The growing use of 3D objects in applications such as augmented and virtual reality and computer-aided design poses serious challenges in terms of compression and security, particularly during transmission, storage in the cloud, and deployment in virtual environments such as the Metaverse. 3D crypto-compression, which integrates encryption and compression, provides an efficient solution, particularly joint compression and encryption methods, which ensure data confidentiality and storage efficiency while maintaining format compliance. In this article, we present a new and efficient method of selective crypto-compression using the Draco 3D compression format. Our approach applies selective encryption just after vertex quantization, using Advanced Encryption Standard in Cipher FeedBack mode to preserve random access, and decorrelate vertex positions. We further propose an adaptive selective encryption strategy that dynamically adjusts selective encryption parameters according to the desired visual security level. In addition, we introduce an edge length distribution analysis to evaluate the statistical security of the 3D object crypto-compression method we propose. Experimental results presented on a large database demonstrate that our method achieves an optimal tradeoff between compression efficiency and security, ensuring format compliance.

The widespread use of 3D objects in many fields poses new challenges for their secure transmission, storage and visualization. While selective encryption methods allow format compliance and enable adjustable security by selectively encrypting 3D geometry, they produce visible noise and disrupt geometric coherence which reduces compression efficiency. In this paper, we propose a reversible deformation method for 3D object protection that breaks with state-of-the-art 3D security approaches by offering more natural and visually coherent protection. The deformation is applied directly to the geometry, controlled by a secret key, and can be adjusted to achieve the desired level of visual security. Experimental results presented on a large database demonstrate that our method offers protection comparable to selective encryption, while providing significantly greater resilience to reconstruction attacks such as Laplacian smoothing, particularly at low security levels where selective encryption is more vulnerable. This work introduces a new direction for format-compliant 3D object protection, designed for secure visualization in untrusted environments.

In our present society, 3D objects play an increasingly important role in many different domains, especially with the development of meta environments. Many applications demand large 3D objects, which makes their compression a requirement. Meanwhile, 3D objects are also exposed to various security problems during online storage and transmission. Consequently, security aspects such as copyright and authentication are essential for 3D objects. In this paper, we propose a simultaneous 3D object watermarking and compression method based on Draco. A watermarking step is integrated within Draco, Google’s 3D compression method, which is rapidly being universally adopted as standard. The proposed method enables a large bit embedding rate, which can be used for copyright information. The proposed method is also, to the best of our knowledge, the first watermarking method for 3D objects compressed with Draco.

With the increasing popularity of 3D objects in industry and everyday life, 3D object security has become essential. While there exists methods for 3D selective encryption, where a clear 3D object is encrypted so that the result has the desired level of visual security, to our knowledge, no method exists for decrypting encrypted 3D objects hierarchically. In this paper, we are the first to propose propose a method which allows us to hierarchically decrypt an encrypted 3D object according to a generated ring of keys. This ring consists of a set of keys that allow a stronger or weaker decryption of the encrypted 3D object. Each hierarchically decrypted 3D object has a different visual security level, where the 3D object is more or less visually accessible. Based on a master key, these hierarchical keys are generated using our method during the encryption process. Our method is essential when it comes to preventing trade secrets from being leaked from within a company or by exterior attackers. It is also ecologically friendly and more secure than traditional selective encryption methods.

For over a decade, 3D objects are an increasingly popular form of media. It has become necessary and urgent to secure them during their transmission or archiving. In this article, we propose a new method to obtain a watermarked 3D object from high-capacity data hiding in the encrypted domain. Based on the homomorphic properties of the Paillier cryptosystem, our proposed method allows us to embed several secret messages in the encrypted domain with a high-capacity. These messages can be extracted in the plain-text domain after the 3D object decryption. To the best of our knowledge, we are the first to propose a data hiding method in the encrypted domain where the high-capacity watermark is conserved in the plain-text domain after the 3D object is decrypted. The encryption and the data hiding in the encrypted domain are format compliant and without size expansion, despite the use of the Paillier cryptosystem. Each time a new message is embedded in the encrypted domain, flags are added in order to indicate which blocks are still available for the embedding of additional messages. After the decryption of a watermarked encrypted 3D object, our method produces a watermarked 3D object which is visually very similar to the original 3D object. From the decrypted watermarked 3D object, we can then extract all the embedded messages directly in the plain-text domain, without the need for an auxiliary file. Moreover, large keys are used, rending our method secure for real-life applications.

