LG. Votebook is a system designed for poll stations only with secured voting machines at public locations, but not for online voting at private locations over the internet.
The Votebook system connects voting machines via a private blockchain. The system enables voters to check their voting. The Votebook team claimed the system fullfills all requirements and it is also realistically feasible.
The voting machines work as blockchain nodes in a Virtual Private Network (VPN). Unlike bitcoin there is no proof of work only a time based mechanism to avoid collisions between nodes adding new blocks to the network. To avoid ballot stuffing there are two blockchains running in parallel way: a ledger of votes and a ledger of voters.
The blocks on this chain will consist of a list of hashed voter IDs processed by the machine, a hash of the previous block on the ledger, and a hash of the proposed block that is encrypted with the voting machine’s private key. There is a risk of an adversary lining up voter blocks with vote blocks to allow statistical inferences about a given voter’s choice. Thus in addition to scrambling the order of voters in the block, the voter ledger must also be kept private and never released. To preserve privacy, the nodes encrypt the voter IDs with a symmetric key from the election authority.
On my mind Votebook is a possible solution addressing the problems of voting machines at general elections. Further analysis will follow if more details or the source code are published.
Link to proposal: http://www.economist.com/sites/default/files/nyu.pdf.