7. Conclusion
We have introduced a standard based security architecture
with two-way authentication for the IoT. The authentication
is performed during a fully authenticated DTLS
handshake and based on an exchange of X.509 certificates
containing RSA keys. The extensive evaluation, based on
real IoT systems, shows that our proposed architecture
provides message integrity, confidentiality and authenticity
with affordable energy, end-to-end latency and memory
overhead. This shows that DTLS is a feasible security
solution for the emerging IoT. We consider a fully authenticated
handshake with strong security through 2048-bit
RSA keys feasible for sensor nodes equipped with a TPM
chip, since a fully authenticated, RSA based handshake
consumes as little as 488 mJ. The memory requirement of
under 20 kB RAM are well below the 48 kB of memory offered
by our sensor node. Sensor nodes without a TPM chip
forego protection against physical tampering, but can still
perform a DTLS handshake based on ECC which could be
performed on our platform with little more than 100 mJ
of energy usage. Previous work has demonstrated techniques
to minimize packet headers for similar protocols
[14]. We plan to apply these techniques to DTLS in future
work together with an Authenticated Encryption with
Associated Data (AEAD) mode of operation to achieve the
reduction in network overhead we have outlined in Section
5.4. Another focus will be the inclusion of more constrained
nodes without a TPM in our architecture, for
which we plan to use a variant of the DTLS pre-shared
key cipher suites.