The Amazon SNS Message Validator for PHP library allows you to validate that incoming HTTP(S) POST messages are valid Amazon SNS notifications. This library is standalone and does not depend on the AWS SDK for PHP or Guzzle; however, it does require PHP 5.4+ and that the OpenSSL PHP extension is installed. Next, you must create an instance of MessageValidator, and then use either the isValid() or validate(), methods to validate the message. The message validator checks the SigningCertURL...