Audit network interactions
(Section: Ecosystem and Network)
1) Why do you need it
The audit of interactions ensures the provability of facts: who exchanged with whom what, when and in what state. This reduces the cost of proceedings, speeds up compliance checks, increases trust between participants and allows you to scale the network without "manual arbitration."
2) Scope and boundaries
Channels: synchronous RPC (REST/gRPC), webhooks, bus events, batches/files.
Artifacts: requests/responses, events and receipts, signatures, payload hashes, change logs.
Audit objects: business transactions (payment, game round, KYC verdict), technical actions (retrays, timeouts, redraw).
Boundaries: per-tenant, per-region, per-integration; aggregation at the global level.
3) Audit principles
1. Provability by default: critical messages are accompanied by signatures and receipts.
2. End-to-end correlation: single 'trace _ id '/' span _ id' for RPC, events, webhooks and batches.
3. Idempotency and reproducibility: deterministic replay capability.
4. Independent verification: Artifacts can be verified without trusting the provider.
5. Privacy and minimization: evidence instead of extra PII; tokenization and redaction.
6. Automation: Checks and reconciliations are done regularly and by machine.
4) Artifact model
Квитанция (Receipt): `{delivery_id, content_hash, occurred_at, producer, signature}`.
Event log: append-only, entries with 'event _ id', 'trace _ id', 'schema _ version', 'region', 'tenant'.
Signatures: for incoming/outgoing messages (mTLS + header/body signature).
Merkle-roots: periodic "slices" of the journal with the publication of the root and inclusion chains.
Schema catalog: stable versions of contracts (expand → migrate → contract).
5) End-to-end tracing
In each message: 'trace _ id', 'parent _ span _ id', 'idempotency _ key', 'request _ id'.
Context forwarding through: RPC → event bus → webhooks → batches.
For asynchronous processes: 'correlation _ id' + status endpoints (poll/push).
6) Signatures and anti-replay
Titles: 'signature', 'timestamp', 'nonce', 'delivery-id'.
Time tolerance window (TTL), repetition protection, blacklists of used'nonce '.
Rotation of keys and pinning of public keys of partners; storing trust chains.
7) Transparent logs (immutability)
Append-only with overwrite protection; periodic publication of the Merkle-root.
Inclusion/immutability check by "path proofs."
Domain separation: technical logs (high volume) and business logs (receipts).
8) Retention policies and privacy
Retention periods: by criticality levels (for example, payments - 7-10 years, telemetry - 30-90 days).
Localization: PII/financial data - only in the "zones of trust" of the region; in logs - hashes/tokens.
Right to be forgotten: the primary PII object is removed; the journal remains provable (hash/commit).
Data minimization: events carry identifiers/proofs, not "extra" attributes.
9) Auto checks and reconciliations
Webhook delivery arc: sending retray → → confirmation (2xx) → receiver receipt.
Consistency reconciliation: periodic comparisons of snapshots (Merkle-diff).
Quality alerts: growth of "rotten" 'nonce', divergence of hashes, replication lags, p95 signature verification time.
Regression-checks of contracts: validity of schemes, backward compatibility.
10) Proceedings (Dispute/Arbitration)
Subject of dispute: inconsistency of amounts/statuses, delay, double delivery, unavailability.
Evidence set: receipts of the parties, inclusion in the log (Merkle-path), signature, trace _ id.
Process: dispute registration → automatic verification of artifacts → verdict/compensation (escrow/SLA fines).
Arbitration SLO: target TTR (for example, ≤ 24-48 hours for critical cases).
11) Audit Metrics (SLO/SLI)
Critical flow bill coverage (%) and percentage of messages signed.
Signature/inclusion verification time (p95/p99).
Webhook delivery success and average retray lag.
Proportion of idempotently processed takes.
Number/percentage of incidents with a complete set of artifacts (evidence completeness).
TTR on disputes, share of automatic verdicts.
12) Dashboards
Contour of provability:% of signatures, validity, key rotation.
Delivery and retreats: heat maps of lags, retreats by integration/region.
Immutability: progress of Merkle-roots publications, success of external checks.
Disputes: statistics of causes, amounts, TTR, outcomes.
13) Organization and roles
Audit Owner: Responsible for artifact standards and accessibility.
Key guard (KMS/HSM): rotations, access policies, operation log.
Integration office: certification of contracts/webhooks, "marketplace" of statuses.
Arbitration/compliance: independent review, keeping a register of disputes and verdicts.
14) Incident processes
Playbooks: loss of correlation, inauthentic signature, inhibitory receiver of webhooks, "retray storm."
Degradation according to plan: frequency reduction, switching to batches/deferred operations, route pauses.
Postmortems: mandatory action items, evaluation of artifact coverage.
15) Tools and integrations
Trace: OpenTelemetry-compatible agents, export 'trace _ id' to logs and events.
Signature validation: validation services on Edge/API gateway, centralized key directory.
Journals: repositories with WORM semantics (write once, read many) and Merkle snapshots.
Contracts as code: SDK generation/schema validators, backward compatibility autotests.
16) Implementation checklist
1. Describe critical streams and mandatory artifacts (receipts, signatures, hashes).
2. Enter end-to-end 'trace _ id' and 'idempotency _ key' in all channels.
3. Implement signatures and anti-replay for webhooks; status endpoints.
4. Run append-only logs and publish Merkle roots at the specified frequency.
5. Set up auto-builds of snapshots and quality alerts.
6. Define retention periods, PII revision, and data localization.
7. Implement certification of integrations and regression-verification of contracts.
8. Create dashboards and SLO for audit; a bank of playbooks of incidents and disputes.
9. Train teams: how to form/check artifacts, how to conduct proceedings.
10. Conduct regular GameDays: "loss of correlation," "retray storm," "key compromise."
17) Risks and anti-patterns
"There are logs, but no evidence": no signature/receipt/hash.
The gluing of tracks is lost at the borders: the absence of 'trace _ id' in events/webhooks.
Extra PII in magazines: privacy violations and regulatory risks.
Unmanaged keys: no rotation and pinning → replay attack.
Lack of auto-checks: discrepancies are detected only "manually" and late.
18) Specificity for iGaming/fintech
Game outcomes: receipts "provably fair" (commit/signature/TEE-attestation) + writing to a transparent log.
Payments/payouts: bilateral receipts and reconciliation of registers (Merkle-diff), SLA-fines as code.
Affiliates/webhooks: HMAC + nonce, admission idempotency, status endpoints; reports - as signed snapshots.
CMC/risk: attestations/verifiable credits; keep evidence rather than the original PII.
19) FAQ
Do I need to sign everything? Sign critical streams and reference artifacts; hashes and correlation are sufficient for telemetry.
Where to store evidence? In WORM-compatible journals with Merkle slices; PII keep in "zones of trust."
How to reduce the load? Batch receipts, store hashes and links, not full payloads.
What is primary - logs or receipts? Receipts: They are compact and provable; logs - for detailing.
Summary: The audit of interactions is a system of provability, not just "logs." Standardize artifacts, ensure cross-cutting correlation and immutability of journals, automate reconciliations and proceedings. Then the network gets verifiability, quick response to incidents and predictable compliance when scaled by participants and regions.