Verification Protocol

Every artifact published to the IMPP registry undergoes a multi-stage verification pipeline before receiving a signed certificate.

Ed25519 Certificate Format

Certificates are compact Ed25519 signatures over a canonical JSON representation of the artifact header. The header includes the artifact hash, domain, trust score, and expiry timestamp.

{
  "artifact_id": "defi-risk-assessment@v2.1",
  "domain": "defi",
  "trust_score": 94.2,
  "issued_at": "2026-04-24T10:00:00Z",
  "expires_at": "2026-07-24T10:00:00Z",
  "signature": "base64url(Ed25519_sig)",
  "pubkey": "base64url(registry_pubkey)"
}

Certificates expire after 90 days by default. Artifact owners can re-verify to issue a fresh certificate without re-publishing.

Adversarial Probe Suite

Before issuance, artifacts are subjected to the following probes. A failing probe blocks certification.

Probe Details

Steganography Detection runs statistical analysis on the artifact content to detect unusual patterns that could encode hidden instructions or payloads. Uses KL-divergence against reference distributions for the artifact's content format.

Overfit Probe evaluates the artifact against held-out test sets from the same domain. An artifact that performs significantly better on its training distribution than on the test set is flagged.

Negative Transfer Probe attaches the artifact to a clean baseline agent and measures task performance before and after. A statistically significant drop in baseline tasks indicates negative transfer.

Freshness Check compares the artifact's source data timestamps against domain-specific thresholds. DeFi artifacts with data older than 30 days are flagged. Cybersecurity artifacts have a 90-day threshold. Freshness is computed using exponential decay with a configurable half-life (default 180 days).

Schema Integrity validates the IMPP artifact schema M = (D, K, P, A, H): required fields (domain, knowledge, provenance, attestation), version format, and content format constraints.

Adversarial Risk Thresholds

Each probe contributes to a composite adversarial risk score (0–100), weighted as follows:

The composite risk score determines the outcome:

Trust Score Computation

The trust score is a weighted composite of three signals:

trust_score = (
  0.50 * transfer_efficiency +
  0.30 * adversarial_clean +
  0.20 * freshness
)

Where:

• transfer_efficiency — how well the artifact's knowledge transfers to a receiving agent, measured as task performance improvement (0–100)
• adversarial_clean — 100 - adversarial_risk_score; higher means cleaner (0–100)
• freshness — exponential decay based on artifact age, with a 180-day half-life (0–100)

Scores range from 0 to 100. Artifacts below 50 are not certified.

Offline Verification

Certificates can be verified without network access using the bundled registry public key. The key is pinned in the CLI at install time and rotated annually.

$ impp verify artifact.json --offline --pubkey ~/.impp/registry.pub

The offline check validates:

1. Ed25519 signature over the canonical header
2. Certificate expiry timestamp
3. Artifact hash matches the signed hash

It does not re-run the adversarial probes (those require server-side infrastructure).