Smartphone Touchscreens Leak Handwriting via Electromagnetic Side Channel
A significant security flaw has been identified in capacitive touchscreens, as researchers have shown that electromagnetic (EM) emissions produced while writing on smartphones can be intercepted and reconstructed into identifiable two-dimensional paths. The attack method, referred to as TESLA (Touchscreen Electromagnetic Side-channel Leakage Attack), employs a non-contact technique to capture EM signals from on-screen writing, converting them into real-time continuous handwriting. In experiments conducted on various commercial off-the-shelf (COTS) smartphones, TESLA achieved a character recognition accuracy of 77% and a Jaccard index of 0.74, reflecting a strong resemblance to the original handwriting. These results were published in the Cryptography and Security section of arXiv (ID 2512.11484), revealing a new side-channel vulnerability for touchscreen devices.
Key facts
- TESLA attack recovers handwriting trajectories from EM emanations of capacitive touchscreens.
- Non-contact framework captures EM signals during on-screen writing.
- Achieves 77% character recognition accuracy on COTS smartphones.
- Jaccard index of 0.74 for trajectory similarity.
- Published on arXiv under Computer Science > Cryptography and Security.
- Paper ID: 2512.11484.
- Exploits electromagnetic side channel of touchscreens.
- Real-time reconstruction of 2D handwriting trajectories.
Entities
Institutions
- arXiv