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Main Authors: Marzani, Fatemeh, van Ede, Thijs, Heijenk, Geert, van Steen, Maarten
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.14250
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author Marzani, Fatemeh
van Ede, Thijs
Heijenk, Geert
van Steen, Maarten
author_facet Marzani, Fatemeh
van Ede, Thijs
Heijenk, Geert
van Steen, Maarten
contents An important aspect of crowd monitoring is knowing how many people we are dealing with. Sometimes, knowing the size of a crowd in a single location and at a specific moment is enough. Matters become problematic when counting the same people across dif ferent locations or counting them over longer periods of time. In those cases, we need to identify and later reidentify a person, which immediately leads to privacy concerns. Until recently, solutions have been based on unique identification of carry-on devices, yet privacy improvements have caused transmitted information to be randomized, rendering this technique mostly useless. We propose to use biometric data instead. We introduce a pipeline that counts people based on face recognition, yet without ever being able to reveal the identity of individuals. To count, a camera initially detects a face, extracts its features, and derives an identifier using a fuzzy extractor. The original facial image is then deleted. Identifiers are inserted into homomorphically encrypted Bloom filters. This allows oblivious set membership testing directly on encrypted data, enabling the system to count across locations or across different moments, without revealing any identities. We provide an initial evaluation of our method that shows promising results.
format Preprint
id arxiv_https___arxiv_org_abs_2604_14250
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Head Count: Privacy-Preserving Face-Based Crowd Monitoring
Marzani, Fatemeh
van Ede, Thijs
Heijenk, Geert
van Steen, Maarten
Cryptography and Security
Distributed, Parallel, and Cluster Computing
An important aspect of crowd monitoring is knowing how many people we are dealing with. Sometimes, knowing the size of a crowd in a single location and at a specific moment is enough. Matters become problematic when counting the same people across dif ferent locations or counting them over longer periods of time. In those cases, we need to identify and later reidentify a person, which immediately leads to privacy concerns. Until recently, solutions have been based on unique identification of carry-on devices, yet privacy improvements have caused transmitted information to be randomized, rendering this technique mostly useless. We propose to use biometric data instead. We introduce a pipeline that counts people based on face recognition, yet without ever being able to reveal the identity of individuals. To count, a camera initially detects a face, extracts its features, and derives an identifier using a fuzzy extractor. The original facial image is then deleted. Identifiers are inserted into homomorphically encrypted Bloom filters. This allows oblivious set membership testing directly on encrypted data, enabling the system to count across locations or across different moments, without revealing any identities. We provide an initial evaluation of our method that shows promising results.
title Head Count: Privacy-Preserving Face-Based Crowd Monitoring
topic Cryptography and Security
Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2604.14250