NUI Galway – UL Alliance First Annual ENGINEERING AND - ARAN ...

1. Introduction
Steganography techniques in the AutoCAD environment
This thesis will be incorporating several different aspects
within the IT domain.
Steganography is defined as the art and science of writing
hidden messages in such a way that no one, apart from the
sender and intended recipient, suspects the existence of the
message, a form of security through obscurity.
Research into security keys and methods of encrypting
information is also involved in my research.
AutoCAD is a CAD (Computer Aided Design or Computer
Aided Drafting) software application for 2D and 3D design
and drafting. I became familiar with the AutoCAD
environment during my studies in Civil Engineering and
decided that it would be interesting to research into combining
the AutoCAD environment with Steganography.
2. Aim
The aim of this thesis is to investigate different methods of
Steganography within the AutoCAD environment using either
different tools or features within AutoCAD.
The 2010 version of AutoCAD is being used for testing for
this thesis. This version contains many improvements over
early versions of the application and has a 3D model space
which allows for more scope when researching methods of
information hiding.
It is hoped to develop several methods of message hiding.
These methods will each differ in complexity, size of message
that can be transmitted, ease of retrieval, etc.
3. Method
The following techniques were used in the development and
research into message hiding:
Hatch patterns – AutoCAD has a feature which allows users to
create their own custom hatch pattern. The hatch feature is
used to fill a certain area within the drawing with a particular
pattern. This is done so that materials/areas can be easily
identified within a drawing if they are given their own unique
pattern. With a custom pattern the user can generate what
seems to be just a complex pattern within a drawing but when
the intended 3rd party overlays this pattern with their „private
key‟ (custom pattern to decipher the message) then the
message is revealed.
Layers – layers within AutoCAD are similar to font types
within Microsoft Word. When a line is assigned to a particular
layer then it can be manipulated in different ways such as
„turning off‟ that layer would make all objects that were part
of the layer disappear. Using the layers feature as a method of
message hiding, a drawing is sent which contains an
David Kilgarriff and Conn Mulvihill
College of Engineering and Informatics
d.kilgarriff1@nuigalway.ie
156
incomplete floor plan of a house. This plan is generated with a
public key, the message is then decrypted using the intended
party‟s private key which places an overlay on the floor plan
thus revealing the message.
3D viewpoint – Within the 3D environment, a message is
written using an array of points. A message on a piece of
paper could be constructed using the X & Y axis. For this
method, the Z-axis is also used and pseudo-random values
between two limits are used for each point. This means that to
a normal observer there would seem to be a clutter of points
within the drawing with no real purpose, however, to the
intended 3rd party the message can be read by observing the
drawing at a certain point within 3d space and viewing the
drawing at a particular angle so that the pseudo-random z-axis
values do not impact on the message being conveyed.
Autocad drawing showing a crater made from an array of
3D points.
Autocad drawing showing a 3D model of a single room.
4. Conclusion
This paper details the design, methodology and advantages of
each method of hiding. It also details the development of a
small scale automated method of using the 3D viewport of
hiding which could be used to assist with copywriting
drawings or using the AutoCAD environment as a method of
transfer of a simple message between parties.
5. References
[1] Rafael C. Gonzalez & Richard E. Woods, “Digital Image
Processing “
[2] John C. Russ & J. Christian Russ, “Introduction to image
processing and Analysis”.