This assignment has two goals: (a) experience with Diffie-Hellman key
exchange and AES and (b) deciding when your class presentation will
take place.
To these ends a protocol between you and me must be followed.
The steps of the protocol are as follows:
-
Choose a four digit prime p, a generator g
for the multiplicative group mod p and
a random number x between 2 and p-2 and send
p, g and
g x mod p
to me at dkrizanc at wesleyan.edu.
-
I will send you a message containing
b = g y mod p
for some randomly chosen y. You should compute
k = b x mod p.
-
We will now use k as a key for AES in order to send messages
concerning the presentation. Order the following five presentation
dates in order of preference, from most preferrable to least preferrable:
Tuesday, November 27, 9 am;
Thursday, November 29, 9 am;
Tuesday, December 4, 9 am;
Tuesday, December 4, 7 pm;
Thursday, December 6, 9 am.
Using the AES applet available at
http://aes.crockatt.com/ and the key k, encode
your preference list and send me the resulting ciphertext.
-
Once I receive and successfully decode all preference lists, I will
assign presentation times as fairly as possible and send your time to
you using the same key.
-
You should decode the presentation time and
send me a cleartext message with the presentation time and the title
for your presentation.
Some Notes:
-
You might find applets for primality testing and
modular exponentation useful:
http://www-fs.informatik.uni-tuebingen.de/~reinhard/krypto/English/english.html
.
-
In order to ensure a timely result, you must complete the first step of
the protocol by
November 13
and the third step of the protocol by
November 16. If either of these steps have not been completed by these
dates, I reserve the right to assign presentation times at my discretion.
The fifth step of the protocol should be completed by
November 20.
-
The earlier I receive your request, the better the chance it will be
honored.
