nonce, the attestation measurement, the data-flow confinement digest, and the authorization trace digest;
(f) outputting, by the compliance exporter, an auditor-mode CEB and a selective-disclosure CEB view that redacts personal data while preserving verifiability of at least the attestation measurement, the data-flow confinement digest, the authorization trace digest, and the machine-verifiable authentication evidence or the signed policy-evaluation record; and
(g) asserting, by the policy enforcement controller, fail-closed behavior and blocking settlement submission, merchant-side purchase completion, or both, when remote attestation fails, when export of primary account number data or sensitive authentication data outside the trusted compute boundary is detected, when required machine-verifiable authentication evidence is absent or invalid, or when step-up authentication is not required and the signed policy-evaluation record is absent or invalid.
2 . The system of claim 1 , wherein the checkout sidecar terminates mutually authenticated transport, enforces an allow-list of egress endpoints for payment processing, and forwards to the merchant application process only a non-sensitive derivative of the purchase request in which any field classified as primary account number data or sensitive authentication data is removed or replaced with a tokenization surrogate.
3 . The system of claim 1 , wherein the network-routable payment instrument comprises at least one of a network token, a tokenization surrogate, and a payment cryptogram generated within the trusted compute boundary.
4 . The system of claim 1 , wherein the data-flow confinement digest is further computed from a memory-access audit digest generated within the trusted compute boundary.
5 . The system of claim 1 , wherein the compliance exporter outputs a scope-reduction certificate comprising:
(i) a signed assertion indicating that the merchant application process did not store, process, or transmit primary account number data and that sensitive authentication data was not exported to the merchant application process; and
(ii) verifiable references to the attestation measurement and the data-flow confinement digest, wherein the signed assertion is generated based at least on the attestation measurement, the data-flow confinement digest, and at least one of the measured egress policy digest, the process-boundary classification digest, or a memory-access audit digest generated within the trusted compute boundary.
6 . The system of claim 1 , wherein, when step-up authentication is performed using a three-domain secure (3DS) protocol, the machine-verifiable authentication evidence includes at least one of an issuer-signed result, a directory-server signed result, and an access-control-server signed result bound to a 3DS transaction identifier.
7 . The system of claim 1 , further comprising a point-of-sale device having a secure element, wherein the network-routable payment instrument comprises an EMV authorization cryptogram generated by the secure element, and wherein the authorization trace digest binds the EMV authorization cryptogram to the canonicalized purchase context.
8 . The system of claim 1 , wherein the operations further comprise caching, by the compliance exporter, an auditor-mode CEB locally in an offline mode and later exporting, by the compliance exporter, the auditor-mode CEB upon reconnection, the auditor-mode CEB including an offline indicator and a bounded time window for offline validity.
9 . The system of claim 1 , wherein the operations further comprise outputting, by the compliance exporter, a dispute-ready evidence view that includes the authorization trace digest and, in a form usable for chargeback rebuttal and fraud investigation, either (i) machine-verifiable authentication evidence when step-up authentication is performed or (ii) a signed policy-evaluation record when step-up authentication is not required.
10 . The system of claim 1 , wherein verifying remote attestation comprises verifying an endorsement chain for an attestation key, checking revocation status, and comparing the reported measurement to an expected measurement referenced by the policy manifest, the version manifest, or the equivalent trust-policy object.
11 . A computer-implemented method comprising:
(a) intercepting, at a checkout sidecar deployed in front of a merchant checkout interface, a purchase request, classifying purchase-request fields, and withholding from a merchant application process any field classified as primary account number data or sensitive authentication data;
(b) verifying remote attestation of a trusted compute boundary, including comparing a reported measurement to an expected measurement referenced by a policy manifest, a version manifest, or an equivalent trust-policy object, prior to unsealing a payment credential; unsealing the payment credential only within the trusted compute boundary; and denying unseal upon attestation failure, mismatch, or revocation;
(c) generating or obtaining, within the trusted compute boundary, a network-routable payment instrument derived from the payment credential while enforcing an egress policy that forbids export of primary account number data and sensitive authentication data outside the trusted compute boundary;
(d) computing, for the purchase, a data-flow confinement digest from at least a measured egress policy digest and a process-boundary classification digest, the process-boundary classification digest identifying processes authorized to access the payment credential;
(e) responsive to evaluation under an applicable policy profile, either:
(i) performing step-up authentication and obtaining machine-verifiable authentication evidence comprising at least an authentication result code and a cryptographic verifier output or signature bound to a canonical representation of an authentication transcript; or
(ii) generating a signed policy-evaluation record cryptographically bound to a canonicalized purchase context and indicating that step-up authentication was not required for the purchase;
(f) constructing a Compliance Evidence Bundle (CEB) comprising at least an attestation measurement associated with the trusted compute boundary used for the purchase, the data-flow confinement digest, an authorization trace digest binding an authorization outcome to a canonicalized purchase context that excludes primary account number data and sensitive authentication data, and either the machine-verifiable authentication evidence or the signed policy-evaluation record, and digitally signing the CEB with a key protected by the trusted compute boundary over a signature scope that includes at least a transaction identifier or nonce, the attestation measurement, the data-flow confinement digest, and the authorization trace digest;
(g) exporting an auditor-mode CEB and a selective-disclosure CEB view that redacts personal data while preserving verifiability of at least the attestation measurement, the data-flow confinement digest, the authorization trace digest, and the machine-verifiable authentication evidence or the signed policy-evaluation record; and
(h) asserting fail-closed behavior and blocking settlement submission, merchant-side purchase completion, or both, when remote attestation fails, when export of primary account number data or sensitive authentication data outside the trusted compute boundary is detected, when required machine-verifiable authentication evidence is absent or invalid, or when step-up authentication is not required and the signed policy-evaluation record is absent or invalid.
