Reversible Data Hiding For 3D Mesh Models In Encrypted Domains Research On Hiding Method

With the popularization and development of 3D printing technology and cloud computing,the data security and privacy of 3D models are getting more and more attention,and it is important to study the lossless recovery of models and the hiding method of storing massive data.Reversible data hiding technique provides an effective solution for it.In this paper,we use the most common triangular surface sheet form grid model as the research vehicle,propose two reversible data hiding algorithms for 3D grid models to address the problems of embedding rate and recovery quality of existing reversible data hiding algorithms,and build a visual 3D model digital watermarking system.The main research work includes:(1)A reversible data hiding algorithm for 3D models optimized for vertex strategies is proposed.Firstly,the vertices of the grid model are divided,a new set of centers of gravity is generated in the full neighborhood,the MSBs of all vertex sets are predicted according to an improved prediction strategy to determine the maximum embedding bits,secondly,a smooth recovery model is obtained by applying the Laplace operator at the vertices at the receiving end,and finally,the mean curvature is visualized and analyzed.To prove the effectiveness of the algorithm,the experiments are selected to compare the embedding rate,SNR and the recovery model of different sizes of grid models with other traditional algorithms.The results show that the method in this paper not only improves the embedding rate,but also effectively removes the noise while retaining the local detail features of the recovered model,which improves the quality and visual effect of the model recovery and further achieves the purpose of data privacy and security.(2)A reversible data hiding algorithm based on homomorphic encryption is proposed.The additional information that needs to be embedded is first applied to the cryptographic construction,and no modification of the model data is required to improve the security of the algorithm in the cloud.The algorithm first calculates the positive integer coordinates of the vertices of the 3D model,then uses the Dijkstra algorithm to find the shortest distance between all the vertices,ensures that the vertices do not overlap according to the divided blocks,then performs homomorphic encryption on the vertices in each block to get the marked encrypted model,and finally the receiver uses the homomorphic encryption feature to extract the data of its vertex coordinates according to whether it needs to extract the information or get the recovered model and recovery.It is proved that the algorithm is able to protect and store the 3D model securely,and it is also resistant to various attacks,especially translation and scaling attacks.(3)The visualized 3D model digital watermarking system is designed and implemented.The main functions of the system include 3D model input/output module,3D model display interaction module,semi-fragile watermarking algorithm based module,and smooth algorithm module based on Laplace operator.In this thesis,two reversible data hiding algorithms are proposed to improve the data embedding ability and model recovery quality,and to achieve visualization and analysis by color rendering model.The built visualized 3D model digital watermarking system provides a solution for the privacy protection of 3D models and has certain promotion value.