{"slug": "locality-sensitive-hashing-and-privacy", "title": "Locality-Sensitive Hashing and Privacy", "summary": "A new study by researchers (submitted on 27 Feb 2023) demonstrates that locality-sensitive hashing does not guarantee privacy, presenting attacks against Google's FLoC and the MinHash Hierarchy system. The attacks refute pre-image resistance, anonymity, and privacy claims, showing that for FLoC, 10% or more of browsing history can be reconstructed for 30% of users using Generative Adversarial Networks, and for MinHash, user movement can be limited to just 10% of the possible geographic area.", "body_md": "# Computer Science > Cryptography and Security\n\n[Submitted on 27 Feb 2023]\n\n# Title:Locality-Sensitive Hashing Does Not Guarantee Privacy! Attacks on Google's FLoC and the MinHash Hierarchy System\n\n[View PDF](/pdf/2302.13635)\n\nAbstract:Recently proposed systems aim at achieving privacy using locality-sensitive hashing. We show how these approaches fail by presenting attacks against two such systems: Google's FLoC proposal for privacy-preserving targeted advertising and the MinHash Hierarchy, a system for processing mobile users' traffic behavior in a privacy-preserving way. Our attacks refute the pre-image resistance, anonymity, and privacy guarantees claimed for these systems.\n\nIn the case of FLoC, we show how to deanonymize users using Sybil attacks and to reconstruct 10% or more of the browsing history for 30% of its users using Generative Adversarial Networks. We achieve this only analyzing the hashes used by FLoC. For MinHash, we precisely identify the movement of a subset of individuals and, on average, we can limit users' movement to just 10% of the possible geographic area, again using just the hashes. In addition, we refute their differential privacy claims.\n\n### References & Citations\n\nLoading...\n\n# Bibliographic and Citation Tools\n\nBibliographic Explorer\n\n*(*[What is the Explorer?](https://info.arxiv.org/labs/showcase.html#arxiv-bibliographic-explorer))\nConnected Papers\n\n*(*[What is Connected Papers?](https://www.connectedpapers.com/about))\nLitmaps\n\n*(*[What is Litmaps?](https://www.litmaps.co/))\nscite Smart Citations\n\n*(*[What are Smart Citations?](https://www.scite.ai/))# Code, Data and Media Associated with this Article\n\nalphaXiv\n\n*(*[What is alphaXiv?](https://alphaxiv.org/))\nCatalyzeX Code Finder for Papers\n\n*(*[What is CatalyzeX?](https://www.catalyzex.com))\nDagsHub\n\n*(*[What is DagsHub?](https://dagshub.com/))\nGotit.pub\n\n*(*[What is GotitPub?](http://gotit.pub/faq))\nHugging Face\n\n*(*[What is Huggingface?](https://huggingface.co/huggingface))\nScienceCast\n\n*(*[What is ScienceCast?](https://sciencecast.org/welcome))# Demos\n\n# Recommenders and Search Tools\n\nInfluence Flower\n\n*(*[What are Influence Flowers?](https://influencemap.cmlab.dev/))\nCORE Recommender\n\n*(*[What is CORE?](https://core.ac.uk/services/recommender))# arXivLabs: experimental projects with community collaborators\n\narXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.\n\nBoth individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.\n\nHave an idea for a project that will add value for arXiv's community? [ Learn more about arXivLabs](https://info.arxiv.org/labs/index.html).", "url": "https://wpnews.pro/news/locality-sensitive-hashing-and-privacy", "canonical_source": "https://arxiv.org/abs/2302.13635", "published_at": "2026-07-23 03:09:10+00:00", "updated_at": "2026-07-23 03:22:07.062691+00:00", "lang": "en", "topics": ["ai-safety", "ai-ethics", "ai-policy"], "entities": ["Google", "FLoC", "MinHash Hierarchy", "Generative Adversarial Networks"], "alternates": {"html": "https://wpnews.pro/news/locality-sensitive-hashing-and-privacy", "markdown": "https://wpnews.pro/news/locality-sensitive-hashing-and-privacy.md", "text": "https://wpnews.pro/news/locality-sensitive-hashing-and-privacy.txt", "jsonld": "https://wpnews.pro/news/locality-sensitive-hashing-and-privacy.jsonld"}}