Date Added: Aug 2010
In the model of Perfectly Secure Message Transmission schemes (PSMTs), there are n channels between a sender and a receiver, and they share no key. An infinitely powerful adversary A can corrupt (observe and forge) the messages sent through some subset of n channels. For non-threshold adversaries called Q2, Kumar et al. showed a many round PSMT. In this paper, the authors show round efficient PSMTs against Q2-adevrsaries. They first give a 3-round PSMT which runs in polynomial time in the size of the underlying linear secret sharing scheme.