A Study on Digital User Authentication Using New Robust Watermarking Based on Visual Cryptography

• Main Authors: Tung-Lin Tsai, 蔡東霖
• Other Authors: Rong-Chin Lo
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/5rvpbm

碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 95 === In this thesis, a new construction algorithm of watermarking based on visual cryptography is proposed. In the past years, there are many watermarking schemes addressed, these schemes most include spatial-domain and transform-domain. Spatial-domain is easy to access and low computing load but robust not enough. Transform-domain has good robust application, but the computing load also high the former. Visual cryptography is a new cryptography idea for image encryption, which was addressed from M. Naor and A. Shamir in 1994 [1]. After utilizing the visual cryptography to encrypt the secret image, we can get two shares. The persons who decode are unable via the single share image to get any information of the secret image. And the method to decipher is quite simple, do not need complicated computer operation; So long as one share (share1) will be stacked in second share (share2) another one, namely can see secret image. We will use visual cryptography scheme (VCS) to encrypt watermark into two shares. One is embedded into protected image as authentication; another one is regarded as and deciphered the necessary key. Among experiments, we try to use two-tone, gray-level and color watermarks to embed into gray-level and color images, and simulation is in case of receiving various kinds of attacks. The watermark is retrieved then distinguished high by the human visual system; we can prove one thing that endures various kinds of attacks strongly.