The Current State of Cryptographic Election Protocols

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The Current Stateof CryptographicElection
Protocols
Josh Benaloh Microsoft Research
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So, you want to hold an election
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Fundamental Decision

• You have essentially two paradigms to choose from
  
• Anonymized Ballots
• Ballotless Tallying

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Anonymized Ballots
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Ballotless Tallying
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A Fundamental Trade-Off

• Ballots simplify write-ins and other
  non-standard options.
• Non-standard options can compromise privacy.

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The Mix-Net Paradigm
Chaum (1981)
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The Mix-Net Paradigm
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The Mix-Net Paradigm
Vote
MIX
Vote
Vote
Vote
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The Mix-Net Paradigm
Vote
MIX
Vote
Vote
Vote
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The Mix-Net Paradigm
Vote
MIX
MIX
Vote
Vote
Vote
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The Homomorphic Paradigm
Benaloh (Cohen), Fischer (1985)
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The Homomorphic Paradigm
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The Homomorphic Paradigm
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Some Principles of Election Protocols

• Privacy
• Verifiability
• Robustness
• Coercibility

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Privacy

• Only one voter?
• A unanimous tally?
• Unanimous less one?
• Copy cats?
• Free-form ballots?

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Verifiability

• By single trusted party?
• By trusted committee?
• By each voter?
• By observers?

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Robustness

• Against faulty/malicious voter?
• Against faulty/malicious trustee?
• At what cost to privacy?

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Coercibility

• Before the vote?
• During the vote?
• After the vote?
• By trustee, voter, or observer?
• Free-form ballots?

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Some of the Authors

• Mix-Net Chaum, Fujioka, Okamoto, Ohta,
  Pfitzmann, Waidner, Park, Itoh, Kurosawa,
  Michels, Horster, Sako, Kilian, Abe, Hirt,
  Jakobsson, Juels, Rivest, Furukawa, Neff, Golle,
  Zhong, Boneh
• Homomorphic Benaloh, Fischer, Yung, Tuinstra,
  Sako, Kilian, Franklin, Cramer, Gennaro,
  Schoenmakers, Hirt, Kiayias

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And the winner is

• The new robust mix-net protocols are practical
  and offer the most flexibility.
• Much recent work has concentrated on efficiency
  improvements.
• Issues remain concerning receipts and coercion.
• Practical concerns focus on authentication and
  system integrity.