A new method of steganography : embedding information on metal surface

Abstract

Steganography, literally means 'Covered Writing', IS intended to prevent the

detection of hidden messages being read by a third party. Numerous methods to

conceal messages are being used from ancient times which include wax tablets used

by ancient Greek to invisible inks used by French Resistance in World War 2,

microdots, digital signatures and various digital watermarking methods.

In this dissertation, a new method of Steganography is introduced where the

information is embedded on the metal surface. Micro milling and EDM machining

techniques are used to create feed marks on the surface of the metal. The feed marks

are manipulated by different parameters of machining like feed rate in milling and

voltage and feed rate in EDM to create different patterns. Both these machining is

done on the micro machine tool, Mikrotool DT-110.

Different sets of patterns can be given different meaning and thus secret messages

can be written on the metal surface. In this project, the information is written in

binary code and thus two kinds of patterns are created. One kind is given the value

'1' and the other '0'. The machining is done either throughout a line on the surface

as one dimensional or on the entire surface composed of different single lines as

two dimensional coding.

In steganography, the messages should reach the intended person correctly and

flawlessly. So a method of decoding is also introduced in this project. A program

written in the Matlab decodes the information which is read by a profilograph,

Talyscan 150. The data output from the profilograph is read by the matlab program

and is then filtered using the Gaussian filter. The filtered data is then used to

calculate the pitch and hence the feed of machining and the original pattern. The

hidden digits of the different patterns are then combined and read to get the original

message.

Hence, a new method of Steganography is successfully introduced in this project.

This method can be used in various applications including authentication of the

originality of luxury goods and conveyance of secret messages for military and

other confidential applications.