2007-04-20
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1. How to study this weekend for the midterm:
   (1) Do as many problems from the textbook that you can from
       the sections we covered.  Most solutions are in the back
       of the book.
   (2) Do the practice midterm, which I'll hand out. 
       Note -- I haven't "tested" the practice midterm much; I will
       test the real one much more. 

2. Complete example of:
  I. Encoding a phrase in a number.
    (a) Base 27 (or can use other bases)
    (b) Discuss issue with padding.
  II. Setting up and sending a message using RSA
  III. Digitally signing a message.
       (a) Just sign by encrypting using (d, n).  
       (b) Then anybody can decrypt using (e, n) and hence verify that
           message is really from you, since only you know (d,n). 
       Very cool!
  
3. Discuss factoring n=p*q given phi(n), if time permits. 

4. Projects -- many of you have come up with some excellent
   ideas.  Good job.    If you're a junior and do one of the
   top projects, I will try to set you up with a faculty member
   to do a senior thesis in math next year, if you're interested.