Voting Security Overview

1. (Electronic) Voting Security Ben Adida Harvard University Workshop on Electronic Voting IDC Herzliya 17 May 2009

2. The Point of An Election

3. The Point of An Election “The People have spoken.... the bastards!” Dick Tuck 1966 Concession Speech

4. The Point of An Election “The People have spoken.... the bastards!” Dick Tuck 1966 Concession Speech Provide enough evidence to convince the loser.

5. quot;That's for me and a button to know.quot; Joe, the plumber.

15. Fashionable Voting http://www.cs.uiowa.edu/~jones/voting/pictures/7

22. Fashionable Voting 8

23. Fashionable Voting 8

24. Voting is a fundamentally difﬁcult problem. 9

25. Wooten got the news from his wife, Roxanne, who went to City Hall on Wednesday to see the election results. quot;She saw my name with zero votes by it. She came home and asked me if I had voted for myself or not.quot; 10

26. 14 12

27. 14 12 1 person, 1 vote

28. Enforced Privacy to ensure each voter votes in his/her own interest 12

29. http://www.cs.uiowa.edu/~jones/voting/pictures/ 13

30. 1892 - Australian Ballot http://www.cs.uiowa.edu/~jones/voting/pictures/ 14

31. The Ballot Handoff McCain Alice the Voter 17

35. The Ballot Handoff McCain Obama Obama Obama McCain McCain McCain Alice the Voter 17

36. The Ballot Handoff McCain Obama Obama Obama McCain McCain McCain Alice the Voter Black Box 17

37. Chain of Custody 18

38. Chain of Custody /* 1 * source * code */ if (... Vendor 18

39. Chain of Custody /* 1 * source * code Voting 2 */ Machine if (... Vendor 18

40. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 18

41. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice 18

42. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice 18

43. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice 5 Ballot Box Collection 18

44. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice Results 5 6 ..... Ballot Box Collection 18

45. Chain of Custody /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice Results 5 6 ..... Ballot Box Collection Black Box 18

46. The Cost of Secrecy

51. But Secrecy is Important. Secret Ballot implemented in Chile in 1958. “the secrecy of the ballot [...] has ﬁrst-order implications for resource allocation, political outcomes, and social efﬁciency.” [BalandRobinson 2004]

52. Because we care about a meaningful result, we’ve made auditing very difﬁcult. 21

53. We are left chasing evidence of correctness. Meanwhile we destroy evidence on purpose. 22

54. Obtaining Evidence /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor 4 Alice Results 5 6 ..... Ballot Box Collection 23

55. Obtaining Evidence /* 1 * source * code Polling Voting */ 3 2 Location Machine if (... Vendor - source code audit - Logic & Accuracy - Parallel Testing - Voter-Veriﬁed Paper Audit Trail

56. Obtaining Evidence Polling Location 3 - Multiple poll watchers competing afﬁliations - No personal 4 Alice electronic devices at the polling station - Logging all events

57. Obtaining Evidence - redundant counts - ballot box seals - statistical auditing by partial recounts Results 5 6 ..... Ballot Box Collection

58. Fragmented, Adversarial and Indirect - each piece of evidence covers a small segment of the chain. - attacker knows the checks, and can try to sneak in where the chain is not covered. - to maintain security and for practical purposes, the evidence is very indirect.

59. The Effect of DREs - More to audit - Errors can have disproportionate effects - Software is not just for speed/efﬁciency, it becomes central for integrity.

60. Software Independence an undetected mistake in the system does not cause an undetectable error in the tally.

61. Can we get more direct, more end-to-end evidence?

62. Secret Ballot vs. Veriﬁability Voting System convince Alice Carl the Coercer 31

63. Secret Ballot vs. Veriﬁability Voting System convince Alice Carl the Coercer [Chaum81], [Benaloh85], [PIK93], [BenalohTuinstra92], [SK94], [Neff2001], [FS2001], [Chaum2004], [Neff2004], [Ryan2004], [Chaum2005] Punchscan, Scantegrity I & II, Civitas, ThreeBallot, Prêt-à-Voter, Scratch & Vote, ... 31

64. Public Ballots Bulletin Board Bob: McCain Carol: Obama 32

65. Public Ballots Bulletin Board Bob: McCain Carol: Obama Alice 32

66. Public Ballots Bulletin Board Alice: Bob: Obama McCain Carol: Obama Alice 32

67. Public Ballots Bulletin Board Alice: Bob: Obama McCain Carol: Obama Tally Obama....2 McCain....1 Alice 32

68. Encrypted Public Ballots Bulletin Board Alice: Bob: Rice Clinton Carol: Rice Tally Obama....2 McCain....1 Alice 33

69. Encrypted Public Ballots Bulletin Board Alice: Bob: Rice Clinton Carol: Ali Rice ce ver Tally iﬁes he rv Obama....2 ote McCain....1 Alice 33

70. Encrypted Public Ballots Bulletin Board Alice: Bob: Rice Clinton Carol: Ali ce Rice ta lly ver e thTally iﬁes riﬁes ve he rv eryone ote E v Obama....2 McCain....1 Alice 33

71. End-to-End Veriﬁcation

72. End-to-End Veriﬁcation /* * source * code Voting */ Machine if (... Vendor Polling Location

73. End-to-End Veriﬁcation /* * source * code Voting */ Machine if (... Vendor Ballot Box / Polling Bulletin Board Location Alice

74. End-to-End Veriﬁcation /* * source * code Voting */ Machine if (... Vendor Ballot Box / Results Polling Bulletin Board Location ..... Alice

75. End-to-End Veriﬁcation /* * source * code Voting */ Machine if (... Vendor Ballot Box / Results Polling Bulletin Board Location ..... 1 Alice Receipt

76. End-to-End Veriﬁcation /* * source * code Voting */ Machine if (... Vendor Ballot Box / Results Polling Bulletin Board Location ..... 1 2 Alice Receipt

77. Open-Audit Elections

78. Evidence-Based Elections

79. Questions? ben_adida@harvard.edu