AWS IoT Core enables secure communication between devices by using TLS/SSL and X.509 certificates. TLS/SSL is used to encrypt data in transit and X.509 certificates are used to authenticate devices.
For example, when a device wants to connect to AWS IoT Core, it must present a valid X.509 certificate that has been issued by AWS IoT Core. AWS IoT Core will then validate the certificate and if it is valid, the device will be allowed to connect. Once the connection is established, the data is encrypted using TLS/SSL.