# Didit Webhooks

## When to Use This Skill

* How do I receive Didit webhooks?
* How do I verify the Didit `X-Signature` header?
* Why is my Didit webhook signature verification failing?
* How do I handle `status.updated` (session Approved / Declined / In Review) events?
* How do I handle `data.updated` events after a manual review?

## Verification (core)

Didit signs every webhook with HMAC-SHA256, keyed with the destination's `secret_shared_key` (used as a raw string). `X-Signature` is the **hex** digest of the **exact raw request body**. `X-Timestamp` (unix seconds) is sent separately and is **not** part of the signed input. Didit recommends rejecting requests where `abs(now - X-Timestamp) > 300`, but Hookdeck retries and replays keep the original header, so the examples make that check opt-in (`DIDIT_TIMESTAMP_TOLERANCE_SECONDS`, default `0`).

Node:

```javascript
const crypto = require('crypto');

// toleranceSec = 0 (default) skips the X-Timestamp check; a positive value opts in
function verify(rawBody, signature, timestamp, secret, toleranceSec = 0, now = Math.floor(Date.now() / 1000)) {
  if (!signature) return false;
  if (toleranceSec > 0 && !(Math.abs(now - Number(timestamp)) <= toleranceSec)) return false;
  const expected = crypto.createHmac('sha256', secret).update(rawBody).digest('hex');
  const a = Buffer.from(signature), b = Buffer.from(expected);
  return a.length === b.length && crypto.timingSafeEqual(a, b);
}

```

Python:

```python
import hmac, hashlib, time

def verify(raw_body: bytes, signature: str, timestamp: str, secret: str, tolerance: int = 0) -> bool:
    # tolerance = 0 (default) skips the X-Timestamp check; a positive value opts in
    if not signature:
        return False
    if tolerance > 0 and (not timestamp or not timestamp.isdigit() or abs(time.time() - int(timestamp)) > tolerance):
        return False
    expected = hmac.new(secret.encode(), raw_body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(signature, expected)

```

> **For complete handlers with route wiring, event dispatch, and tests**, see:
> 
> * [examples/express/](https://github.com/hookdeck/webhook-skills/tree/main/skills/didit-webhooks/examples/express/)
> * [examples/nextjs/](https://github.com/hookdeck/webhook-skills/tree/main/skills/didit-webhooks/examples/nextjs/)
> * [examples/fastapi/](https://github.com/hookdeck/webhook-skills/tree/main/skills/didit-webhooks/examples/fastapi/)

Didit has no webhook verification SDK, so verification is manual. `X-Signature-V2` (HMAC of re-serialized, sorted-key JSON) is an alternative for stacks that re-encode the body before your handler runs, and the deprecated `X-Signature-Simple` only authenticates the envelope, not `decision`. See [references/verification.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/didit-webhooks/references/verification.md).

## Common Event Types

| Event (`webhook_type`) | Description |
| --- | --- |
| `status.updated` | A KYC or KYB session's status changed (Approved, Declined, In Review, Abandoned, Resubmitted, ...) |
| `data.updated` | Verification data was edited after creation, e.g. by a manual reviewer |

Didit also delivers entity, transaction, Travel Rule and Investigator events (for example `user.status.updated`, `transaction.created`). There is no wildcard: list each event on the destination. See [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/didit-webhooks/references/overview.md).

> **For the full event reference**, see [Didit's webhook documentation](https://docs.didit.me/integration/webhooks).

## Important Headers

| Header | Description |
| --- | --- |
| `X-Signature` | Hex HMAC-SHA256 of the exact raw body |
| `X-Timestamp` | Unix seconds when Didit dispatched the webhook (refreshed on each retry) |
| `X-Signature-V2` | Hex HMAC-SHA256 of sorted-key, Unicode-preserved compact JSON (alternative) |
| `X-Signature-Simple` | Deprecated; envelope-only signature |

## Environment Variables

```bash
DIDIT_WEBHOOK_SECRET=your_secret_shared_key   # Returned once when the destination is created
DIDIT_TIMESTAMP_TOLERANCE_SECONDS=0           # Optional; a positive value turns on the timestamp check

```

## Local Development

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

```

## Reference Materials

* [references/overview.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/didit-webhooks/references/overview.md) - Didit webhook concepts, events, payload shape
* [references/setup.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/didit-webhooks/references/setup.md) - Creating a destination and getting the secret
* [references/verification.md](https://github.com/hookdeck/webhook-skills/blob/main/skills/didit-webhooks/references/verification.md) - Signature verification details and gotchas