Re: [Belenios-discuss] Randomization at the Voting Device in BeleniosVS

[Véronique Cortier <veronique.cortier AT loria.fr>]

Dear Tejaswi,

You are right, receipt-freeness can be guaranteed if just the
voting-server re-randomizes the ballot before publishing it.

However, the randomization by the voting device is here to protect
voter's privacy against the Registrar. Indeed, the Registrar knows the
correspondence between the originally encrypted ballot enc(v,r,pk) and
the vote v in clear. Suppose now that the Registrar is malicious and
observes the communication from the voter (and her voting device). If he
sees that Alice sends enc(v,r,pk) to the voting server, he learns that
Alice has voted v. So instead, the voting device re-randomizes the
ballot, sending enc(v,r',pk) to the voting server.

I hope this answers your question.
Kind regards,
Veronique.


Le 12/08/2019 à 15:55, Tejaswi Nadahalli a écrit :
> In the BeleniosVS paper, it's mentioned that Ballots will be
> re-randomised both by the voting device and the voting server.
> Why does it need to be re-randomized by the voting-device?
> Receiptfreeness can be guaranteed if just the voting-server
> re-randomizes the ballot before publishing it on the public bulletin board.
> What am I missing?
> 
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