Secure authentication while communicating data between sender and receiver nodes is a key concept when providing Internet of Things as a service. Hash algorithms can provide such an authentication mechanism for IoT based applications. The most recent secure hash algorithm technique standardized by the NIST is SHA-3. SHA-3 is fully apt in ensuring authentication for a sender and receiver transaction. A novel signature generating technique based on SHA-3 is presented in the paper. Two of the popular IoT communication models of publish subscribe and request response are examined under this authentication scheme. The sender generates a unique hash code for the data that it is about to send. This hash code serves as the authenticating token for the transaction. Mechanisms for the sender receiver interaction are built into the program codes in both the simulated communication models. The system architecture also manages interaction of the receiver with the cloud. This interaction ensures proper authentication through the mechanisms and api(s) provided by the cloud service providers, and these mechanisms are also integrated into the simulation. Both the cloud services used in the system architecture, i.e. cloud messaging as a service, and cloud database as a service ensure that the sender's identity is verified. In this way a blanket authentication system is set up for the aforementioned IoT architectures. © 2019 Procedia Computer Science. All rights reserved.