# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1353287512 0
# Node ID fb14a8e1b00ddebe6f892fe93df770c7201c7c7e
# Parent  e0f538ce04bb1f8858e9f60acea8fb72f7d8a8a3
added hw 7

diff -r e0f538ce04bb -r fb14a8e1b00d hw06.pdf
Binary file hw06.pdf has changed
diff -r e0f538ce04bb -r fb14a8e1b00d hw06.tex
--- a/hw06.tex	Tue Nov 13 21:07:21 2012 +0000
+++ b/hw06.tex	Mon Nov 19 01:11:52 2012 +0000
@@ -16,9 +16,7 @@
 where $P$ is a principal and $F$ a formula. Give two inference rules
 of access-control logic involving $\textit{says}$.
 
-\item
-The informal meaning of the formula $P\;\textit{controls}\;F$ is `$P$ is entitled
-to do $F$'. Give a definition for this formula in terms of $\textit{says}$. 
+\item (Removed) Was already used in HW 5
 
 \item 
 Assume an access control logic with security levels, say top secret ({\it TS}),
diff -r e0f538ce04bb -r fb14a8e1b00d hw07.pdf
Binary file hw07.pdf has changed
diff -r e0f538ce04bb -r fb14a8e1b00d hw07.tex
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hw07.tex	Mon Nov 19 01:11:52 2012 +0000
@@ -0,0 +1,40 @@
+\documentclass{article}
+\usepackage{charter}
+\usepackage{hyperref}
+\usepackage{amssymb}
+\usepackage{proof}
+
+\begin{document}
+
+\section*{Homework 7}
+
+\begin{enumerate}
+\item Suppose a judgement is of the form:
+\begin{center}
+$Alice\;\textit{says}\;S \wedge Bob\;\textit{says}\;S \vdash Bob\;\textit{says}\;S \wedge Alice\;\textit{says}\;S$
+\end{center}
+
+Assume you want to use the inference rule
+
+\begin{center}
+\mbox{\infer{\Gamma \vdash F_1 \wedge F_2}{\Gamma \vdash F_1 & \Gamma \vdash F_2}}
+\end{center}
+
+for constructing a proof of the judgement. What do the premises look like? 
+
+\item The informal meaning of the formula \mbox{$P\;\mapsto\;Q$} is `$P$ speaks for
+$Q$'. Give a definition for this formula in terms of $\textit{says}$.
+
+\item In Unix, what should be the general architecture of a network application that 
+processes potentially hostile data from the Internet? (Hint: Focus on the fact that in Unix
+you can give different privileges to processes.)
+
+\item Explain what are the differences between dictionary and brute forcing attacks  against  passwords.
+
+\end{enumerate}
+\end{document}
+
+%%% Local Variables: 
+%%% mode: latex
+%%% TeX-master: t
+%%% End: 
diff -r e0f538ce04bb -r fb14a8e1b00d slides07.pdf
Binary file slides07.pdf has changed