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Main Authors: West, Christopher, Vecna, Chowdhury, Raiyan
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2307.13859
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author West, Christopher
Vecna
Chowdhury, Raiyan
author_facet West, Christopher
Vecna
Chowdhury, Raiyan
contents The 2021 Canadian census is notable for using a unique form of privacy, random rounding, which independently and probabilistically rounds discrete numerical attribute values. In this work, we explore how hierarchical summative correlation between discrete variables allows for both probabilistic and exact solutions to attribute values in the 2021 Canadian Census disclosure. We demonstrate that, in some cases, it is possible to "unround" and extract the original private values before rounding, both in the presence and absence of provided population invariants. Using these methods, we expose the exact value of 624 previously private attributes in the 2021 Canadian census disclosure. We also infer the potential values of more than 1000 private attributes with a high probability of correctness. Finally, we propose how a simple solution based on unbounded discrete noise can effectively negate exact unrounding while maintaining high utility in the final product.
format Preprint
id arxiv_https___arxiv_org_abs_2307_13859
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Random (Un)rounding : Vulnerabilities in Discrete Attribute Disclosure in the 2021 Canadian Census
West, Christopher
Vecna
Chowdhury, Raiyan
Cryptography and Security
The 2021 Canadian census is notable for using a unique form of privacy, random rounding, which independently and probabilistically rounds discrete numerical attribute values. In this work, we explore how hierarchical summative correlation between discrete variables allows for both probabilistic and exact solutions to attribute values in the 2021 Canadian Census disclosure. We demonstrate that, in some cases, it is possible to "unround" and extract the original private values before rounding, both in the presence and absence of provided population invariants. Using these methods, we expose the exact value of 624 previously private attributes in the 2021 Canadian census disclosure. We also infer the potential values of more than 1000 private attributes with a high probability of correctness. Finally, we propose how a simple solution based on unbounded discrete noise can effectively negate exact unrounding while maintaining high utility in the final product.
title Random (Un)rounding : Vulnerabilities in Discrete Attribute Disclosure in the 2021 Canadian Census
topic Cryptography and Security
url https://arxiv.org/abs/2307.13859