KYC API連携ガイド：APIの全フローをエンドツーエンドで解説

# Required
DIDIT_API_KEY=your_api_key_here
DIDIT_WEBHOOK_SECRET=your_webhook_secret_here

# Your workflow ID (from the Console)
DIDIT_WORKFLOW_ID=your_workflow_id_here

curl -X POST https://verification.didit.me/v3/session/ \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{
    "workflow_id": "your-workflow-id",
    "callback": "https://yourapp.com/verification-complete",
    "vendor_data": "user-123"
  }'

curl -X POST https://verification.didit.me/v3/session/ \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{
    "workflow_id": "11111111-2222-3333-4444-555555555555",
    "callback": "https://yourapp.com/verification-complete",
    "vendor_data": "user-123",
    "metadata": {
      "plan": "premium",
      "signup_source": "mobile-app"
    },
    "contact_details": {
      "email": "alex.sample@example.com",
      "email_lang": "en",
      "send_notification_emails": true,
      "phone": "+15550101000"
    },
    "expected_details": {
      "first_name": "John",
      "last_name": "Doe",
      "date_of_birth": "1990-01-01",
      "expected_document_types": ["P", "ID"]
    }
  }'

{
  "session_id": "11111111-2222-3333-4444-555555555555",
  "session_number": 43762,
  "session_token": "3FaJ9wLqX2Mz",
  "url": "https://verify.didit.me/session/3FaJ9wLqX2Mz",
  "vendor_data": "user-123",
  "metadata": {
    "plan": "premium",
    "signup_source": "mobile-app"
  },
  "status": "Not Started",
  "workflow_id": "11111111-2222-3333-4444-555555555555",
  "workflow_version": 3,
  "callback": "https://yourapp.com/verification-complete"
}

<iframe
  src="{url}"
  style="width: 100%; height: 700px; border: none;"
  allow="camera; microphone; geolocation; clipboard-write; fullscreen; autoplay; encrypted-media; digital-credentials-get"
></iframe>

window.location.href = session.url;

// React Native
<WebView source={{ uri: session.url }} />

{
  "event_id": "9c0c8b8a-1111-4222-9333-444444444444",
  "webhook_type": "status.updated",
  "timestamp": 1774970000,
  "created_at": 1774969994,
  "application_id": "11111111-2222-3333-4444-555555555555",
  "environment": "live",
  "session_id": "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee",
  "status": "Approved",
  "workflow_id": "22222222-3333-4444-5555-666666666666",
  "workflow_version": 4,
  "vendor_data": "user-123",
  "metadata": { "plan": "premium" },
  "decision": {
    "session_id": "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee",
    "status": "Approved",
    "id_verifications": [
      { "node_id": "id_verification_1", "status": "Approved", "document_type": "Passport", "warnings": [] }
    ],
    "liveness_checks": [
      { "node_id": "liveness_1", "status": "Approved", "method": "PASSIVE", "score": 95.4, "warnings": [] }
    ],
    "face_matches": [
      { "node_id": "face_match_1", "status": "Approved", "score": 96.1, "warnings": [] }
    ],
    "reviews": []
  }
}

const crypto = require("crypto");

// Match Didit's float normalisation: whole-valued floats serialise as ints.
function shortenFloats(data) {
  if (Array.isArray(data)) return data.map(shortenFloats);
  if (data !== null && typeof data === "object") {
    return Object.fromEntries(
      Object.entries(data).map(([key, value]) => [key, shortenFloats(value)])
    );
  }
  return data;
}

// Sort object keys recursively before re-stringifying.
function sortKeys(obj) {
  if (Array.isArray(obj)) return obj.map(sortKeys);
  if (obj !== null && typeof obj === "object") {
    return Object.keys(obj).sort().reduce((acc, key) => {
      acc[key] = sortKeys(obj[key]);
      return acc;
    }, {});
  }
  return obj;
}

function verifyWebhook(rawBody, signatureV2, timestamp, secret) {
  // 1. Reject anything older than 5 minutes
  const now = Math.floor(Date.now() / 1000);
  if (Math.abs(now - parseInt(timestamp, 10)) > 300) return false;

  // 2. Recompute HMAC-SHA256 against the canonical JSON Didit signs
  const canonical = JSON.stringify(sortKeys(shortenFloats(JSON.parse(rawBody))));
  const expected = crypto.createHmac("sha256", secret).update(canonical, "utf8").digest("hex");

