p-Blend: Privacy- and Utility-Preserving Blendshape Perturbation Against Re-Identification Attacks in Virtual Reality
Bibliographic record
Abstract
In this paper, we propose p-Blend, an efficient and effective blendshape perturbation mechanism designed to defend against both intra- and cross-app re-identification attacks in virtual reality. p-Blend provides privacy protection when streaming blendshape data to third-party applications on VR devices. In its design, we consider both privacy and utility. p-Blend not only perturbs blendshape values to resist re-identification attacks but also preserves the smoothness of facial animations and the naturalness of facial expressions, ensuring the continued usability of the data. We validate the effectiveness of p-Blend through extensive empirical evaluations and user studies. Quantitative experiments on a large-scale dataset collected from 45 participants demonstrate that p-Blend significantly reduces re-identification accuracy across a range of machine learning models. While pure-random perturbation fails to prevent attacks that exploit statistical features, p-Blend effectively mitigates these risks in both raw and statistical blendshape data. Additionally, user study results show that facial animations generated from p-Blend-perturbed blendshapes maintain greater smoothness and naturalness compared to those using purely random perturbation. The codes and dataset are available at https://github.com/jingwei1016/p-Blend.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.016 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.006 |
| Open science | 0.002 | 0.007 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".