Hierarchical Ring Signatures
      Lukasz Krzywiecki, Miroslaw Kutylowski, Anna~Lauks-Dutka

             Institute of Mathematics and Computer Science
                  Wroclaw University of Technology

We propose an infrastructure for ring signatures. The key property is that 
the size of the ring signatures does not grow with the size of the ring as well as 
the computational effort. For this purpose we require a infrastructure with repository 
of the ring signatures created so far. The algorithm uses the anonymity sets of these 
signatures and merges them in a way typical for ring signatures.