The Performance of TLS Protocol in Vehicular Embedded Computers

Abstract: Transport Layer Security (TLS) is a protocol that is widely used to secure Hypertext Transfer Protocol (HTTP) data transported across the Internet. This protocol comes with a set of operations that are for encryption, decryption, sharing keys for encryption etc. Studies have shown that these operations often cause performance degradation. So to implement TLS protocol in an environment with performance limitations (in terms of response time and usability), it becomes necessary to have an idea of performance implication of TLS protocol in that specific environment.

This thesis work has contributed to understanding the performance of TLS in the specific setting of vehicles’ embedded computers. Different performance tests were done to understand performance differences between implementations using the TLS protocol and those not using it. Furthermore, this thesis gave an idea about how different TLS parts in the HTTP communication stack perform. Lastly, tests were conducted to understand how different encryption schemes and algorithms supported by TLS protocol perform in this specific setting.

Results of this work demonstrated that TLS protocol induces some delays in response time that remarkably could affect usability of the system. This delay is due to TLS operations that are necessary for agreeing on sets of keys, algorithms, ciphers and protocols to be used when communicating with TLS protocol. Delay in these operations is caused by a number of factors; some found by this thesis work are size of encryption keys, type of cipher and algorithm used and size of the payload to be operated on. Based on these results, there are some recommendations in this work that when followed would help to optimally utilize the power of TLS protocol. Besides these findings, an open-source software program that performs all of the performance tests explained in this thesis work was produced. This program will potentially allow others to reproduce this research in their specific environments.