\documentstyle[12pt,twoside,alltt]{article}
\textwidth=6in
\oddsidemargin=0.25in
\evensidemargin=0.25in
\topmargin=-0.1in
\footskip=0.8in
\parindent=0.0cm
\parskip=0.3cm
\textheight=8.00in
\setcounter{tocdepth} {3}
\setcounter{secnumdepth} {2}
\sloppy

\newenvironment{proof}{\noindent{\bf Proof:}}{\qed\bigskip}
\newenvironment{proof_sketch}{\noindent{\bf Sketch of 
Proof}\hspace*{1em}}{\qed\bigskip}

\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{lemma}{Lemma}
\newtheorem{claim}{Claim}
\newtheorem{fact}{Fact}
\newtheorem{definition}{Definition}
\newtheorem{assumption}{Assumption}
\newtheorem{observation}{Observation}
\newtheorem{example}{Example}
\newcommand{\qed}{\rule{7pt}{7pt}}

\newcommand{\lecture}[4]{
\pagestyle{headings}
\thispagestyle{plain}
\newpage
\noindent
\begin{center}
\framebox{
\vbox{
\hbox to 5.75in { {\bf 6.857 Computer and Network Security
\hfill Fall Term, 1996}  }
\vspace{4mm}
\hbox to 5.75in { {\Large \hfill Lecture #1 : #2 \hfill} }
\vspace{2mm}
\hbox to 5.75in { {\it Lecturer: #3 \hfill Scribe: #4} }
}
}
\end{center}
\markboth{Lecture #1 : #2}{Lecture #1 : #2}
\vspace*{4mm}
}

\begin{document}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Lecture command takes 4 arguments:
%		ordinal number of the lecure
%		date of the lecure
%		lecturer
%		scribe---that is you
%
\lecture{3}{September 12th}{Ron Rivest}{Peter Sun} 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% For theorems, lemmas, definitions, remarks, etc. use commands
% \begin{theorem} .... \end{theorem} 
% \begin{definition} ... \end{definition} 
% \begin{proof} ... \end{proof}
% and so on ...
%
% If you want to insert figures in your notes do the following: 
% 1) Prepare your figures using your favourite graphic editor
% 	for example idraw or xfig
% 2) Save your pictures in PostScript form using the following convention
% 	notes-nn-fig-mm.ps where nn is the number of the lecture you 
% 	are scribing and mm is the sequential number of the picture in the 
% 	notes
% 3) Insert the following block in your LaTeX code in the place you 
% 	want to insert the figure BUT LEAVE IT AS A COMMENT (with the %
% 	at the beginning of the line) since it will not work on athena: 
%
% \begin{figure}[h]
% \begin{center}
% \mbox{\psfig{figure=notes-nn-fig-mm.ps}}
% \caption{A very nice picture.}
% \label{fig:mm}
% \end{center}
% \end{figure}
%
% 	of course the picture will not show up when you compile and 
% 	print your notes, but don't worry the TA will take care of it. 
% 4) When you mail the TA the LaTeX code mail him/her the PostScript
%	files for the figures as well 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Your notes start here!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section {Protecting Computer Systems}

Every weekend, one or two notebooks are stolen from the labs in 
Technology Square.  The prevent theft, computers can be secured 
by locking the machine to a heavy or bulky object (such as a desk), 
locking the media readers (making it difficult or impossible to
use), or locking the computer itself to prevent operation (such as a 
keyboard or a power supply lock).

\subsection {Protecting Physical Media}

Possible security leaks include:
\begin{itemize}
	\item {\bf Dumpster Diving:} Disposed documents and printouts 
may yield many secrets such as passwords and confidential information.
	\item {\bf Magnetic Storage Media:} Deleted information can 
often be undeleted.
\end{itemize}

Possible solutions to these attacks include:

\begin{itemize}
	\item {\bf Clearing:} Overwrite the media many times with 
random bits.  Writing to magnetic media can be thought of as spray 
painting a wall.  To cover up old information, you need to ``paint'' 
over it several times.
	\item {\bf Purging:} Using ultraviolet lights to destroy 
EEPROMs or using a strong magnet on magnetic storage.
	\item {\bf Destruction:} Burning paper documents, grinding 
off magnetic coating, melting tapes, etc.
\end{itemize}

The idea of protecting media is to build fences.  Physical protection
is never perfect; you want to build the barriers high enough so that
your attacker will choose an easier target.

