Showing papers by "Wen-Hsiang Tsai published in 2008"

Secret Communication through Web Pages Using Special Space Codes in HTML Files

Abstract: A secret communication method via web pages by embedding special space codes in HTML text to encode message bits in triplets is proposed. The codes, replacing the ASCII space code 20, appear as white spaces as well, creating a steganographic effect. Such codes are found by a systematic investigation of all the coding systems applicable in the HTML. Message hiding and recovery processes are also proposed. The character string of each message, before being embedded, is randomized with a secret key to enhance the security against illegal intercept and extraction. The embedded message is non-destructible unless the web page server is intruded. Experimental results show the feasibility of the proposed method.

Data Hiding in Emails and Applications Using Unused ASCII Control Codes

Abstract: A new technique for hiding data in emails via Outlook Express and IE is proposed. Secret data are encoded by special ASCII control codes and embedded into cover emails by inserting the data into email text line ends. These special codes were found by systematically testing all the ASCII codes of various email server software systems and standards. The codes are invisible to the user when displayed, achieving the effect of steganography. The proposed data encoding technique is a combination of five coding rules. The inserted codes do not change the meaning of the sentences in the cover email, neither cause any noticeable difference to the reader. Furthermore, hidden data can be completely extracted from a stego-email to recover the original email text. Also, two applications of the proposed data hiding technique, namely covert communication via emails and authentication of emails, are described. In the first application, security is enhanced by the use of a secret key, and in the second, an authentication signal is generated from the cover email for email fidelity checking. Good experimental results show the feasibility of the proposed method. Keyword: data hiding, ASCII control codes, email, secret data, covert communication, email authentication.

A Robust and Accurate Calibration Method by Computer Vision Techniques for Coordinate Transformation between Display Screens and Their Images

Abstract: A robust and accurate calibration method for coordinate transformation between display screens and their images is proposed. The images of three specially designed calibration patterns, which are a white rectangle, a black rectangle, and a dot matrix, are captured and processed sequentially to assist achieving robust extraction of relevant fea- tures from the calibration pattern images, especially the border features in the image of the display screen. Image analysis techniques of deformable template matching, local thresholding, and inverse distance-weighted interpolation are integrated to perform fea- ture extraction and coordinate transformation to complete the calibration work. Good performance of the proposed method is demonstrated by comparing the experimental results of the method with those of a well-known calibration method.