RIPPLE Authentication for Network Coding

By allowing routers to randomly mix the information content in packets before forwarding them, network coding can maximize network throughput in a distributed manner with low complexity. However, such mixing also renders the transmission vulnerable to pollution attacks, where a malicious node injects corrupted packets into the information flow. In a worst case scenario, a single corrupted packet can end up corrupting all the information reaching a destination. In this paper, we propose RIPPLE, a symmetric key based in-network scheme for network coding authentication. RIPPLE allows a node to efficiently detect corrupted packets and encode only the authenticated ones. Despite using symmetric key based homomorphic Message Authentication Code (MAC) algorithms, RIPPLE achieves asymmetry by delayed disclosure of the MAC keys. Our work is the first symmetric key based solution to allow arbitrary collusion among adversaries. It is also the first to consider tag pollution attacks, where a single corrupted MAC tag can cause numerous packets to fail authentication farther down the stream, effectively emulating a successful pollution attack.