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import crypto from "crypto"
 
const TOLERANCE_SECONDS = 300
 
export function verifyKukoPay(rawBody, signatureHeader, secret) {
  // 頭裏可能有多個 v1=，逐個收集
  const parts = signatureHeader.split(",").map((item) => {
    const index = item.indexOf("=")
    return [item.slice(0, index).trim(), item.slice(index + 1).trim()]
  })
 
  const timestamp = parts.find(([key]) => key === "t")?.[1]
  const received = parts.filter(([key]) => key === "v1").map(([, value]) => value)
  if (!timestamp || received.length === 0) return false
 
  // 拒絕過舊的時間戳，避免簽名被重放
  if (Math.abs(Date.now() / 1000 - Number(timestamp)) > TOLERANCE_SECONDS) {
    return false
  }
 
  const expected = Buffer.from(
    crypto
      .createHmac("sha256", secret)
      .update(`${timestamp}.${rawBody}`)
      .digest("hex")
  )
 
  // 任意一個匹配即可：輪換窗口內新舊密鑰會各簽一次
  return received.some((candidate) => {
    const buffer = Buffer.from(candidate)
    return (
      buffer.length === expected.length &&
      crypto.timingSafeEqual(buffer, expected)
    )
  })
}

import hashlib
import hmac
import time
 
TOLERANCE_SECONDS = 300
 
 
def verify_kukopay(raw_body: bytes, signature_header: str, secret: str) -> bool:
    timestamp = None
    received = []
 
    for item in signature_header.split(","):
        key, _, value = item.strip().partition("=")
        if key == "t":
            timestamp = value
        elif key == "v1":
            received.append(value)
 
    if not timestamp or not received:
        return False
 
    if abs(time.time() - int(timestamp)) > TOLERANCE_SECONDS:
        return False
 
    expected = hmac.new(
        secret.encode(),
        f"{timestamp}.".encode() + raw_body,
        hashlib.sha256,
    ).hexdigest()
 
    # 輪換窗口內新舊密鑰各簽一次，任意一個匹配即合法
    return any(hmac.compare_digest(expected, candidate) for candidate in received)

<?php
 
function verify_kukopay(string $rawBody, string $signatureHeader, string $secret): bool
{
    $timestamp = null;
    $received = [];
 
    foreach (explode(',', $signatureHeader) as $item) {
        [$key, $value] = array_pad(explode('=', trim($item), 2), 2, null);
        if ($key === 't') {
            $timestamp = $value;
        } elseif ($key === 'v1') {
            $received[] = $value;
        }
    }
 
    if ($timestamp === null || $received === []) {
        return false;
    }
 
    if (abs(time() - (int) $timestamp) > 300) {
        return false;
    }
 
    $expected = hash_hmac('sha256', $timestamp . '.' . $rawBody, $secret);
 
    // 輪換窗口內新舊密鑰各簽一次，任意一個匹配即合法
    foreach ($received as $candidate) {
        if (hash_equals($expected, $candidate)) {
            return true;
        }
    }
 
    return false;
}