Performance evaluation of the TLS handshake in the context of embedded devices

Abstract

With the strong advent of mobile and embedded devices communicating in a wireless way using the air inter-face, the need for secure connections, efficient en- and decryption and strong authentication becomes more and more pronounced. The Transport Layer Security (TLS) protocol provides a convenient and well researched way to establish a secure authenticated connection between 2 communicating parties. By utilizing Elliptic Curve Cryptography (ECC) instead of the more common RSA algorithms, asymmetric cryptography is feasible even for tiny integrated devices. However, when dealing with heavily resource constrained appliances, it does not suffice to speed up just the cryptography related computations, but to also keep the communication necessary to establish a secure connection to a minimum, in order not to drain the scarce energy resources of the small devices. In this work we give a thorough investigation of the communication overhead the TLS handshake requires when used in conjunction with elliptic curve cryptography, together with experimental results using our own library handcrafted to support ECC on embedded systems. The results give implementers a useful guide for weighing security versus performance and also justifies the need for new authentication methods, requiring less communication overhead.