# Bugs in our Pockets: The Risks of Client-Side Scanning

arXiv: https://arxiv.org/abs/2110.07450 · HTML: https://mlsanity.com/paper/2110.07450/

## Key facts

- Cited by 6 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 14 Oct 2021.

## Built on by (most cited first, 6 of 6)

- [Learning to Break Deep Perceptual Hashing: The Use Case NeuralHash](https://mlsanity.com/paper/2111.06628/) (2021)
- [Law and the Emerging Political Economy of Algorithmic Audits](https://mlsanity.com/paper/2406.11855/) (2024)
- [Exploiting and Defending Against the Approximate Linearity of Apple's NeuralHash](https://mlsanity.com/paper/2207.14258/) (2022)
- [Robustness of Practical Perceptual Hashing Algorithms to Hash-Evasion and Hash-Inversion Attacks](https://mlsanity.com/paper/2406.00918/) (2024)
- [Re-purposing Perceptual Hashing based Client Side Scanning for Physical Surveillance](https://mlsanity.com/paper/2212.04107/) (2022)
- [LURE: a Phase-Labelled Synthetic Corpus of Online-Grooming Exchanges](https://mlsanity.com/paper/2610.15908/) (2026)

## Abstract (arXiv)

Our increasing reliance on digital technology for personal, economic, and government affairs has made it essential to secure the communications and devices of private citizens, businesses, and governments. This has led to pervasive use of cryptography across society. Despite its evident advantages, law enforcement and national security agencies have argued that the spread of cryptography has hindered access to evidence and intelligence. Some in industry and government now advocate a new technology to access targeted data: client-side scanning (CSS). Instead of weakening encryption or providing law enforcement with backdoor keys to decrypt communications, CSS would enable on-device analysis of data in the clear. If targeted information were detected, its existence and, potentially, its source, would be revealed to the agencies; otherwise, little or no information would leave the client device. Its proponents claim that CSS is a solution to the encryption versus public safety debate: it offers privacy -- in the sense of unimpeded end-to-end encryption -- and the ability to successfully investigate serious crime. In this report, we argue that CSS neither guarantees efficacious crime prevention nor prevents surveillance. Indeed, the effect is the opposite. CSS by its nature creates serious security and privacy risks for all society while the assistance it can provide for law enforcement is at best problematic. There are multiple ways in which client-side scanning can fail, can be evaded, and can be abused.