Continuous Trust Update Protocol

MolTrust CAEP Profile v1 — pending-events polling and registry-signed trust scores for adaptive agent authorization.

Overview

Trust scores in MolTrust change continuously: a Sybil flag fires, a new endorsement lands, an agent gets revoked. Verifiers (firewalls, agent runtimes, marketplaces) need a way to learn about those changes between their trust-score lookups so they can revoke a session, downgrade a permission, or refuse a tool call.

Profile v1 ships two channels:

• Pending events polling — a small endpoint per DID, default poll interval 30s. This is the stable v1 channel.
• Signed trust scores — every /skill/trust-score/{did} response now carries an Ed25519 signature over a deterministic JCS-canonicalized payload, so verifiers can cache and prove what the registry said at a given moment.

An XMTP-based push channel is on the roadmap for Q2/Q3 2026. Until then, polling is canonical.

Endpoints

curl https://api.moltrust.ch/caep/pending/did:moltrust:abc123

# With pagination cursor:
curl 'https://api.moltrust.ch/caep/pending/did:moltrust:abc123?limit=50&since=evt_a1b2c3d4e5f6g7h8'

curl -X POST https://api.moltrust.ch/caep/acknowledge/evt_a1b2c3d4e5f6g7h8

curl https://api.moltrust.ch/.well-known/registry-key.json
# {
#   "kid": "moltrust-registry-2026-v1",
#   "kty": "OKP",
#   "crv": "Ed25519",
#   "x":   "<base64url public key>",
#   "use": "sig",
#   "alg": "EdDSA"
# }

Event types

• trust_score_change — emitted when the cached score changes by ≥10 points. Payload: {old_score, new_score, delta, reason, computed_at}.
• flag_added — anomaly flag added (e.g. young_endorser_cluster, repetitive_endorsements).
• flag_removed — flag cleared.
• did_revoked — emitted by manual revocation tooling.

Verifying the signature

The registry_signature field is computed as Ed25519(JCS({did, trust_score, computed_at, valid_until, policy_version})) using the registry private key. Verifiers reconstruct the canonical payload and verify against the public JWK.

Python

import base64
import jcs
import requests
from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey

# Fetch registry public key
jwk = requests.get("https://api.moltrust.ch/.well-known/registry-key.json").json()
pub_bytes = base64.urlsafe_b64decode(jwk["x"] + "=" * (-len(jwk["x"]) % 4))
pub = Ed25519PublicKey.from_public_bytes(pub_bytes)

# Fetch signed trust score
score = requests.get(
    "https://api.moltrust.ch/skill/trust-score/did:moltrust:abc123"
).json()

signing_payload = {
    "did":            score["did"],
    "trust_score":    score["trust_score"],
    "computed_at":    score["computed_at"],
    "valid_until":    score["valid_until"],
    "policy_version": score["evaluation_context"]["policy_version"],
}
canonical = jcs.canonicalize(signing_payload)
sig = base64.urlsafe_b64decode(
    score["registry_signature"] + "=" * (-len(score["registry_signature"]) % 4)
)

# Verify — raises InvalidSignature on tamper
pub.verify(sig, canonical)
print("Signature verified.")

TypeScript

import { canonicalize } from "@truestamp/canonify"   // or any RFC 8785 lib
import { ed25519 } from "@noble/curves/ed25519"

function b64urlDecode(s: string): Uint8Array {
  const pad = "=".repeat((4 - s.length % 4) % 4)
  return Uint8Array.from(atob((s + pad).replace(/-/g, "+").replace(/_/g, "/")), c => c.charCodeAt(0))
}

const jwk = await fetch("https://api.moltrust.ch/.well-known/registry-key.json")
  .then(r => r.json())
const pubKey = b64urlDecode(jwk.x)

const score = await fetch("https://api.moltrust.ch/skill/trust-score/did:moltrust:abc123")
  .then(r => r.json())

const signingPayload = {
  did:            score.did,
  trust_score:    score.trust_score,
  computed_at:    score.computed_at,
  valid_until:    score.valid_until,
  policy_version: score.evaluation_context.policy_version,
}
const canonical = new TextEncoder().encode(canonicalize(signingPayload))
const sig = b64urlDecode(score.registry_signature)

const valid = ed25519.verify(sig, canonical, pubKey)
if (!valid) throw new Error("Invalid registry signature")
console.log("Signature verified.")

Operational notes

• Free during Early Access. After EA, /caep/pending moves to x402 at $0.05/call (consistent with /agent/score). Acknowledge and well-known stay free.
• Rate-limit: 120 requests/hour per DID on the pending endpoint.
• Event TTL: 24h default. Long enough that a polling client catches up after a brief outage.
• Retention: acknowledged events are hard-deleted after 90 days.
• Score-change threshold: ≥10 points (absolute delta).

Key rotation

The current key is moltrust-registry-2026-v1 (Ed25519, kid in the JWK). Rotation is annual (next: January 2027). Old kids remain valid for verifying historical receipts for 90 days after rotation. The well-known endpoint will eventually publish JWKS (multiple keys) once a rotation actually happens.

XMTP roadmap

An XMTP push channel is planned for Q2/Q3 2026. It will mirror the same event types over the XMTP wallet of the registry, letting clients receive events without polling. Polling stays the stable v1 channel; XMTP will be additive.