Guía del desarrollador de Bank Transfer

const crypto = require('crypto');
const express = require('express');

const TOLERANCE_SECONDS = 300; // 5 minutos

function validateWebhook(rawBody, timestamp, signature, secret) {
  if (!timestamp || !signature) return false;

  const ageSeconds = Math.abs(Math.floor(Date.now() / 1000) - parseInt(timestamp, 10));
  if (Number.isNaN(ageSeconds) || ageSeconds > TOLERANCE_SECONDS) return false;

  const signedPayload = Buffer.concat([
    Buffer.from(timestamp, 'utf8'),
    Buffer.from('.', 'utf8'),
    rawBody,
  ]);

  const expected = 'sha256=' + crypto
    .createHmac('sha256', secret)
    .update(signedPayload)
    .digest('hex');

  const expectedBuf = Buffer.from(expected);
  const receivedBuf = Buffer.from(signature);
  if (expectedBuf.length !== receivedBuf.length) return false;

  return crypto.timingSafeEqual(expectedBuf, receivedBuf);
}

// Use raw body — not req.body (parsed JSON)
app.post('/webhooks/ted',
  express.raw({ type: 'application/json' }),
  (req, res) => {
    const timestamp = req.headers['x-webhook-timestamp'];
    const signature = req.headers['x-webhook-signature'];

    if (!validateWebhook(req.body, timestamp, signature, process.env.WEBHOOK_SIGNING_SECRET)) {
      return res.status(401).send('Invalid signature');
    }

    const payload = JSON.parse(req.body.toString());
    // process payload...
    res.status(200).send('OK');
  }
);

import hmac
import hashlib
import time

TOLERANCE_SECONDS = 300  # 5 minutos

def validate_webhook(raw_body: bytes, timestamp: str, signature: str, secret: str) -> bool:
    if not timestamp or not signature:
        return False

    try:
        age = abs(int(time.time()) - int(timestamp))
    except ValueError:
        return False
    if age > TOLERANCE_SECONDS:
        return False

    signed_payload = timestamp.encode() + b"." + raw_body
    expected = "sha256=" + hmac.new(
        secret.encode(),
        signed_payload,
        hashlib.sha256,
    ).hexdigest()

    return hmac.compare_digest(expected, signature)

import (
    "crypto/hmac"
    "crypto/sha256"
    "encoding/hex"
    "strconv"
    "time"
)

const toleranceSeconds = 300 // 5 minutos

func validateWebhook(rawBody []byte, timestamp, signature, secret string) bool {
    if timestamp == "" || signature == "" {
        return false
    }

    ts, err := strconv.ParseInt(timestamp, 10, 64)
    if err != nil {
        return false
    }
    if diff := time.Now().Unix() - ts; diff < -toleranceSeconds || diff > toleranceSeconds {
        return false
    }

    mac := hmac.New(sha256.New, []byte(secret))
    mac.Write([]byte(timestamp))
    mac.Write([]byte("."))
    mac.Write(rawBody)
    expected := "sha256=" + hex.EncodeToString(mac.Sum(nil))

    return hmac.Equal([]byte(expected), []byte(signature))
}