TY - JOUR

T1 - Auditing for privacy in threshold PKE e-voting

AU - Kiayias, Aggelos

AU - Zacharias, Thomas

AU - Zhang, Bingsheng

N1 - This article is (c)2017 Emerald Group Publishing and permission has been granted for this version to appear here. Emerald does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Emerald Group Publishing Limited.

PY - 2017/3/1

Y1 - 2017/3/1

N2 - Purpose This paper aims to investigate the importance of auditing for election privacy via issues that appear in the state-of-the-art implementations of e-voting systems that apply threshold public key encryption (TPKE) in the client such as Helios and use a bulletin board (BB). Design/methodology/approach Argumentation builds upon a formal description of a typical TPKE-based e-voting system where the election authority (EA) is the central node in a star network topology. The paper points out the weaknesses of the said topology with respect to privacy and analyzes how these weaknesses affect the security of several instances of TPKE-based e-voting systems. Overall, it studies the importance of auditing from a privacy aspect. Findings The paper shows that without public key infrastructure (PKI) support or ? more generally ? authenticated BB ?append? operations, TPKE-based e-voting systems are vulnerable to attacks where the malicious EA can act as a man-in-the-middle between the election trustees and the voters; hence, it can learn how the voters have voted. As a countermeasure for such attacks, this work suggests compulsory trustee auditing. Furthermore, it analyzes how lack of cryptographic proof verification affects the level of privacy that can be provably guaranteed in a typical TPKE e-voting system. Originality/value As opposed to the extensively studied importance of auditing to ensure election integrity, the necessity of auditing to protect privacy in an e-voting system has been mostly overlooked. This paper reveals design weaknesses present in noticeable TPKE-based e-voting systems that can lead to a total breach of voters? privacy and shows how auditing can be applied for providing strong provable privacy guarantees.

AB - Purpose This paper aims to investigate the importance of auditing for election privacy via issues that appear in the state-of-the-art implementations of e-voting systems that apply threshold public key encryption (TPKE) in the client such as Helios and use a bulletin board (BB). Design/methodology/approach Argumentation builds upon a formal description of a typical TPKE-based e-voting system where the election authority (EA) is the central node in a star network topology. The paper points out the weaknesses of the said topology with respect to privacy and analyzes how these weaknesses affect the security of several instances of TPKE-based e-voting systems. Overall, it studies the importance of auditing from a privacy aspect. Findings The paper shows that without public key infrastructure (PKI) support or ? more generally ? authenticated BB ?append? operations, TPKE-based e-voting systems are vulnerable to attacks where the malicious EA can act as a man-in-the-middle between the election trustees and the voters; hence, it can learn how the voters have voted. As a countermeasure for such attacks, this work suggests compulsory trustee auditing. Furthermore, it analyzes how lack of cryptographic proof verification affects the level of privacy that can be provably guaranteed in a typical TPKE e-voting system. Originality/value As opposed to the extensively studied importance of auditing to ensure election integrity, the necessity of auditing to protect privacy in an e-voting system has been mostly overlooked. This paper reveals design weaknesses present in noticeable TPKE-based e-voting systems that can lead to a total breach of voters? privacy and shows how auditing can be applied for providing strong provable privacy guarantees.

KW - Privacy

KW - Auditing

KW - E-Voting

KW - Helios

KW - Man-in-the-middle

U2 - 10.1108/ICS-07-2016-0056

DO - 10.1108/ICS-07-2016-0056

M3 - Journal article

VL - 25

SP - 100

EP - 116

JO - Information and Computer Security

JF - Information and Computer Security

SN - 2056-4961

IS - 1

ER -