Methods and computing devices configured to implement the methods for authenticating processing devices on a system on chip (SoC) for encrypted communication. An SoC may include a plurality of memories configured to store equivalent ephemeral shared data sets. A first processing device of the SoC may select first elements from a first ephemeral shared data set, generate a rule set indicating the first elements, send the rule set to a second processing device of the SoC, and generate a first result based on the first elements. The second processing device may receive the rule set, select second elements from a second ephemeral shared data set, generate a second result based on the second elements, and send the second result to the first processing device. The first processing device may receive the second result and authenticate the second processing device based on a comparison of the first and second results.