3D objects play an essential role in industry and everyday life. They are often stored on the cloud and transferred many times during their existence, and so 3D object security is essential. To the best of our knowledge, no method exists to hierarchically decrypt fully encrypted 3D objects. In this paper, we propose a new method to hierarchically decrypt a 3D object so that the visual accessibility of the resulting 3D object depends on the user's rights. For that, it is based on the hierarchy of the key used during the decryption. The decryption key is selected from a ring of hierarchical keys which are generated and distributed to the respective users during the encryption process. The proposed method is eco-friendly as a single 3D object is fully encrypted (confidential level) and available to several users with different rights. Experimental results show that our method is efficient and can be used for real applications.

Today, 3D objects are an increasingly popular form of media. It has become necessary to secure them during their transmission or archiving. In this paper, we propose a two tier reversible data hiding method for 3D objects in the encrypted domain. Based on the homomorphic properties of the Paillier cryptosystem, our proposed method embeds a first tier message in the encrypted domain which can be extracted in either the encrypted domain or the clear domain. Indeed, our method produces a marked 3D object which is visually very similar to the original object. It seeks to be format compliant and to preserve the original size of the data, without the need for an auxiliary file. Moreover, large keys are used, rending our method secure for real life applications.

New issues have arisen in the creation of 3D objects linked to collaboration in 3D workflows. In this kind of usage it may be necessary to allow access and to share a lower quality file of a 3D object for some collaborators. In this paper, we present a Format-Compliant Selective Secret 3D Object Sharing (FCSS3DOS) scheme, which visually protects the content using geometrical distortions by selectively sharing bits of a 3D object's geometry using Shamir's Secret Sharing scheme. The degradation level D is selected before the sharing process and determines how much geometrical distortions are induced into n generated shared 3D objects which are given to n participants. When at least k or more participants agree to combine their own shared 3D objects, then the secret 3D object can be recovered without distortion. The value of k can vary between 2 and n. In experimental results, we ana-lyze the degradation level D that influences the geometrical distortions induced into shared 3D objects.

This paper presents a new method of secret three-dimensional object sharing (S3DOS), which allows sharing of three-dimensional (3-D) objects, while preserving its file format by selectively encrypting a 3-D object in order to sufficiently protect the visual nature of the content. This scheme, named format-compliant selective (k, n) S3DOS, modifies selected bits of the vertices of a 3-D object to protect the visual content by inducing geometrical distortions. These distortions are controlled thanks to the application of a degradation level at the beginning of the sharing process. To reconstruct the secret 3-D object, at least k shared 3-D objects among n have to be combined in order to remove the geometrical distortions and recover the exact original 3-D object. Experimental results are presented and evaluated to showcase the feasibility of the proposed scheme.

Visual Secret Sharing (VSS) is a type of cryptographic method used to secure digital media such as images by splitting it into n shares. Then, with k or more shares, the secret media can be reconstructed. Without the required number of shares, they are totally useless individually. The purpose of secret sharing methods is to reinforce the cryptographic approach from different points of failure as a single information-container. Instead of Lagrange's interpolation employed by classical methods, an approach based on linear equations and coding theory resolves the classic problems of VSS methods like pixel expansion and information losses at recovery time. In this paper, we propose an efficient (2, n) secret image sharing scheme without loss of information and size increase of shares, with n ≤ 7 based on linear equations encoded into eight bits to encode separately pixels and permutations to maintain high entropy in shares.

3D meshes are widely used today in very different domains for example; game, medical diagnostic, CAD (computed aided design) or more recently 3-D printing. In this paper, we provide a new data hiding method that has a huge capacity, cp = 3c(n - 1), where n is the vertex number of the mesh and c is an integer. The proposed method consists to compute a Hamiltonian path along the mesh as synchronization. At each step of path building, 3c bits are embedded. The embedding is designed to be a distance relation between a vertex and its father in the path. Moreover, the method uses static arithmetic coding to embed message information. We analyzed the proposed method by inserting RGB images in 3D meshes.

Efficient data synchronization for 3D mesh models is a new major challenge. 3D models are also now being used to an increasing extent and with current network technology, 3D model compression, visualization and protection demand increases. However, there is still no perfect method to achieve this data synchronization while being blind and robust against various attacks. We propose a blind method based on a Hamiltonian path to synchronize vertex clouds, and particularly on 3D meshes. We experimentally show that it is fast and robust against Gaussian noise. This novel approach can generate better results than mesh-based methods because it does not use vertex connectivity.