BAINK Evidence Standardv0.1 — draftApache-2.0

Open evidence infrastructure for AI-assisted banking decisions.

BAINK is a free, open protocol for creating tamper-evident, source-linked, policy-bound evidence bundles around AI-assisted credit, fraud, compliance, and servicing workflows.

Run locally. Verify independently. No SaaS account required.

$ baink verify ./credit_memo_bundle --profile baink-cm-0.1
Status: PASS WITH WARNINGS

PASS  artifact_hashes_match
PASS  event_hash_chain_valid
PASS  material_claims_supported
PASS  policy_versions_present
PASS  reviewer_signoff_present
WARN  one low-materiality claim lacks source span

01 — What BAINK is

The evidence layer underneath AI-assisted banking work.

BAINK is not another AI governance dashboard. It defines a portable evidence bundle that records exactly what happened around a decision.

  • what decision was made
  • what sources were used
  • what claims were generated
  • what policies applied
  • what model participated
  • who reviewed the output
  • what exceptions existed
  • what changed
  • who signed off
  • whether the record verifies

The result is a decision record that is reconstructable, tamper-evident, and independently checkable.

02 — The Free Evidence Layer

Free and open by design.

The base BAINK Evidence Layer is free because trust infrastructure needs independent verification.

ComponentPurpose
BAINK Evidence StandardOpen protocol specification
BAINK Bundle FormatPortable evidence package
BAINK-CM-0.1 ProfileCredit memo evidence profile
Rust Reference VerifierLocal verification engine
JSON SchemasInteroperable object definitions
Test VectorsValid and invalid bundle examples
CLI ToolLocal inspection and verification

BAINK should be as easy to run as a linter and as serious as an audit artifact.

03 — Why it exists

Plausibility is not defensibility.

A credit memo, fraud escalation, servicing response, or compliance review is not defensible because an AI system generated a plausible answer. It is defensible only if the institution can prove the receipts.

  • PASSthe source documents were known
  • PASSthe claims were linked to evidence
  • PASSthe applicable policies were versioned
  • PASSunsupported material claims were flagged
  • PASShuman review happened where required
  • PASSexceptions were dispositioned
  • PASSthe final decision record was sealed
  • PASSthe evidence can be independently verified

04 — How it works

Seven steps from input to verifiable record.

  1. 01Sources are hashed.
  2. 02AI-generated outputs are decomposed into claims.
  3. 03Claims are linked to sources, calculations, policies, or reviewer judgment.
  4. 04Events are written to an append-only hash chain.
  5. 05A BAINK bundle is generated.
  6. 06The bundle is verified locally.
  7. 07A verification report is emitted.
cli
$ baink verify ./loan_123_bundle --profile baink-cm-0.1
verification report
BAINK Verification Report
Bundle: loan_123
Profile: BAINK-CM-0.1
Status: PASS WITH WARNINGS

PASS  artifact_hashes_match
PASS  event_hash_chain_valid
PASS  material_claims_supported
PASS  policy_versions_present
PASS  reviewer_signoff_present
WARN  one low-materiality claim lacks source span
event #1
source_received
hash 0xbcd72fe8
event #2
claim_generated
hash 0x6cf16463
event #3
policy_test_passed
hash 0x4ffdff40
event #4
review_completed
hash 0xeb838fef
event #5
decision_recorded
hash 0xa331cdce

Each event embeds the previous event's hash. Removing, editing, or reordering an event breaks every later fingerprint.

05 — Protocol layers

Five layers, cleanly separated.

The base protocol defines the evidence grammar. Profiles define what a specific banking workflow requires.

Read the full standard →
L5
ProfilesCredit memo, fraud, AML, servicing, vendor review
L4
Verification RulesRequired artifacts, support rules, signoff rules, failure modes
L3
Evidence Bundle FormatPortable directory or archive with manifest, logs, maps, reports
L2
Primitive Object SchemasDecision, Source, Claim, Policy, Actor, Event
L1
Cryptographic IntegrityCanonical JSON, hashes, signatures, hash chains

The thesis

Every AI-assisted banking decision should be reconstructable, source-linked, policy-bound, role-approved, tamper-evident, and independently verifiable.