Systems exploiting network coding to increase their throughput suffer greatly from pollution attacks which consist of injecting malicious packets in the network. The pollution attacks are amplified by the network coding process, resulting in a greater damage than under traditional routing. In this paper, we address this issue by designing an unconditionally secure authentication code suitable for multicast network coding. The proposed scheme is robust against pollution attacks from outsiders, as well as coalitions of malicious insiders. Intermediate nodes can verify the integrity and origin of the packets received without having to decode, and thus detect and discard the malicious messages in-transit that fail the verification. This way, the pollution is canceled out before reaching the destinations. We analyze the performance of the scheme in terms of both multicast throughput and goodput, and show the goodput gains. We also discuss applications to file distribution.
The signature scheme in @cite_18 is a homomorphic signature scheme based on Weil pairing over elliptic curves, while the one proposed in @cite_4 is a homomorphic signature scheme based on RSA. For both schemes, intermediate nodes can authenticate the packets in transit without decoding, and generate a verifiable signature of the packet that they have just encoded without knowing the signer's secret key. However, these schemes require one key pair for each file to be verified, which is not practical either.
@cite_18 @cite_4
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This paper presents a practical digital signature scheme to be used in conjunction with network coding. Our scheme simultaneously provides authentication and detects malicious nodes that intentionally corrupt content on the network. Network coding provides the possibility to maximize network throughput and receives various applications in traditional computer networks, wireless sensor networks and peer-to-peer systems. However, the applications built on top of network coding are vulnerable to pollution attacks, in which the compromised forwarders can inject polluted or forged messages into networks. Existing schemes addressing pollution attacks either require an extra secure channel or incur high computation overhead. In this paper, we propose an efficient signature-based scheme to detect and filter pollution attacks for the applications adopting linear network coding techniques. Our scheme exploits a novel homomorphic signature function to enable the source to delegate its signing authority to forwarders, that is, the forwarders can generate the signatures for their output messages without contacting the source. This nice property allows the forwarders to verify the received messages, but prohibit them from creating the valid signatures for polluted or forged ones. Our scheme does not need any extra secure channels, and can provide source authentication and batch verification. Experimental results show that it can improve computation efficiency up to ten times compared to some existing one. In addition, we present an alternate lightweight scheme based on a much simpler linear signature function. This alternate scheme provides a tradeoff between computation efficiency and security.