Pollution Attack Resistance Dissemination in VANETs Based on Network Coding

Network coding is widely used in the dissemination schemes of VANETs, because it can improve the network throughput. However, it will bring the pollution attack into the network, making the decoding procedure error, so vehicles can not recover the original file. Therefore, we need adopt a signature scheme to validate a piece without decoding. In the current signing schemes, the linear subspace signature scheme is to defend the pollution attack. But the length of the signature equal to the piece size required several packets to be transmitted together. Moreover, even one lost packet or polluted packet may make the whole piece dropped including the unpolluted packets, causing the limited resources to be wasted. In this paper, we adopt the padding scheme, obtain a packet-size vector which is orthogonal to linear space spanned by all packets in a generation and sign the vector, reducing the length of the signature into packet size and more importantly validating coded packets other than coded pieces in a generation. The simulation shows that our scheme has higher downloading rate, and lower downloading delay.