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Kickoff Meeting „ E-Voting Seminar“. An Introduction to Cryptographic Voting Systems Prof. Andreas Steffen Hochschule für Technik Rapperswil andreas.steffen@hsr.ch. Cryptographic Voting Systems . Summary of my talk:.

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kickoff meeting e voting seminar
Kickoff Meeting „E-Voting Seminar“

An Introduction toCryptographicVoting Systems

Prof. Andreas Steffen

Hochschule für Technik Rapperswil

andreas.steffen@hsr.ch

cryptographic voting systems
Cryptographic Voting Systems

Summary of my talk:

  • Due to repeatedfailures and detectedvulnerabilities in bothelectro-mechanical and electronicvotingmachines, votershavesomehow lost faiththattheoutcome of a poll alwaysrepresentsthetrue will of theelectorate.
  • Even moreuncertainiselectronicvotingoverthe Internet whichispotentiallyprone to coercion and vote-selling (thisdoesn‘tseem to be an issue in Switzerland).
  • Manual counting of paperballotsis not really an option in the21stcentury and is not freefromtamperingeither.
  • Modern cryptographicvotingsystemsallowtrueend-to-endverification of thecompletevotingprocessbyanyindividualvoter, withoutsacrificingsecrecy and privacy.
losing trust in electronic voting systems
Losing Trust in Electronic Voting Systems

2006 - The Morning Call:

Voter smashes DRE in

Allentown with metal cat

2006 - Princeton study on Diebold DRE:

Hack the vote? No problem

March 3 2009 - Germany:

Bundesverfassungsgericht

bansunverifiableE-voting

2006 - Dutch ES3B voting machines:

Hacked to play chess

e voting in my home town schlieren
E-Voting in myhometown Schlieren

Hidden PIN

„Internet-basedvotingdoes not havetobemoresecure as voting per snailmail“

Justice Department of theCanton of Zurich

in security features
[In]Security Features

???

ProtectionfromMan-in-the-Middleattacks

conclusion
Conclusion

So what?

„Youare not allowed to know. Theexacttransactionprocessingiskeptsecretdue to securityreasons“Justice Department of theCanton of Zurich

traditional chain of custody security
Traditional Chain-of-Custody Security

Software Verification

Sealing

Tallying

Verification by proxy only

Source: Ben Adida, Ph.D. Thesis 2006

desirable end to end verification by voter
Desirable: End-to-End Verification by Voter

Secrecy?

Privacy?

Source: Ben Adida, Ph.D. Thesis 2006

end to end auditable voting system e2e
End-to-End Auditable Voting System (E2E)
  • Any voter can verify that his or her ballot is included unmodified in a collection of ballots.
  • Any voter (and typically any independent party additionally) can verify [with high probability] that the collection of ballots produces the correct final tally.
  • No voter can demonstrate how he or she voted to any third party (thus preventing vote-selling and coercion).

Source: Wikipedia

solution cryptographic voting systems
Solution: Cryptographic Voting Systems

ThresholdDecryption

Mixnet

A

B

A

B

C

C

ElGamal

/Paillier

Tamper-ProofBulletin Board

HomomorphicTallying

Source: Ben Adida, Ph.D. Thesis 2006

proposed e2e systems
Proposed E2E Systems
  • Punchscan by David Chaum.
  • Prêt à Voter by Peter Ryan.
  • Scratch & Vote by Ben Adida and Ron Rivest.
  • ThreeBallot by Ron Rivest (paper-based without cryptography)
  • Scantegrity II by David Chaum, Ron Rivest, Peter Ryan et al.(add-on to optical scan voting systems using Invisible Ink)
  • Helios by Ben Adida (http://www.heliosvoting.org/)
scratch vote ballot
Scratch & Vote Ballot

Perforation

Encryptpk(256, r1)

Encryptpk(20 , r2)

Encryptpk(228, r3)

Obama

Randomized

candidate list

None

McCain

2D barcode

ElGamal or Paillier

Public Key Encryption

r1

r2

r3

Random Key

Scratch surface

Source: Ben Adida, Ph.D. Thesis 2006

homomorphic counters
Homomorphic Counters

256

00...01

00...00

00...00

One vote for Obama

228

00...00

00...01

00...00

One vote for McCain

20

00...00

00...00

00...01

One vote for None

Obama

McCain

None

00...10

00...01

00...00

Tallying Counter

Multiplication of all encrypted votes with Tallying Counter

accumulates votes in the candidates‘ counters in encrypted form.

Total number of registered U.S. voters < 228 (28 bits)

1024 bit Paillier Public Key Cryptosystem could handle 35 candidates

Source: Ben Adida, Ph.D. Thesis 2006

pre voting verification i

Vote

Audit

Pre-Voting Verification I

McCain

None

Obama

Obama

None

McCain

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

pre voting verification ii

None

Obama

McCain

Vote

Audit

Pre-Voting Verification II

McCain

None

Obama

Obama

None

McCain

r1 r2 r3

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

casting the ballot i
Casting the Ballot I

McCain

Obama

None

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

casting the ballot ii
Casting the Ballot II

McCain

Obama

Ed the

Election Official

None

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

casting the ballot iii

Optical

Scanner

Keep as

a receipt

Casting the Ballot III

Ed the

Election Official

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

post voting verification
Post-Voting Verification

Web Bulletin Board

Valerie

Vanessa

Victor

Valerie the Voter

Source: Ben Adida, Ph.D. Thesis 2006

tally and decryption of final result

Obama

McCain

None

00...10

00...01

00...00

Threshold decryption with

shared private key

Democrats

Homomorphic Addition

Republicans

0101101...11100100011

Independents

Encrypted tallying counter

Tally and Decryption of Final Result

Web Bulletin Board

Valerie

Vanessa

Victor

Source: Ben Adida, Ph.D. Thesis 2006

conclusion1
Conclusion
  • Modern Cryptographic Voting Systems allow true end-to-end verification of the whole voting process by anyone while maintaining a very high level of secrecy.
  • Due to the advanced mathematical principles they are based on, Cryptographic Voting Systems are not easy to understand and are therefore not readily accepted by authorities and the electorate.
  • But let‘s give Cryptographic Voting Systems a chance!They can give democracy a new meaning in the 21st century!