  // 3. Constant-time compare
  const a = Buffer.from(expected, "utf8");
  const b = Buffer.from(signatureV2, "utf8");
  return a.length === b.length && crypto.timingSafeEqual(a, b);
}

curl https://verification.didit.me/v3/session/{session_id}/decision/ \
  -H "x-api-key: YOUR_API_KEY"

const express = require("express");
const crypto = require("crypto");
const app = express();

// Create verification session
app.post("/api/verify", async (req, res) => {
  const { userId } = req.body;

  const response = await fetch("https://verification.didit.me/v3/session/", {
    method: "POST",
    headers: {
      "x-api-key": process.env.DIDIT_API_KEY,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      workflow_id: process.env.DIDIT_WORKFLOW_ID,
      callback: `${process.env.APP_URL}/verification-complete`,
      vendor_data: userId,
    }),
  });

  const session = await response.json();

  // Store session_id associated with user
  await db.users.update({
    where: { id: userId },
    data: { verificationSessionId: session.session_id },
  });

  res.json({
    verificationUrl: session.url,             // hosted verification URL
    sessionToken: session.session_token,      // for native/web SDKs
  });
});

// Handle webhook — uses verifyWebhook / shortenFloats / sortKeys from Step 5
app.post(
  "/api/webhook",
  express.raw({ type: "application/json" }),
  (req, res) => {
    const signature = req.get("X-Signature-V2");
    const timestamp = req.get("X-Timestamp");

    if (
      !verifyWebhook(
        req.body.toString("utf8"),
        signature,
        timestamp,
        process.env.DIDIT_WEBHOOK_SECRET,
      )
    ) {
      return res.status(401).json({ error: "Invalid signature" });
    }

    const payload = JSON.parse(req.body);
    const { event_id, session_id, status, vendor_data } = payload;

    // Idempotency: the same event_id is reused on retries and fan-out.
    // Skip events you have already processed (e.g. a processed_events table).

    // Update user's verification status (status values are case-sensitive strings)
    if (status === "Approved") {
      db.users.update({
        where: { id: vendor_data },
        data: { isVerified: true, verifiedAt: new Date() },
      });
    }

    // Return 2xx quickly (Didit's delivery timeout is 5s); do heavy work asynchronously
    res.json({ received: true });
  },
);

app.listen(3000);

from fastapi import FastAPI, Request, HTTPException
import httpx
import hashlib
import hmac
import json
import os
import time

app = FastAPI()

@app.post("/api/verify")
async def create_verification(user_id: str):
    async with httpx.AsyncClient() as client:
        response = await client.post(
            "https://verification.didit.me/v3/session/",
            headers={
                "x-api-key": os.environ["DIDIT_API_KEY"],
                "Content-Type": "application/json"
            },
            json={
                "workflow_id": os.environ["DIDIT_WORKFLOW_ID"],
                "callback": f"{os.environ['APP_URL']}/verification-complete",
                "vendor_data": user_id
            }
        )

    session = response.json()
    return {
        "verification_url": session["url"],            # hosted verification URL
        "session_token": session["session_token"],     # for native/web SDKs
    }

def shorten_floats(data):
    """Match Didit: whole-valued floats serialise as ints."""
    if isinstance(data, dict):
        return {k: shorten_floats(v) for k, v in data.items()}
    if isinstance(data, list):
        return [shorten_floats(x) for x in data]
    if isinstance(data, float) and data.is_integer():
        return int(data)
    return data

@app.post("/api/webhook")
async def handle_webhook(request: Request):
    payload = await request.json()
    signature = request.headers.get("X-Signature-V2")
    timestamp = request.headers.get("X-Timestamp")

    # Verify timestamp freshness
    if not signature or not timestamp or abs(int(time.time()) - int(timestamp)) > 300:
        raise HTTPException(status_code=401, detail="Request too old")

    # Recompute Didit's V2 canonical JSON: shortened floats, sorted keys,
    # compact separators, Unicode preserved (ensure_ascii=False)
    canonical = json.dumps(
        shorten_floats(payload),
        sort_keys=True,
        separators=(",", ":"),
        ensure_ascii=False,
    )
    expected = hmac.new(
        os.environ["DIDIT_WEBHOOK_SECRET"].encode("utf-8"),
        canonical.encode("utf-8"),
        hashlib.sha256
    ).hexdigest()

    if not hmac.compare_digest(signature, expected):
        raise HTTPException(status_code=401, detail="Invalid signature")

    # Idempotency: dedupe on payload["event_id"] (reused on retries)

    if payload["status"] == "Approved":
        # Update user in database
        pass

    return {"received": True}