Implementing the Transport Layer Security Protocol for Embedded Systems

Abstract: Web servers are increasingly being used in embedded devices as a communication medium. As more systems connect to the Internet, the need for security is increasing. The Transport Layer Protocol (TLS) is the successor of Secure Socket Layer (SSL) and provides security in almost all secure Internet transactions. This thesis aims to investigate if TLS can be adapted to embedded systems without sacrificing much of the system resources available. A literature study and an implementation of TLS have been performed. The literature study determined resource intense parts of TLS, hardware support as well as export laws applicable to TLS. The different parts of the implementation are evaluated on an ARM7-core to determine the execution times. The results for the symmetric ciphers AES and 3DES are compared when measuring execution times using both software and hardware solutions. The size of the implementation is also measured. TLS was shown to be able to integrate on embedded systems. Practical issues such as certificates and keys can be solved in different ways to suite the target environment. The largest remaining issue is the execution time for asymmetric algorithms. The results that are provided clearly illustrates that the RSA used for key exchange is very time consuming. Alternative solutions to gain better performance are discussed.