Ethoca Webhooks Skill

Ethoca (a Mastercard company) delivers Alerts — early fraud and dispute notifications from issuers — to merchants. The Alerts Push API HTTPS-POSTs JSON to an endpoint you register with the Ethoca Customer Delivery Team.

When to Use This Skill

• How do I receive Ethoca Alerts webhooks (Push API)?
• How do I secure an Ethoca webhook endpoint without a signature header?
• How do I handle Ethoca fraud and dispute alerts?
• Why is there no X-Ethoca-Signature / HMAC header to verify?
• How does Ethoca mTLS (MSSL) delivery work?

Verification (core)

There is NO per-message HMAC/signature header on Ethoca Push API alerts. Do not look for X-Ethoca-Signature or a Standard Webhooks header — none exists. Trust is established primarily by the transport:

1. Transport — mutual TLS (MSSL) — the definitive check. Ethoca presents a client certificate; your server must trust the Entrust CA and require a client cert. This is enforced at your TLS terminator / load balancer, not in app code, and is the actual mechanism that authenticates the delivery.
2. Application — HTTP Basic Auth (OPTIONAL). If you agree Basic Auth credentials with the Ethoca Customer Delivery Team at onboarding, Ethoca sends Authorization: Basic base64(username:password) and your handler checks it. Whether Ethoca sends Basic Auth is not guaranteed by the API — an endpoint secured by mTLS alone may receive no Authorization header.

An IP allowlist of Ethoca's egress ranges is a recommended additional layer.

Enforce Basic Auth only when credentials are configured — if none are set, accept the delivery and rely on mTLS rather than returning 401. When configured, verify the credentials with a timing-safe comparison. Node:

const crypto = require('crypto');

function safeEqual(a, b) {
  const ab = Buffer.from(a), bb = Buffer.from(b);
  return ab.length === bb.length && crypto.timingSafeEqual(ab, bb);
}

function verifyEthocaAuth(authHeader, username, password) {
  if (!authHeader || !authHeader.startsWith('Basic ')) return false;
  const decoded = Buffer.from(authHeader.slice(6), 'base64').toString('utf-8');
  const i = decoded.indexOf(':');
  if (i === -1) return false;
  return safeEqual(decoded.slice(0, i), username) &&
         safeEqual(decoded.slice(i + 1), password);
}

No body signature means the raw request body is not security-critical here, so ordinary JSON parsing is fine (unlike HMAC-based providers). Authenticity comes from mTLS + Basic Auth on the connection, not from the payload bytes.

Outbound outcomes are different. When you report an alert outcome back to Ethoca via the Outcome API, that call uses OAuth 1.0a with a PKCS#12 (.p12) keystore and the mastercard-oauth1-signer helper — see references/verification.md. The sibling product Ethoca Consumer Clarity uses a different ETHOCA-SHA1 HMAC scheme; do not apply it here.

For complete handlers with route wiring, event dispatch, and tests, see:

• examples/express/
• examples/nextjs/
• examples/fastapi/

Alert Categories

Ethoca alerts fall into two categories, carried in the alertType field:

Verify literal values at onboarding. The exact alertType enum is not published publicly and has historically been numeric. Confirm the values in your Ethoca onboarding schema and normalize to the two categories above — see references/overview.md.

Environment Variables

Optional — set both only if you agreed Basic Auth credentials at onboarding. Leave them unset for an mTLS-only endpoint (the handler then skips the Basic Auth check instead of returning 401).

ETHOCA_WEBHOOK_USERNAME=your_basic_auth_username   # Optional; agreed with Ethoca onboarding
ETHOCA_WEBHOOK_PASSWORD=your_basic_auth_password   # Optional; agreed with Ethoca onboarding

Local Development

# Start tunnel (no account needed)
npx hookdeck-cli listen 3000 ethoca --path /webhooks/ethoca

Reference Materials

• references/overview.md - Ethoca Alerts concepts, payload, alertType
• references/setup.md - Endpoint registration with the Customer Delivery Team
• references/verification.md - mTLS, Basic Auth, and the OAuth 1.0a Outcome API