Abstract
A delay tolerant network is a highly constrained networking environment which is low in resources such as memory, bandwidth and battery power. In opportunistic DTNs, nodes cooperatively forward packets for each other through the carry-store-and-forward paradigm. Opportunistic data forwarding can be abused by an adversary by injecting spurious packets in order to waste the resources of the network. To guard against such attacks, it is important to authenticate packets at intermediate nodes. Packet authentication in itself comes with overheads such as computation cost and energy consumption which can be exploited by an attacker to mount a denial of service attack. We propose the use of light-weight DTN-cookies to protect this vital security service from such malicious exploitation. We show through simulations that our proposed mechanisms can improve network performance and save considerable amount of power even in the presence of attackers.