A survey of security issues in wireless sensor networks <s> KEY MANAGEMENT PROTOCOLS <s> We introduce TinySec, the first fully-implemented link layer security architecture for wireless sensor networks. In our design, we leverage recent lessons learned from design vulnerabilities in security protocols for other wireless networks such as 802.11b and GSM. Conventional security protocols tend to be conservative in their security guarantees, typically adding 16--32 bytes of overhead. With small memories, weak processors, limited energy, and 30 byte packets, sensor networks cannot afford this luxury. TinySec addresses these extreme resource constraints with careful design; we explore the tradeoffs among different cryptographic primitives and use the inherent sensor network limitations to our advantage when choosing parameters to find a sweet spot for security, packet overhead, and resource requirements. TinySec is portable to a variety of hardware and radio platforms. Our experimental results on a 36 node distributed sensor network application clearly demonstrate that software based link layer protocols are feasible and efficient, adding less than 10% energy, latency, and bandwidth overhead. <s> BIB001 </s> A survey of security issues in wireless sensor networks <s> KEY MANAGEMENT PROTOCOLS <s> Advances in technology introduce new application areas for sensor networks. Foreseeable wide deployment of mission critical sensor networks creates concerns on security issues. Security of large scale densely deployed and infrastructure less wireless networks of resource limited sensor nodes requires efficient key distribution and management mechanisms. We consider distributed and hierarchical wireless sensor networks where unicast, multicast and broadcast type of communications can take place. We evaluate deterministic, probabilistic and hybrid type of key pre-distribution and dynamic key generation algorithms for distributing pair-wise, group-wise and network-wise keys. <s> BIB002
Key management is a core mechanism to ensure the security of network services and applications in WSNs. The goal of key management is to establish required keys between sensor nodes which must exchange data. Further, a key management scheme should also support node addition and revocation while working in undefined deployment environments. Due to the constraints on sensor nodes, key management schemes in WSNs have many differences with the schemes in ad hoc networks. As shown above, public key cryptography suffers from limitations in WSNs. Thus, most proposed key management schemes are based on symmetric key cryptography. Further, a straight pairwise private key sharing scheme between every pair of nodes is also impractical in WSNs. A pairwise private key sharing scheme requires predistribution and storage of n -1 keys in each node, where n is the number of nodes in a sensor network. Due to the large amount of memory required, pairwise schemes are not viable when the network size is large. Moreover, most key pairs would be unusable since direct communication is possible only among neighboring nodes. This scheme is also not flexible for node addition and revocation. In this section, we discuss key management protocols in WSNs. Another investigation of key management mechanisms for WSNs can be found in BIB002 . Figure 2 shows a taxonomy of key management protocols in WSNs. According to the network structure, the protocols nTable 5. Symmetric key cryptography: average RC5 and skipjack execution times (Source: BIB001 ).