# Facial Privacy Protection with Dynamic Multi-User Access Control for Online Photo Platforms
## 6 Conclusions  
This paper presents a facial privacy protection system designed as a proactive measure to protect facial data in shared images. The system encrypts facial regions before an image is published, ensuring privacy at the source before others can access it. Building on our previous work on a single-party face protection system, SnapSafe, this study introduces a file-level facial protection mechanism with dynamic multi user access control. The proposed system categorizes users into two roles: image owners, who upload and manage images, and image consumers, who request access to protected facial data. Image owners can grant or revoke access to specific consumers, ensuring controlled facial data sharing through access limitations and an encryption-based permission system. The system employs key splitting for secure access control, an owner-centric permission model for granting and revoking access, and a request-based mechanism that allows consumers to request facial data access, subject to owner approval. During the evaluation, the system was tested with varying numbers of faces, categorized into single, small, medium, and large groups. Results demonstrate the system's efficiency in safeguarding facial data while ensuring seamless access in multi-user environments. The encryption of facial data was completed in an average time of less than 350 ms, measured from the request to the response of the server, reflecting real-world performance when network variability is excluded. The system maintained a 100% success rate in key-splitting operations across all group sizes, ensuring secure access sharing. Facial data decryption for both image owners and consumers was averaged under 286 ms, while revocation operations were efficiently processed with average server response times below 16 ms. These results highlight the system's ability to balance security and usability for facial data protection. For future work, we aim to enhance system scalability by optimizing data storage and exploring encryption schemes that are resilient to lossy compression. This will ensure that encrypted images do not occupy excessive storage while still allowing facial data to be decrypted even after image compression. Additionally, we will develop fine-grained access control that enables image owners to grant selective access to specific facial regions. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Initial** & **Revocation** & **Revoked** & **Remaining** & **Avg. Server** & **Avg. CSP** \\
**Authorized** & **Step** & **Users1** & **Authorized** & **Processing** & **Revocation** \\
**Users** & & & **Users2** & **Time (ms)** & **Time** \\ \hline
18 & 1 st & 5 & 13 & 15.7 \(\pm\) 8.79 & 5.77 \(\pm\) 0.52 \\  & 2 nd & 6 & 7 & 12.51 \(\pm\) 0.79 & 6.02 \(\pm\) 0.69 \\  & 3 rd & 7 & 0 & 12.58 \(\pm\) 1.35 & 6.01 \(\pm\) 0.82 \\
27 & 1 st & 8 & 19 & 13.77 \(\pm\) 2.13 & 7.19 \(\pm\) 2.11 \\  & 2 nd & 9 & 10 & 12.98 \(\pm\) 3.42 & 6.63 \(\pm\) 3.52 \\  & 3 rd & 10 & 0 & 12.89 \(\pm\) 2.09 & 6.45 \(\pm\) 1.92 \\
36 & 1 st & 11 & 25 & 12.27 \(\pm\) 0.9 & 5.8 \(\pm\) 0.59 \\  & 2 nd & 12 & 13 & 12.85 \(\pm\) 2.91 & 5.69 \(\pm\) 0.77 \\  & 3 rd & 13 & 0 & 11.95 \(\pm\) 0.72 & 5.62 \(\pm\) 0.62 \\ \hline \hline \end{tabular}  
* The number of revoked users has been verified to ensure that their access has been successfully removed. 2 The number of remaining authorized users has been validated to confirm their continued access to the face.  
\end{table} 
Table 8: Performance evaluation of revocation operations. These improvements will improve user control over facial data sharing, ensuring that image owners can grant access to specific facial data rather than revealing all faces to authorized users. Conceptualization, A.S. and S.H. ; methodology, A.S. and S.H. ; software, A.S.; validation, A.S.; formal analysis, A.S., S.H., Y.K. and Y.N. ; investigation, A.S., S.H., Y.K. and Y.N. ; resources, A.S. and Y.N. ; data curation, A.S.; writing--original draft preparation, A.S. and S.H. ; writing--review and editing, A.S., S.H., Y.K. and Y.N.