Detecting LLM-Assisted Academic Dishonesty using Keystroke Dynamics

The rapid adoption of generative AI tools has intensified the challenge of maintaining academic integrity. Conventional plagiarism detectors, which rely on text-matching or text-intrinsic features, often fail to identify submissions that have been AI-assisted or paraphrased. To address this limitation, we introduce keystroke-dynamics-based detectors that analyze how, rather than what, a person writes to distinguish genuine from assisted writing. Building on our earlier study, which collected keystroke data from 40 participants and trained a modified TypeNet model to detect assisted text, we expanded the dataset by adding 90 new participants and introducing a paraphrasing-based plagiarism-detection mode. We then benchmarked two additional gradient-boosting classifiers, LightGBM and CatBoost, alongside TypeNet, and compared their performance with DetectGPT, LLaMA 3.3 70B Instruct, and the results of 44 human evaluators. To further assess and improve robustness, we proposed a deception-based threat model simulating forged keystrokes and applied adversarial training as a countermeasure. Results show that the machine learning models achieve F1 scores above 97% in structured settings, while TypeNet performs best in detecting paraphrasing, with an F1 score of 86.9%. In contrast, text-only detectors and human evaluators perform near-chance, demonstrating that keystroke dynamics provide a strong behavioral signal for identifying AI-assisted plagiarism and support the use of multimodal behavioral features for reliable academic integrity assessment.