After the pictures of the
Three pictures of the Admiralty: The
Admiralty Admiralty Admiralty Recall that Room 40 of the
Admiralty was were the British cryptologists worked until their move to
Pictures of our tour of Bletchley Park: Bletchley station Bletchley stationBletchley
station Bletchley station The entrance to Bletchley Park The Mansion The
Mansion Station X (the wireless station)
is located in the turret. The Mansion
; the parking lot was the site of Hut 2. Churchill's window Alan Turing's hideaway and
Pictures of our tour of the
The Museum's Enigma display: Enigma display
Enigma display Enigma display Enigma display Enigma display Enigma display Enigma display Enigma display A commercial Enigma A Japanese Enigma
An Engima machine: Closed Enigma Closed Enigma Closed Enigma Open Enigma The Enigma plugboard
Engima rotors: An Enigma rotor An Enigma rotor The interior of an Enigma rotor A box of rotors Three rotors ready to be installed
The Museum's USN bombe: Bombe Bombe Bombe Bombe Bombe Bombe
The German Sturgeon machine: Sturgeon Sturgeon
A piece of the Japanese PURPLE machine and the PURPLE analog constructed by US codebreakers.
SIGSALY protected US communications. In particular, it protected communications between Roosevelt and Churchill. The SIGSALY display The SIGSALY display The SIGSALY turntables
The US-Russian Hotline
A Kryha device: Kryha Kryha Kryha
Various cipher devices from the Museum's display: Cipher devices Cipher devices Cipher devices Cipher devices Cipher devices Cipher devices
Here is a copy of the syllabus for
the 2002/2003 course in
Syllabus
Here is a copy of the day-by-day
schedule for the 2002/2003 class in
Day-by-day schedule for 2002/2003 class
Here are some notes that we were used
for the 2002/2003
Introduction to cryptology
Frequencies and patterns in English
Random alphabet ciphers
Keyword ciphers
Caesar ciphers
Cryptography of the Vigenere
cipher
Cryptanalysis of the Vigenere
cipher
One-time pads
Transposition ciphers
Playfair cipher
ADFGVX cipher
The Enigma machine
This was optional material:
The Friedman attack
Timeline of communication changes
Bibliography
For students who did the course for upper-division credit, this was the assignment in lieu of the paper on privacy:
Read the Hill cipher and do exercises 2, 3, and 9 and send them to me.
Read An introduction to public-key cryptology
Read Knapsack cryptosystem and do exercises 1 and 2 and send them to me.
Read RSA cryptosystem and do exercises 2, 3, and 5
and send them to me.
This was the final project:
1. This message has been enciphered with a Vigenere cipher. The Friedman test results provide evidence of that: the index of coincidence is 0.0408 (which suggests that the cipher is polyalphabetic) and the estimated length of the keyword is 9.4855. Here are the frequencies of individual letters and of the trigraphs . Cryptanalyze the message. Try to determine the keyword. You need not decipher the entire message, but do at least one fourth of it.
2. This message has been enciphered with a (full rectangle) transposition cipher. The Friedman test results are: the index of coincidence is 0.0749 (which suggest that the cipher is monoalphabetic) and the estimated length of the keyword (which is useless information for this exercise) is 0.7327. Here are the frequencies of individual letters (notice that these frequencies are similar to what we expect for plaintext) and of the trigraphs . Cryptanalyze the message.
3. Here is an enciphered message . The Friedman test results are: the index of coincidence is 0.0671 and the estimated length of the keyword is 0.9283. Here are the frequencies of individual letters and of the trigraphs . What method of encipherment do you think was used? Explain why you think that was the method that was used. Try to cryptanalyze the message. Explain how you attacked the ciphertext.
4. Here is an enciphered message . The Friedman test results are: the index of coincidence is 0.0649 and the estimated length of the keyword is 1.0025. Here are the frequencies of individual letters and of the trigraphs . What method of encipherment do you think was used? Explain why you think that was the method that was used. Try to cryptanalyze the message. Explain how you attacked the ciphertext.
5. Here is an enciphered message . The Friedman test results are: the index of coincidence is 0.0496 and the estimated length of the keyword is 2.3177. Here are the frequencies of individual letters and of the trigraphs . What method of encipherment do you think was used? Explain why you think that was the method that was used. Try to cryptanalyze the message. Explain how you attacked the ciphertext.
6. Here is an enciphered message
. The Friedman test results are: the index of coincidence is 0.0425 and
the estimated length of the keyword is 5.9105. Here are the frequencies of individual letters and of
the trigraphs . What method of
encipherment do you think was used? Explain why you think that was the
method that was used. Try to cryptanalyze the message. Explain how
you attacked the ciphertext.
