**2.1. Sensor devices**

2 Will-be-set-by-IN-TECH

Multivariate Quadratic Almost Group (MQQ) was proposed in academia. Experiments performed in the FPGA and PC platforms showed that MQQ is faster than algorithms such as RSA and ECC [1, 2]. Algorithms involved in this study are asymmetric, but each one works

Many studies have evaluated performance of cryptographic algorithms in WSNs, but there is no standardization in the performance analysis. As stated by Margi [3] studies on performance evaluation of cryptographic algorithms for WSNs are often quite different in terms of methodology, platform, metrics and focus of analysis, what difficult a direct comparison among the obtained results. Thus, this chapter describes a theoretical study of cryptographic such as RSA, ECC, HECC and MQQ as well as the performance analysis of

Sensor nodes are electronic devices that have as main components units of storage, processing, sensing and transmission. Usually, these devices have low computational power, nevertheless play an important role in ubiquitous computing, because they have function of collecting data in a given environment, passing them through a wireless network. According to [4] WSNs can be seen as a special type of MANET (Mobile Ad hoc NETwork) that tend to run a collaborative basis where the elements (sensor nodes) provide data that are processed (or consumed) by

The operation area of a WSN is very large and can be used in environmental monitoring, control temperature and humidity, vehicle traffic control, monitoring of human body organs, among others. Figure 1 illustrates a scenario of WSNs in the medical area where patients that are being monitored can be in a hospital, at home, or anywhere else performing an activity

Some application areas of WSNs require security in the information transport, such as the scenario illustrated by figure 1, where sensor nodes implanted in the human body reporting

routine. Sensing data are sent to health professionals through the Internet.

with a specific encryption mode.

these algorithms in WSN.

**2. Wireless sensor network**

special nodes called sink nodes.

**Figure 1.** Scenario of Wireless Sensor Network [5]

Sensor devices are basically formed by a computational part responsible for storing and transmitting data, and a sensing portion which can be formed by one or more sensors, such as acoustic, seismic, infrared video camera, heat temperature and pressure [4]. In general two modulation formats are available: Frequency-Shift-Keyed (FSK) operating at 433 and 868-915 MHz and direct sequence spread spectrum (DSSS) operating at 2.4 GHz band that transmit 802.15.4 and ZigBee standards. The reach of the radios varies from 10 to 100 meters. The antenna configuration can cause transmission rates from 19.2kbps to 240kbps [6]. Currently, the sensor nodes can vary between mode activity, inactivity (idle) and low consumption (sleep) in order to save energy. The energy issue is important because most of sensor nodes are powered by batteries. Nowadays, the main sensor nodes available are LOTUS, IRIS, MICAz, Mica2, and TELOSB CRICKET.

Figure 2 illustrates the actual format of sensor nodes such as IRIS TelosB and MicaZ. During the development of this work were not found Brazilian companies that commercialize sensor nodes. A budget held in the Chinese company Mensic3 in jan/2012 showed that a Micaz cost U\$ 114.00 and a TelosB U\$ 160.00, excluding import duties also should be minimum purchases of U\$ 1000.00.

**Figure 2.** Sensors [6]
