Re: smartcards, electronic ballots

[Dan Geer]

As seems universally the case in security design, there must
be ugly tradeoffs.  In particular (and without quoting acres
of prior material), the proposed requirements for verifiability
and non-coercibility are at odds and one must yield to the
other.  Paper systems make this tradeoff by, on the one hand,
the polling booth (non-coercibility once within) and, on the
other hand, the supervision of the counting process by opponents
(verifiability by proxy), at a cost of zero technology.  Bettering
this in the real world is challenging.

--dan

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as used here

verfiability
  -- voter may verify that his vote counted as he intended it to count
non-coercibility
  -- voter cannot be compelled to show how he voted, during or after

proposition:
 If the voter can verify, then he can be coerced to do so.
contrapositive:
 If voter cannot be coerced, then he cannot verify.

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