The tiny capabilities of smart objects in terms of computational
power, memory and energy create difficulties in
applying well-established security protocols. Smart objects
and sensors are vulnerable to attacks because of the lack of
security support in the primary design of low lossy
networks. The most critical factor for secure communication
between smart objects is the required energy. Mechanisms
for mitigating security threats result in consuming more
energy form their already limited energy resources. Nevertheless,
if no security encryption exists, a malicious node
can easily intercept transmitted information or impersonate
a receiver. Furthermore, privacy seems to be challenging
because of the smart objects’ weakness to anticipate and
sense possible listeners. However, the use of AES-128
(Advanced Encryption Standard) link-layer security mechanism
of IEEE 802.15.4 seems to have lightweight properties
but the necessary time to encrypt and decrypt interchanging
messages increases significantly the energy consumption.
The encryption algorithm used in 802.15.4 is AES with a 128 b
key length (16 Bytes). Moreover AES algorithm is not only
used to encrypt the information but to validate the sent data.
This concept is called Data Integrity and it is achieved using
an MIC (or an MAC) which is appended to the message. This
code ensures the integrity of the MAC header and the
attached payload data. On the other hand, jamming attacks
can be detected using suitable algorithms based on dropped
packets or the decrease of the signal to noise ratio
(Fragkiadakis et al., June 2010). In order to mitigate such
attacks, two possible solutions may be applied: (i) an
increase in the power level or (ii) a channel assignment
procedure as described in (Petroulakis et al., June 2009). The
use of both mitigating factors severely affects the energy
consumed in smart objects, as will be described extensively
in the next sections.