Efficient Multicast Stream Authentication for the Fully Adversarial Network Model

We consider the stream authentication problem when an adversary has the ability to drop, reorder or inject data inthe network. We propose a coding approach for multicast stream authentication using the list-decoding property of Reed-Solomon codes. We divide the data to be authenticated into a stream of packets and associate a single trapdoor hashcollision for every λn packets where λ and n are predesignated parameters. Our scheme, which is also joinable at theboundary of any n-packet block, can be viewed as an extension of Lysyanskaya, Tamassia and Triandopoulos’s techniquein which λ = 1. We show that by choosing λ and n appropriately, our scheme outperforms theirs in time spent forprocessing data at the sender and receiver.Our approach relies on the dispersion process as SAIDA and eSAIDA. Assuming that we use RSA for signing and SHA-256 for hashing, we give an approximation of the proportion of extra packets per block which could be processed via ourtechnique with respect to the previous schemes. As example when we process λ = 1000 blocks of 2650 64-byte-packets,the gain of our scheme with respect to Lysyanskaya et al.’s is about 30%.