Efficient key management protocols for mobile ad hoc networks

In this thesis, novel solutions are proposed for key management issues in mobile ad hoc networks.; Presented Hierarchical Binary Tree (HBT) based model is distributed, self-organizing, scalable and does not employ online key distribution authority or group manager. Two different group authentication and group key establishment protocols are proposed for the users who form an ad hoc group with distributed trust model. Initially proposed protocols are based on public key cryptography and do not use specific algorithm. However, members can establish the keys faster with proposed customized hybrid scheme which combines elliptic curve cryptography, modular squaring operations and secret key encryption algorithm. Proposed HBT based model provides complete backward and forward security in case of modification in membership and it has comparable efficiency to the other HBT based schemes which employ real time key distribution authority.; Mutual authentication and link encryption can be achieved in wireless sensor network only with public key cryptography if there are no pre-distributed keys. However, constraints in resources make fully public key operations not affordable on sensor. Three different authenticated key establishment protocols are proposed with an objective of being respectful to constraints. Sensor needs to make only modular or cyclic convolution multiplications, and expensive public key decryption operation is executed at the data processing station side. Schemes require small size of code and achieve the least sensor processing time in comparison with fully public key cryptography based protocols.