12 . The method of claim 11 , wherein withholding sensitive payment credentials from the merchant application process comprises replacing a payment credential field with a tokenization surrogate before forwarding a non-sensitive derivative of the request for further merchant processing.
13 . The method of claim 11 , wherein the data-flow confinement digest is further computed from a memory-access audit digest generated within the trusted compute boundary.
14 . The method of claim 11 , wherein, when step-up authentication is performed, the step-up authentication comprises executing a 3DS authentication flow and obtaining machine-verifiable authentication evidence that includes a signed result bound to a 3DS transaction identifier.
15 . The method of claim 11 , wherein generating the network-routable payment instrument comprises generating an EMV authorization cryptogram within a secure element of a point-of-sale device and binding the EMV authorization cryptogram into the authorization trace digest.
16 . The method of claim 11 , further comprising producing a scope-reduction certificate comprising:
(i) a signed assertion indicating that the merchant application process did not store, process, or transmit primary account number data and that sensitive authentication data was not exported to the merchant application process; and
(ii) verifiable references to the attestation measurement and the data-flow confinement digest, wherein the signed assertion is generated based at least on the attestation measurement, the data-flow confinement digest, and at least one of the measured egress policy digest, the process-boundary classification digest, or a memory-access audit digest generated within the trusted compute boundary.
17 . The method of claim 11 , wherein verifying remote attestation comprises verifying an endorsement chain for an attestation key, checking revocation status, and comparing the reported measurement to an expected measurement referenced by the policy manifest, the version manifest, or the equivalent trust-policy object.
18 . The method of claim 11 , wherein exporting the selective-disclosure CEB view comprises redacting personal data fields while retaining verifiable digests for the canonicalized purchase context, the authorization trace digest, and the attestation measurement.
19 . The method of claim 11 , wherein the selective-disclosure CEB view includes a zero-knowledge proof attesting satisfaction of at least one policy predicate selected from an age threshold, a residency constraint, a spend-cap constraint, and a merchant-category constraint, without revealing underlying raw values.
20 . The method of claim 11 , wherein asserting fail-closed behavior comprises emitting a machine-readable failure record including a failure code selected from attestation_failure, minimization_violation, authentication_evidence_invalid, authentication_evidence_missing, policy_evaluation_record_invalid, and policy_evaluation_record_missing.
21 . A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause a computer system to:
(a) intercept, at a checkout sidecar deployed in front of a merchant checkout interface, a purchase request, classify purchase-request fields, and withhold from a merchant application process any field classified as primary account number data or sensitive authentication data;
(b) verify remote attestation of a trusted compute boundary, including comparing a reported measurement to an expected measurement referenced by a policy manifest, a version manifest, or an equivalent trust-policy object, prior to unsealing a payment credential; unseal the payment credential only within the trusted compute boundary; and deny unseal upon attestation failure, mismatch, or revocation;
(c) generate or obtain, within the trusted compute boundary, a network-routable payment instrument derived from the payment credential while enforcing an egress policy that forbids export of primary account number data and sensitive authentication data outside the trusted compute boundary;
(d) compute, for the purchase, a data-flow confinement digest from at least a measured egress policy digest and a process-boundary classification digest, the process-boundary classification digest identifying processes authorized to access the payment credential;
(e) responsive to evaluation under an applicable policy profile, either:
(i) perform step-up authentication and obtain machine-verifiable authentication evidence comprising at least an authentication result code and a cryptographic verifier output or signature bound to a canonical representation of an authentication transcript; or
(ii) generate a signed policy-evaluation record cryptographically bound to a canonicalized purchase context and indicating that step-up authentication was not required for the purchase;
(f) construct a Compliance Evidence Bundle (CEB) comprising at least an attestation measurement associated with the trusted compute boundary used for the purchase, the data-flow confinement digest, an authorization trace digest binding an authorization outcome to a canonicalized purchase context that excludes primary account number data and sensitive authentication data, and either the machine-verifiable authentication evidence or the signed policy-evaluation record, and digitally sign the CEB with a key protected by the trusted compute boundary over a signature scope that includes at least a transaction identifier or nonce, the attestation measurement, the data-flow confinement digest, and the authorization trace digest;
(g) export an auditor-mode CEB and a selective-disclosure CEB view that redacts personal data while preserving verifiability of at least the attestation measurement, the data-flow confinement digest, the authorization trace digest, and the machine-verifiable authentication evidence or the signed policy-evaluation record; and
(h) assert fail-closed behavior and block settlement submission, merchant-side purchase completion, or both, when remote attestation fails, when export of primary account number data or sensitive authentication data outside the trusted compute boundary is detected, when required machine-verifiable authentication evidence is absent or invalid, or when step-up authentication is not required and the signed policy-evaluation record is absent or invalid.
22 . The non-transitory computer-readable medium of claim 21 , wherein the instructions, when executed, further cause the computer system to terminate mutually authenticated transport, enforce an allow-list of egress endpoints for payment processing, and forward to the merchant application process only a non-sensitive derivative of the purchase request in which any field classified as primary account number data or sensitive authentication data is removed or replaced with a tokenization surrogate.
23 . The non-transitory computer-readable medium of claim 21 , wherein the data-flow confinement digest is further computed from a memory-access audit digest generated within the trusted compute boundary.