Research

Progress Report: Postscript

Extensions to the Paillier Cryptosystem

The article:
I. Damgaard, and M. Jurik: A Generalisation, a Simplification and some Applications of Paillier's Probabilistic Public-Key System, to be presented at PKC 2001.

Is Available in Postscript

Cryptosystem Implementation

Some source code implementing the cryptosystem is also available:

Makefile - for compiling.
Cryptosystem.java - A Java class with the system.
Test.java - A Small test program.

Small Example Voting System

Some source code implementing a CGI-service with a 2 candidate vote system:

Documents.bigdoc - The html documents used in voting.wig.
Generate.java - Small java program to generate the numbers that are inserted in voting.wig.
Interface.java - The java interface which just makes the BigInteger computations needed.
RIPEMD160.java - My own implementation of the RIPEMD160 hash function.
RIPETEST.java - A test that the RIPEMD160 actually does what's it's supposed to.
interface.c - C Interface to interface between java and bigwig.
interface.h - The header file for the C Interface.
voting.wig - The voting service written in bigwig.
Applet/Voting.java - The applet for the client side computations.
Applet/bigwigApplet.java - a bigwigApplet that is needed to communicate with bigwig.

Known Problems:

The applet crashes netscape 4.7 on Mac.
Problems using JNI on Linux with JDK1.3 due to error in Hotspot engine.
Problems with name conflict in Bigwig/JNI in versions up to 1.4.2.

Old Voting System

This is an old version implementing the voting system with linear proofs, and few optimisations. The Source code:

DecodingShare.java - Data Structure for holding decryption shares and proof of correctness.
Vote.java - Data Structure for holding votes and proof of correctness.
PublicKey.java - Data Structure for holding a public key.
SecretDistributedKey.java - Data Structure for holding a key share of a private key.
SecretKey.java - Data Structure for holding a private key.
Trusted.java - The functionality of the trusted 3rd party responsible for making the keys.
Tally.java - The functionality of the tally servers responsible for calculating the decoding shares.
Voter.java - The Voter functionality for making votes.
Result.java - The functionality for calculating the result from the shares.
Makefile - The makefile.
test2.java - Small test Program.
Exception/IllegalVote.java - The following are exceptions thrown at different places due to problems with input to methods.
Exception/NoLegalVotes.java
Exception/NotEnoughTallies.java
Exception/WrongLength.java