Cooperative Defense Against Pollution Attacks in Network Coding Using SpaceMac

Abstract—Intra-session network coding is known to be vul-nerable to pollution attacks. In this work, first, we introduce a novel homomorphic MAC scheme called SpaceMac, which allows an intermediate node to verify if its received packets belong to a specific subspace, even if the subspace is expanding over time. Then, we use SpaceMac as a building block to design a cooperative scheme that provides complete defense against pollution attacks: (i) it can detect polluted packets early at intermediate nodes and (ii) it can identify the exact location of all, even colluding, attackers, thus making it possible to eliminate them. Our scheme is cooperative: parents and children of any node cooperate to detect any corrupted packets sent by the node, and nodes in the network cooperate with a central controller to identify the exact location of all attackers. We implement SpaceMac in both C/C++ and Java as a library, and we make the library available online. Our evaluation on both a PC and an Android device shows that (i) SpaceMac’s algorithms can be computed quickly ( ∼ 28 µs in C/C++) and efficiently ( ∼ 64 KB in C/C++), and (ii) our cooperative defense scheme has both low computation ( ∼ 190 µs in C/C++) and low communication (∼ 2%) overhead, significantly less than other comparable state-of-the-art schemes. Index Terms—Byzantine attacks, pollution attacks, network coding, attack detection, attack location, homomorphic MAC I