Secure and Efficient Mix-Nets
Name
Janno Siim
Abstract
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 shuffl ed 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 e fficiently proving that shuffl ing 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 shuffl e argument proposed by J. Furukawa in 2005.
Firstly, we provide a more detailed and easily readable description of the shuffl e and shuffl e-decryption zero-knowledge protocols than in the original paper. Secondly, we provide two new characterizations of a permutation matrix and two simple modi cations of
the shuffl e protocol that reduce the computational complexity.
Major challenge of constructing mix-nets lies in e fficiently proving that shuffl ing 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 shuffl e argument proposed by J. Furukawa in 2005.
Firstly, we provide a more detailed and easily readable description of the shuffl e and shuffl e-decryption zero-knowledge protocols than in the original paper. Secondly, we provide two new characterizations of a permutation matrix and two simple modi cations of
the shuffl e protocol that reduce the computational complexity.
Graduation Thesis language
English
Graduation Thesis type
Master - Computer Science
Supervisor(s)
Helger Lipmaa
Defence year
2016