## 5 M2M Security
\begin{table}
\begin{tabular}{l l l} \hline \hline - & Security technologies & - & 16 channel hopping \\ of ZigBee & - & Key establishment, key transport, frame \\ - & Authentication, encryption, & protection, ad device management \\ integrity checking, & & implemented mostly at the network (NWK) \\ countermeasures & & and application support \\ against replay-attacks. & & sub-layer (APS). \\  & ZigBee Alliance & - & AES-CCM to offer confidentiality and \\  & & authentication, AES-CBC-MAC to offer \\  & & authentication or AES-CTR to offer \\  & & confidentiality. 32-, 64-, or 128-bit MAC and \\  & & 128-bit key. \\  & & - & Key sequence counter \\ \hline Security technologies of ZigBee & & - & 3 channel hopping \\ RF4 CE (Even lower power and & & - & Simpler pairing mechanism than in ZigBee \\ simplified version of ZigBee) & & - & AES-CCM with 128-bit key. \\ \hline - & Security technologies of Wi-Fi & - & WPA2 that uses Counter Mode with Cipher Block \\ - & Authentication, encryption, & & Chaining Message Authentication Code Protocol \\  & integrity, replay protection & & (CCMP) based on 128-bit AES-CCM block cipher \\  & & - & Cryptographic hash function \\  & & - & Key management \\  & & - & Replay protection \\  & & - & WPA2 can be used in two modes: \\  & & - & Shared key: relying upon the use of a key shared by \\  & & & all Wi-Fi clients and access point. \\  & & - & Enterprise, relying upon the use of an external \\  & & AAA server \\ \hline - & Default security technologies of & - & 32-bit KILL and ACCESS passwords \\  & EPCglobal UHF Class 1 & - & (perma)locking of memory \\  & Generation 2(v1.2.0) RFID tags & EPCglobal & - \\ - & To prevent unauthorized & & \\ writing and disabling and & & & \\ counterfeiting of RFID tags. & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._The security of group communications is an important problem that has been addressed for more than a decade. Most of the research efforts focused on conventional Internet (_i.e._, Internet Multicasting) both in the wired and wireless environments (e.g., [129, 130, 131]). Protocol scalability and the security-performance tradeoff are the major concerns in the group communications security topic. Furthermore, a number of standards have emerged in the IETF [132], and some of them have even been adopted by a number of technology standardization bodies (e.g., 3 GPP's MBMS [133] and ETSI's SES [134]). Group communication security is particularly important in the WSN context when implementing end to end security given the critical resources of WSN networks (CPU, memory, battery, and bandwidth) (e.g., [135, 136, 137, 138]). If the data has to be secured from the source, then it is quite important to send a single protected data stream from the device. Unfortunately, asymmetric cryptographic techniques usually involve ciphering the data stream with the public key of the receiver, creating the need for redundant data transmission, which in the case of WSN creates an unbearable load upon the device. Group communication security techniques must therefore be used, involving the distribution of a group key to all parties involved in the communication scheme. The other aspect that needs to be considered in M2M is the interoperability problem due to network heterogeneity in terms of capacity (e.g., WAN _vs._ LAN) and supported protocols. This interoperability problem requires defining dynamic configuration mechanisms and adaptive protocols to ensure end-to-end security for M2M group communications. Finally, most of the M2M devices are involved in applications producing or consuming data which need to be secured from the source to the destination, either using hop by hop or end-to-end security. This is addressing \"application domain security\", and the application providers or the M2M service providers are typically responsible to manage the associated credentials.