Presentation on theme: "BMP Hide ‘n’ Seek What is BMP Hide ‘n’ Seek ? –It’s a tool that lets you hide text messages in BMP files without much visible change in the picture. –Change."— Presentation transcript:
BMP Hide ‘n’ Seek What is BMP Hide ‘n’ Seek ? –It’s a tool that lets you hide text messages in BMP files without much visible change in the picture. –Change in picture is difficult to be identified with naked eye. –The quality of picture depends upon the number of characters to be stored and the original bmp file
Basic Principle Used Steganography Principle : Art of hiding one message in another message Here it’s the art of hiding text in image
BMP File Format Header Info - First 56 bytes Picture Info - From 57 th byte - EOF –After the 57 th byte the data can be manipulated in order to hide the text
Let’s See An Example The raw data in a BMP file may look like this FA EC D4 F5 E3 E5 E7 45 F2 –FA,EC,D4….. corresponds to the picture information for a particular pixel –The first character in the hex code FA EC D4 F5 E3 … contains more information when compared to the 2 nd character. Therefore the 2 nd character is always changed to hide the text
E.g. If You want to hide the Character ‘A’ Hex Code For ‘A’ = 41 FA EC D4 F5 E3 E5 E7 45 F2 The New Hex Code Will Look Like F4 E1 D4 F5 E3 E5 E7 45 F2 This Code is Stored in the File replacing the original code 41
Hiding Text The original BMP file is opened and then copied to another file specified by the user The text to be hidden is converted to it’s ASCII value and then to it’s hex code Using the Principle explained above the old hex codes are read and changed depending on the text hex codes are stored The hex codes should only be changed from the 57 th byte or greater.
Use Of Secret Key Password ASCII Value of Password Starting Byte Location SEED For RND During retrieving data only if the password is right, will the starting position be right The Secret Key is used to identify the starting location.
Retrieving Hidden Text Depending upon the password the starting position is identified From the starting position every 2 nd character is read from every byte This is then converted Hex Code ASCII Values Text
E.g. of Retrieving Hidden Text F4 E1 D4 F5 E3 E5 E7 45 F A Hex Code ASCII Value Hidden Character