# Encryption of 3D or Higher-Dimensional Images: A Review
## 4 Literature Review
[47] proposed a privacy protection scheme for 3D point cloud classification based on a chaotic optical encryption scheme. Mutually coupled spin-polarized vertical-cavity surface-emitting lasers (MC-SPVCSELs) subjected to dual optical feedback (DOF) were used to generate optical chaos from the permutation and diffusion of point clouds. In addition, they performed security analysis by analyzing the geometric features of the 3D point cloud. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Paper** & **RQ1** & **RQ2** & **RQ3** & **RQ4** & **RQ5** \\ \hline \multirow{3}{*}{[33]} & \multirow{3}{*}{Frequency} & \multicolumn{2}{c}{Steerable} & \multicolumn{2}{c}{Statistical analysis (analysis of the histogram of the original and encrypted} & \multirow{3}{*}{-} \\  & & \multicolumn{2}{c}{Cosine Number} & \multicolumn{2}{c}{Total} & \\  & & \multicolumn{2}{c}{Transform} & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\ \hline \multirow{3}{*}{[34]} & \multirow{3}{*}{Spatial} & \multirow{3}{*}{-} & \multirow{3}{*}{Partial} & \multicolumn{2}{c}{Statistical analysis (histogram analysis of the original and encrypted image,} \\  & & & & & \\ \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Paper** & **RQ1** & **RQ2** & **RQ3** & **RQ4** & **ROS5** \\ \hline
[40] & Frequency & \
\begin{tabular}{c} Fourier \\ Transform \\ \end{tabular} & Total &
\begin{tabular}{c} Histogram analysis; horizontal, vertical, and diagonal correlation coefficient analysis; \\ information loss verification in decryption process: root mean square error (RMSE) and \\ PSNR resistance to differential attack analysis (NPCR and UACI) \\ \end{tabular} & - \\ \hline
[41] & Spatial & - & Partial & \
\begin{tabular}{c} Statistical analysis (histogram analysis and entropy analysis); key space analysis; time \\ required to encrypt the image; resisting differential attack analysis \\ \end{tabular} &
\begin{tabular}{c} DNA sequences and \\ chaotic systems \\ \end{tabular} \\ \hline
[43] & Spatial & - & Total &
\begin{tabular}{c} Robustness of the proposed approach against potential statistical attacks; size of the key \\ space of the proposed cipher to demonstrate its resistance against brute force attacks; \\ sensitivity of the proposed method to key and plaintext perturbations, histogram \\ analysis; SBM; number of belief change rate (NPCR), and unified average changing \\ intensity (UACI) randomness tests to evaluate the strength of the proposed method \\ against differential attacks \\ \end{tabular} & Logistic and Gauss-circle maps \\ \hline
[44] & Spatial & - & Total & \
\begin{tabular}{c} Statistical analysis (histogram analysis; horizontal, vertical, and diagonal correlation of \\ neighboring pixels analysis; and entropy analysis); plaintext sensitivity analysis (NPCR) \\ and UACI; key space and sensitivity analysis; anti-chosen plaintext attack \\ \end{tabular} &
\begin{tabular}{c} Coupled chaotic \\ systems (PWLCM + \\ Duffing Map) \\ \end{tabular} \\ \hline
[45] & Spatial & - & Partial &
\begin{tabular}{c} Key space, correlation coefficient; encryption speed; PSNR; and SBM \\ \end{tabular} & - \\ \hline
[46] & Spatial & - & Partial &
\begin{tabular}{c} Key space analysis; key sensitivity analysis; correlation coefficient analysis; and \\ processing time \\ \end{tabular} & - \\ \hline
[47] & Spatial & - & Partial & \
\begin{tabular}{c} Critical chaos \\ generated by \\ mutually coupled \\ spin-polarized \\ vertical-cavity \\ surface-emitting \\ lasers \\ (MC-SPVCSELs) \\ subject to double \\ optical feedback \\ (DOF) \\ \end{tabular} & - & Partial &
\begin{tabular}{c} Critical chaos \\ generated by \\ mutually coupled \\ spin-polarized \\ vertical-cavity \\ surface-emitting \\ lasers \\ (MC-SPVCSELs) \\ subject to double \\ optical feedback \\ (DOF) \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._