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# 資訊安全期末 Paper 報告 - PowerPoint PPT Presentation

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### 資訊安全期末Paper報告

Data Hiding on 3D Triangle Meshes

François Cayre and Benoît Macq, Senior Member, IEEE

89321018 藺心皓

1.Introduction
• 近年來由於電腦硬體的發達，間接促成3D技術的普及，因此有人開始將3D圖形的特性應用到Steganography之中。
• TSPS – Triangle Strip Peeling Sequence

1.Introduction (Cont.)
• 因此本篇paper主要提出一種簡易且提高安全性的TSPS修改版
2.Background
• cover- media : 用來遮掩plaintext的東西，在本篇中即為 Triangle-Meshes
• Payload : 其實就是 plaintext
• 本篇paper所使用的加密方法 : substitutive

Blind scheme in the spatial domain.

2.Background(cont.)

3. PRESENTATION OF THE PROPOSED ALGORITHM
• TSPS basic idea :

3. PRESENTATION OF THE PROPOSED ALGORITHM　(cont.)
• 基本的演算法，包含兩個步驟：
• 1. 利用Secret Key 找出用來掩蓋payload的Triangle mesh
• 2. 將payload 與 mesh結合，此步驟稱為

macro embedding procedure (MEP)

3. PRESENTATION OF THE PROPOSED ALGORITHM　(cont.)
• Part1 : mesh strip的挑選取決於secret key
3. PRESENTATION OF THE PROPOSED ALGORITHM　(cont.)
• Part2.(MEP)

Define :

P 為在空間中垂直於line_AB的平面

4. Binary MEP

4. Binary MEP 　(cont.)

“入k” : C(原本Triangle兩個exit edge所夾的point) 到 P的距離

4. Binary MEP 　(cont.)

5.Moving on the Mesh

1. Avoiding Peeling

2. Admissibility and Upper Bound for Capacity

Data store upper bound = number of points inside the cover mesh

5.Moving on the Mesh(cont.)
• Topological Boundaries: Initial and the Final Cells

Initial Cells : 兩種方法，一是選擇具有某些特性的三角形(面積max or min, etc.)，另一方法則是由Secret key決定。

Final Cells : 由secret key決定 (key的長度 = payload data 的長度)

5.Moving on the Mesh(cont.)
• Security

Attacker需要解決的兩個首要的問題：

• Find the initial Cells
• Find the path over the meshes
6. RESULTS AND FUTURE IMPROVEMENTS

Coding speed

&