Energy-efficient, secure group key agreement for ad hoc networks

Public key cryptography is well-suited to ad hoc networks as it requires no a priori secure key distribution mechanism. Recent advances in lattice-based cryptography are enabling the use of public key algorithms (PKAs) in low-power devices. Unfortunately, while many ad hoc networking applications are dominated by multicast traffic, PKAs are inherently unicast: public/private key pairs are generated by data destinations. To fully realize public key cryptography in ad hoc networks, low-power PKAs must therefore be augmented with energy-efficient mechanisms for secure group key establishment. Motivated by recent results on information theoretic secrecy, we present a protocol that generates keys for t-sized multicast groups with O(log_bt) transmissions, where b is a parameter that enables trades between energy efficiency and security. Extensions of this protocol that exploit network topology side information and which permit multilevel security are also described. A cryptosystem employing an energy-efficient PKA and the protocols presented herein could provide the benefits of public key cryptography - i.e., dynamic ad hoc network support - with features currently found only in symmetric systems.