diff -r 98ae49ffc262 -r 62985f147c85 hws/hw06.tex
--- a/hws/hw06.tex	Tue Sep 26 12:03:24 2017 +0100
+++ b/hws/hw06.tex	Tue Sep 26 12:10:41 2017 +0100
@@ -1,37 +1,65 @@
 \documentclass{article}
 \usepackage{../style}
 
-
 \begin{document}
 
 \section*{Homework 6}
 
-\HEADER
+\begin{enumerate}
+\item What are good uses of anonymity services like Tor?
 
-\begin{enumerate}
-\item Explain briefly the purpose of the certification authority in
-  the public-private key encryption scheme.
+\item What is meant by the notion \emph{forward privacy}?
+
+\item What is a \emph{re-identification attack}?
 
-\item Explain briefly what is meant by a certification authority
-  becoming ``too big to fail'' when it has issued a large number 
-  of certificates.
+\item Imagine you have a completely `innocent' email message,
+      like birthday wishes to your grandmother. Why should you
+      still encrypt this message and your grandmother take the
+      effort to decrypt it? 
 
-\item In which situations does it make sense to install
-  invalid (self-signed) certificates?
+      (Hint: The answer has nothing to do with preserving the
+      privacy of your grandmother and nothing to do with
+      keeping her birthday wishes supersecret. Also nothing to
+      do with you and grandmother testing the latest
+      encryption technology, nor just for the sake of it.)
 
-
-%\item Zero-knowledge protocols depend on three main properties called
-%  completeness, soundness and zero-knowledge.  Explain what they mean?
-
-%\item Why do zero-knowledge protocols require an NP-problem as building
-%  block?
+\item One part of achieving privacy (but not the only one) is to
+  properly encrypt your conversations on the Internet.  But this is
+  fiercely resisted by some spy agencies.  These agencies (and some
+  politicians for that matter) argue that, for example, ISIL's
+  recruiters broadcast messages on, say, Twitter, and get people to
+  follow them. Then they move potential recruits to Twitter Direct
+  Messaging to evaluate if they are a legitimate recruit. If yes, they
+  move them to an encrypted mobile-messaging app. The spy agencies
+  argue that although they can follow the conversations on Twitter,
+  they ``go dark'' on the encrypted message app. To counter this
+  ``going-dark problem'', the spy agencies push for the implementation
+  of back-doors in iMessage and Facebook and Skype and everything else
+  UK or US-made, which they can use eavesdrop on conversations without
+  the conversants' knowledge or consent.\medskip
+   
+      What is the fallacy in the spy agencies going-dark argument?
+      (Hint: Think what would happen if the spy agencies and certain
+      politicians get their wish.)
+       
+\item DNA data is very sensitive and can easily violate the privacy of
+  (living) people. To get around this, two scientists from Denmark
+  proposed to create a \emph{necrogenomic database} which would record
+  the DNA data of all Danish citizens and residents at the time of
+  their \emph{death}. By matching these to information about illnesses
+  and ailments in life, helpful evidence could be gathered about the
+  genetic origins of diseases.  The idea is that the privacy of dead
+  people cannot be violated.
 
-%\item Why is it a good choice in a ZKP to flip a coin when requesting a 
-%  proof from the person who knows the secret?
+      What is the fallacy behind this reasoning?
 
-\item \POSTSCRIPT
-\end{enumerate}
+\item A few years ago a Google executive tried to allay worries about
+  Google pooring over all your emails on Gmail. He said something
+  along the lines: you are watched by an algorithm; this is like being
+  naked in front of your dog. What is wrong with this argument?
 
+\item \POSTSCRIPT  
+\end{enumerate} 
 \end{document}
 
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