Lagrangian E-Voting: 
              Verifiability on Demand and Strong Privacy

              Lukasz Krzywiecki, Miroslaw Kutylowski
            Institute of Mathematics and Computer Science 
                  Wroclaw University of  Technology


We propose a new approach to verifiability of Internet e-voting procedures: 
correct counting of each single ballot  can be checked, but verification 
is a zero-knowledge court procedure. After verification period is over, 
certain  keys are destroyed and breaking  vote privacy becomes substantially
harder. 

Our main goal is to provide a framework for the political situation in which
the voters are more concerned about disclosure of their preferences than about
the correctness of the results. Our approach also responds to threats of coercion 
exercised by a~physically present coercer. 

Our approach can be used on top of the previous schemes such as SC\&V to improve 
their security features. It is limited to the cases when the voters hold 
electronic ID cards.


Keywords: Internet e-voting, electronic ID card, 
anonymity, verifiability, Lagrangian interpolation, zero-knowledge proof, 
undeniable signature

Partially supported by Polish Ministry of Science and Higher Education, 
grant  N N206  2701 33