Practical Everlasting Privacy
Myrto Arapinis, Véronique Cortier, Steve Kremer, and Mark D. Ryan. Practical Everlasting Privacy. In Proceedings of the 2nd Conference on Principles of Security and Trust (POST'13), pp. 21–40, Lecture Notes in Computer Science 7796, Springer, Rome, Italy, March 2013.
doi:10.1007/978-3-642-36830-1_2
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Abstract
Will my vote remain secret in 20 years? This is a natural question in the context of electronic voting, where encrypted votes may be published on a bulletin board for verifiability purposes, but the strength of the encryption is eroded with the passage of time. The question has been addressed through a property referred to as everlasting privacy. Perfect everlasting privacy may be difficult or even impossible to achieve, in particular in remote electronic elections. In this paper, we propose a definition of practical everlasting privacy. The key idea is that in the future, an attacker will be more powerful in terms of computation (he may be able to break the cryptography) but less powerful in terms of the data he can operate on (transactions between a vote client and the vote server may not have been stored).
We formalize our definition of everlasting privacy in the applied-pi calculus. We provide the means to characterize what an attacker can break in the future in several cases. In particular, we model this for perfectly hiding and computationally binding primitives (or the converse), such as Pedersen commitments, and for symmetric and asymmetric encryption primitives. We adapt existing tools, in order to allow us to automatically prove everlasting privacy. As an illustration, we show that several variants of Helios (including Helios with Pedersen commitments) and a protocol by Moran and Naor achieve practical everlasting privacy, using the ProVerif and the AKiSs tools.
BibTeX
@inproceedings{ACKR-post13,
abstract = {Will my vote remain secret in 20 years? This is a
natural question in the context of electronic
voting, where encrypted votes may be published on a
bulletin board for verifiability purposes, but the
strength of the encryption is eroded with the
passage of time. The question has been addressed
through a property referred to as everlasting
privacy. Perfect everlasting privacy may be
difficult or even impossible to achieve, in
particular in remote electronic elections. In this
paper, we propose a definition of practical
everlasting privacy. The key idea is that in the
future, an attacker will be more powerful in terms
of computation (he may be able to break the
cryptography) but less powerful in terms of the data
he can operate on (transactions between a vote
client and the vote server may not have been
stored).\par We formalize our definition of everlasting
privacy in the applied-pi calculus. We provide the
means to characterize what an attacker can break in
the future in several cases. In particular, we model
this for perfectly hiding and computationally
binding primitives (or the converse), such as
Pedersen commitments, and for symmetric and
asymmetric encryption primitives. We adapt existing
tools, in order to allow us to automatically prove
everlasting privacy. As an illustration, we show
that several variants of Helios (including Helios
with Pedersen commitments) and a protocol by Moran
and Naor achieve practical everlasting privacy,
using the ProVerif and the AKiSs tools.},
address = {Rome, Italy},
author = {Arapinis, Myrto and Cortier, V{\'e}ronique and Kremer, Steve and Ryan, Mark D.},
booktitle = {{P}roceedings of the 2nd {C}onference on {P}rinciples of {S}ecurity and {T}rust (POST'13)},
DOI = {10.1007/978-3-642-36830-1_2},
editor = {Basin, David and Mitchell, John},
month = mar,
pages = {21-40},
publisher = {Springer},
series = {Lecture Notes in Computer Science},
title = {{P}ractical {E}verlasting {P}rivacy},
volume = {7796},
year = {2013},
acronym = {{POST}'13},
nmonth = {3},
url = {https://members.loria.fr/skremer/files/Papers/ACKR-post13.pdf},
}