Secure and Efficient Mix-Nets

Janno Siim
Mix-net is a system that can provide anonymity in a computer network. Mix-net takes as an input user's ciphertexts and outputs them in a shuffled order. Secure e-voting and variety of other applications can be built on top of mix-net architecture.

Major challenge of constructing mix-nets lies in efficiently proving that shuffling was done correctly. Mix-net cannot reveal the permutation because that would break the anonymity. One solution is to provide a zero-knowledge proof.

This thesis studies a zero-knowledge shuffle argument proposed by J. Furukawa in 2005.

Firstly, we provide a more detailed and easily readable description of the shuffle and shuffle-decryption zero-knowledge protocols than in the original paper. Secondly, we provide two new characterizations of a permutation matrix and two simple modications of
the shuffle protocol that reduce the computational complexity.
Graduation Thesis language
Graduation Thesis type
Master - Computer Science
Helger Lipmaa
Defence year