\subsection{Protecting Software}

Another facet of media protection is against software piracy.  
Software companies such as Microsoft and Nintendo have often utilized
the following techniques:

\begin{itemize}
	\item {\bf Serial Number/Manual Text Check}
	\item {\bf CPU/Network Address Check}
	\item {\bf Harware Dongles:} A special hardware device that 
attaches to the serial port.  It contains circuitry or data that is 
needed to run the software.
	\item {\bf Holograms:} Special packaging that prevents foreign
duplicators from making ``offical looking'' copies.
	\item {\bf Watermarking:} Each software package has a unique 
feature or generates a unique output.

{\em example:} Postscript.
\end{itemize}

Often the most effective copy protection is no protection at all.  By 
lowering the price of the software or by providing excellent support 
services, many users are willing to buy their own copy of the 
software.

Defeated software protection mechanisms are often detected through 
increased support calls, decreased sales, and by finding anonymous
postings of binaries on web sites.

\subsection{Protecting Devices and Circuitry}

The category of devices and circuitry covers all of the electronic 
components not considered strictly a computer.  Examples of such
items include ATM machines, smart cards, electronic wallets, Nintendo 
security chips, etc.  There are two protection techniques: passive 
(preventative) and active (counter measures).

\subsubsection{Passive Protection Techniques}

\begin{itemize}
	\item {\bf Burying Circuitry in Epoxy:} Makes components hard 
to remove and study.
	\item {\bf Special Coating:} Make the circuitry packaging out
of specia materials.
	      
{\em example: } A layer of alumina, silicon bits, diamond 
dust, sodium, and binder coating encapsulates the chip making it hard 
to etch.  The sodium is reactive causing further damage when exposed.  
These coatings are expensive.
\end{itemize}

\subsubsection{Active Protection Techniques}

\begin{itemize}
	\item {\bf Self Destuct Device:} Destroys a device or 
circuitry because any useful funciton or information can be accessed 
or obtained.
	\item {\bf Sensors:} Wires, beams, radio waves, etc. that 
detect motion, heat, light, sound, and radiation generated by an 
attacker.  Alarms are usually triggered.
\end{itemize}

Possible security leaks for active techniques include:

\begin{itemize}
	\item {\bf Fast Attacks:} Enemy may destroy counter measures
before they are activated.  Examples include bombs and guns.
	\item {\bf Slow Attacks:} Techniques that carefully bypass the
counter measures.  For example, carefully drilling into an ATM.
	\item {\bf Power usage and timing:} By looking at other properties
of a system, functionality information may be detected.
\end{itemize}

\subsection{Electromagnetic Radiations}

Computers (in particular their monitors and their communications
lines) emit electromagnetic radiation.  It is possible for an attacker
to make use of such emissions in order to create privacy breaches.

Computer CRT signals can be picked up from distances of up to several
thousand feet with simple, cheap equipment.  Ordinary phone wires are
prone to both active attacks (using alligator clips and listening
to the signal) which can be detected or inductive attacks which are
harder to notice.  Fiber optic cables can be compromised by splicing 
a repeater, bending or nicking the wire, or placing the wire in 
high-refractive liquids and allowing the light to escape.

It is possible to shield a computer, but it is difficult and expensive
to do it well.  One possible solution to the CRT problems is to replace
conventional tubes with LCD screens.  {\sc Tempest} is the name of the 
U.S. Government program under which computer equipment is certified as 
not emitting detectable signals.  One approach is to surround circuits
with metal shielding.  Shielding the whole computer is difficult, since
the shield should enclose everything.  Some companies choose to shield
their entire facility.

{\em example:} Schwartau, p.138.

\section{Recommended Readings}

{\em Information Warfare} by Winn Schartaw

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Your notes end here!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\end{document}
----------
