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.

Social network development raises many issues relating to privacy protection for images. In particular, multi-party privacy protection conflicts can take place when an image is published by only one of its owners. Indeed, privacy settings applied to this image are those of its owner and people on the image are not involved in the process. In this paper, we propose a new hierarchical secret image sharing scheme for social networks in order to answer this problem. Based on the disjunctive multi-level approach of Belenkiy applied to images, this solution ensures user privacy, as shown by our obtained experimental results.

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.

3D steganography is used in order to embed or hide information into 3D objects without causing visible or machine detectable modifications. In this paper we rethink about a high capacity 3D steganography based on the Hamiltonian path quantization, and increase its resistance to steganalysis. We analyze the parameters that may influence the distortion of a 3D shape as well as the resistance of the steganography to 3D steganalysis. According to the experimental results, the proposed high capacity 3D steganographic method has an increased resistance to steganalysis.

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.