Mixnets and Verifiable Shuffling

In this thesis we consider different mix network protocols. First, we discuss a protocol called cMix. We describe the concept of verifiable shuffling, that enable mixnodes to prove that they operate correctly according to the protocol. We present three protocols for verifiable shuffling a list of encrypted elements, the Naive protocol, the Simple n-shuffle and the Permutation matrix protocol. The first two make use of the fact that polynomials remain invariant under permutation of their roots, and the last makes use of a permutation matrix. We discuss security achieved in all of our protocols, and explain how many exponentiations they require