Webhook Events

public static bool IsValidWebhookEventSignature(  
        string requestBody,  
        string signatureHeader,  
        string signatureKey,  
        string url)  
{  
  //url is where the webhook is being sent to and includes https example: "https://webhook.site/462a579b-1cb2-4ae4-b4de-631fad16b3dd"
	if (string.IsNullOrEmpty(signatureKey))  
		throw new ArgumentNullException(nameof (signatureKey));  
	if (string.IsNullOrEmpty(url))  
		throw new ArgumentNullException(nameof (url));  
	byte[] bytes = Encoding.UTF8.GetBytes(url + "$" + requestBody); //Concat strings with a $  
	using var hmacshA256 = new HMACSHA256(Encoding.UTF8.GetBytes(signatureKey));  
	return Convert.ToBase64String(hmacshA256.ComputeHash(bytes)).Equals(signatureHeader);  
}

function IsValidWebhookEventSignature(string $requestBody, string $signatureHeader, string $signatureKey, string $url): bool
{
  // Check for empty arguments
  if (empty($signatureKey)) {
    throw new ArgumentNullException('signatureKey');
  }
  if (empty($url)) {
    throw new ArgumentNullException('url');
  }

  // Concatenate url and request body with a delimiter
  $data = $url . '$' . $requestBody;

  // Create HMAC object with SHA256 algorithm
  $hmac = hash_hmac('sha256', $data, $signatureKey, true);

  // Encode the HMAC hash to base64 and compare with signature
  return base64_encode($hmac) === $signatureHeader;
}