Abstract
At PODC'05, Subramanian, Katz, Roth, Shenker and Stoica (SKRSS) introduced and formulated a new theoretical problem called reliable broadcast problems in unknown fixed-identity networks [3] and further proposed a feasible result to this problem. Since the size of signatures of a message traversing a path grows linearly with the number of hops in their implementations, this leaves an interesting research problem (an open problem advertised by Subramanian et al in [3]) - how to reduce the communication complexity of their reliable broadcast protocol?.
In this paper, we provide a novel implementation of reliable broadcast problems in unknown fixed-identity networks with lower communication complexity. The idea behind of our improvement is that we first transfer the notion of path-vector signatures to that of sequential aggregate path-vector signatures and show that the notion of sequential aggregate path-vector is a special case of the notion of sequential aggregate signatures. As a result, the currently known results regarding sequential aggregate signatures can be used to solve the open problem. We then describe the work of [3] in light of sequential aggregate signatures working over independent RSA, and show that if the size of an node vi,j's public key vertical bar g(v(i,j))vertical bar is t(i,j) and the number of hops in a path p(i) is d(i) in the unknown fixed-identity graph G (with k adversaries), the reduced communication complexity is approximate to Sigma(di-1)(j=1) t(i,j) while the computation (time) complexity of our protocol is the same as that presented in [3].