PHP Classes

Packages of Chao-Chyuan Shih

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Picture of Chao-Chyuan Shih
Name: Chao-Chyuan Shih <contact>
Classes: 2
Country: United States United States
Age: 73
All time rank: 73599 in United States United States
Week rank: 195 Up19 in United States United States Up
All time users: 4153
Week users: 0
Innovation award
Innovation award
Nominee: 2x
 
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  Files folder image BmpCrypt  
PHP Programming Innovation award nominee
April 2005
Number 3


Prize: One book of choice by SAMS
Encrypt and decrypt data hidden in bitmap image
BmpCrypt is a class that uses the steganography technique to hide encrypted data within a bitmap image (.BMP).

This class can hide the data very well in 24 or 32 bit RGB images.

The class could be used to hide the data in indexed color images, for instance of 256 colors, but that would require adding a few functions to deal with the modifications to the color palette.

This class implements 4 levels of bit stream encoding. Each level uses an increasing number of bits per each byte in the RGB pixel table. Therefore, the higher level of encoding will hold more bytes of data in the bitmap image.

The class comes with a Web base example that shows how to decrypt an encrypted JPEG out of a BMP file and displays the output image.

There is also an example script that shows how to use the class to encrypt and decrupt data from the command line.
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  Files folder image TxtCrypt  
PHP Programming Innovation award nominee
April 2005
Number 5
Encrypt a file and hide it in a regular text file
This class can encrypt a file and insert the encrypted data into a regular text file in such way that it does not change the way the text file appears.

The encrypt algorithm is simple but it can be replaced by another more robust algorithm.

To hide the encrypted data within a text file without changing how it appears, the data is compressed, encrypted, and converted to bit stream. The bit stream is then converted to tab (0x09) and space (0x20) characters , replacing the '1's and '0's of the bit stream. The resulting tab and space character strings is then added to the end of the carrier file.

The original carrier file size is also recorded as a converted bit stream in the end of the output file. This additional piece of information is used to extract the hidden file by the class decrypt function.
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