Robustness and Collision-Resistance of PhotoDNA

PhotoDNA is a widely utilized hash designed to counteract Child Sexual Abuse Material (CSAM). However, there has been a scarcity of detailed information regarding its performance. In this paper, we present a comprehensive analysis of its robustness and susceptibility to false positives, along with fundamental insights into its structure. Our findings reveal its resilience to common image processing techniques like lossy compression. Conversely, its robustness is limited when confronted with cropping. Additionally, we propose recommendations for enhancing the algorithm or optimizing its application. This work is an extension on our paper [21].