AI Decision Evidence

What Is a Signed AI
Decision Certificate?

A signed AI decision certificate is the tamper-evident receipt for a single governed AI decision: the verdict, the policy version that produced it, and a digest of the inputs — bound together and signed so anyone can confirm, offline, that it is authentic and unaltered.

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The definition of the AI Decision Evidence category

The Definition

From dashboard claim to verifiable record

Most AI governance tools tell you a decision happened. A decision certificate lets you prove it — to an examiner, a regulator, or a counterparty who does not trust you.

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Structured & canonical

Each certificate is JCS-canonicalized (RFC 8785) so the exact bytes that were signed are reproducible. No ambiguity about what was attested.

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Signed at issue

The verdict, policy id, request digest and timestamp are signed the moment the decision is made — bound so a single altered field breaks verification.

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Hash-chained

Certificates link to the prior record by hash. Removing or reordering a decision is detectable: the chain no longer validates.

governed_decision_certificate.jsoneve.decision.certificate.v1

{
  "certificate_id": "gdc_8f31a0c4e9b7",
  "issued_at": "2026-06-20T14:08:21Z",
  "tenant_id": "org_acme",
  "policy_set": "lending_v1",
  "request_digest": "sha256:5c1f…a902",
  "decision": "BLOCKED",
  "reason_code": "ECOA.adverse_action.unexplained",
  "prev_hash": "sha256:0b77…1e4d",
  "signature": { "alg": "ed25519", "key_id": "eve-prod-2026", "value": "f3a1…b9c0" }
}

Anatomy

What each field proves

Field	What it is	What it proves
issued_at	UTC timestamp, signed inline.	When the decision was made — back-dating breaks the signature.
policy_set	The named, versioned policy that evaluated the action.	Exactly which rules were in force — the basis for replay.
request_digest	SHA-256 digest of the request.	Binds the decision to its inputs without storing raw or sensitive data.
decision	ALLOWED · BLOCKED · MODIFIED.	The governed outcome that actually reached the world.
reason_code	Structured, citable reason.	"Why," decided before the action — not a post-hoc rationalization.
prev_hash	Hash of the prior certificate.	Tamper-evidence: removing or reordering a decision breaks the chain.
signature	Ed25519 signature, alg, key id.	Authenticity + integrity, verifiable with the public key alone.

What It Is Not

A certificate is not a log line

A traditional audit log is a record you ask others to trust. A decision certificate is a record they can check for themselves. The difference is not cosmetic:

A log can be edited by anyone with write access; a certificate cannot be altered without breaking its Ed25519 signature.
A log proves nothing about why a decision was made; a certificate carries the policy version and reason code, decided before the action.
A log requires the vendor to still exist and cooperate; a certificate verifies with a public key and stock crypto, forever.

See the full contrast on Logs vs. Dashboards vs. Cryptographic Evidence.

Keep Reading

Guide

How It Works

Decide → sign → chain → aggregate → verify.

Verification

Offline Verification

Confirm a certificate without trusting the vendor.

Audit

Evidence Packs

Bundle certificates into a portable, examiner-ready artifact.

See a real certificate verify

Verify a live decision certificate in your browser — then hand the evidence to your own auditor and watch them verify it without us.

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