Quantifying

Voter-controlled Privacy

Hugo Jonker

in collaboration with Jun Pang and Sjouke Mauw

Why care about privacy?

A random set of voters

Traditional view on privacy

Works for: vote-privacy, receipt-freeness, coercion-resistance

? ? ?

Privacy ≠ swapping

What could that have been?

- ρ( ) =

- ρ(

- ρ({

) = (ρ( ), ρ( )) ,

}K) = {ρ( )}K if k is known

- ρ({ }K) = if k is unknown01101010101011010011101010110011010110101100101010110111011010101

Choice groups

) =

cg(

}{

Conspiring voters

+ =

+ =

...

How to conspire

{ }kuntappable channels

sees all!

=01101010101011010011101010110011010110101100101010110111011010101

+ k = { }k

Untappable channels? ? ?

Untappable channels

01101010101011010011101010110011010110101100101010110111011010101

01101010101011010011101010110011010110101100101010110111011010101

Effects of coercion

) = cg(

}{–

) =

cg( }{– =?

Plans

• slight extensions to formalism• account for distribution in result• conspiring authorities, defense coalitions• extend to auctions, e-healthcare, …

• Sec ote 2010

Thanks for your attention

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