CoAP + DTLS: A Comprehensive Overview of Cryptographic Performance on an IOT Scenario

Internet of things (IoT) and Fog computing applications deal with sensitive data and need security tools to be protected against attackers. CoAP (Constrained Application Protocol), combined with DTLS (Datagram Transport Layer Security), provides security to IoT/Fog applications. However, processing times need to be considered when using this combination due to IoT/Fog environment constraints. Our work presents a CoAP with DTLS application and analyzes the performance of Raspberry Pi 3 during DTLS handshakes, data encryption and data decryption with the most relevant cipher suites. The performance of confirmable and non-confirmable CoAP POST requests is also measured and discussed in our work. We discovered that cipher suites that use RSA as an authentication method on handshake are slightly faster than cipher suites that use ECDSA, while symmetric key encryption with AES256(128)GCM are 40% faster than AES256(128) default modes. Our study also suggests CoAP modifications to obtain higher efficiency, and it might help future IoT/Fog application developers to understand CoAP and DTLS union, providing an application example and performance metrics.