| # | Date | Topic | Homework | 200-level |
|---|---|---|---|---|
| 1 | W 1/28 | Introduction | Read Ch. 1 of Code Book | - |
| 2 | F 1/30 | Shift ciphers: their encoding, decoding, cryptanalysis | - | - |
| 3 | M 2/2 | Associate letters with numbers mod 26. Modular arithmetic (Barr 2.1: 59-63) | HW 1: Barr p. 66 (2.1): 1, 2 (due 2/6) | - |
| 4 | W 2/4 | Decimation ciphers (Barr 2.2 p. 69-76) | HW 2: Barr p. 80 (2.2) 1,2 (due 2/9 Note change in due date) | - |
| 5 | F 2/6 | Affine ciphers (Barr 2.2): encryption, decryption, number of possible keys | - | - |
| 6 | M 2/9 | Transposition ciphers (Barr 2.4) | HW 3: p. 105: 1, 2, 4 (due 2/11) | - |
| 7 | W 2/11 | Cryptanalysis of an affine cipher | HW 4: p. 80 (2.2) 3ab, 4, 5ab, 7, 8, 9 (due 2/18) | - |
| 8 | F 2/13 | Substitution ciphers (Barr 2.3) | HW C1: Finish the deciphering of the example we started in class. (You'll probably want to work in a group with a few others.) (due 2/18) | - |
| 9 | M 2/16 | Vigenere cipher (2.5) | HW 5: (2.5) p. 118: 1a, 2a; p. 105 (2.4): 6. (Due 2/23) | - |
| 10 | W 2/18 | Keyword columnar transposition ciphers: their encryption, decryption and cryptanalysis (2.4) | (see added problem in HW 5 above) | - |
| 11 | F 2/20 | Quiz | - | - |
| 12 | M 2/23 | Cryptanalyse Vigenere when keyword length is known (Barr p. 111-15) | - | Read p. 158-166 on Hill ciphers. HW A: p. 172: 1ab, 2ab, 3ab, 4 (Due 2/28) |
| 13 | W 2/25 | The Kasiski test for finding the length of keyword in a Vigenere ciphertext (Barr p. 139-140) | HW 6: p. 118 (2.5): 5,6; p. 141 (2.7): 8 (Due 3/1) | - |
| 14 | F 2/27 | Permutations and combinations (2.6) | HW 7: p. 130 (2.6) 1ab, 2ab, 3 (Due 3/10) | - |
| 15 | M 3/1 | Quiz 2 (transposition, Vigenere ciphers); Friedman's Index of Coincidence (2.7) | HW 8: p. 141 (2.7): 1ab, 3 (Due 3/10) | - |
| 16 | W 3/3 | IC (con't) | Calculating the index of coincidence using excel. | - |
| 17 | F 3/5 | Demo use of IC to find keyword length using Quenell's web site and Excel | - | - |
| 18 | M 3/8 | Test I (on material through 2/20) | - | - |
| 19 | W 3/10 | Polybius cipher [Barr p. 5, Kahn p. 83, 203-4] | - | - |
| - | - | Homophonic ciphers [Singh p. 52f, Kahn p. 107, 113] | HW 9 p. 32: 8, 14; p. 94: 7 (Due 3/24) | - |
| - | - | Alberti cipher disk [Barr p. 7, Kahn p. 125-130] | Read David Kahn, The Codebreakers, p. 125-130 | - |
| 20 | F 3/12 | Demonstration of Using Excel to do shift ciphers. to do shift ciphers [Barr p. 63]. Also trying all possible keys to solve shift ciphers. | HW 10 (Use Excel): Do problem 1 p. 66 for practice. Then solve the following ciphertest (produced with a shift cipher): LFDPH LVDZL FRQTX HUHG (Due 3/24) | - |
| - | - | - | Relaxing reading for break (optional, of course!): The Adventure of the Dancing Men (Sherlock Holmes). Also Poe's The Gold Bug | - |
| 21 | M 3/22 | Playfair cipher (Barr p. 16, Singh Appendix E, Kahn p. 198-202)) | HW 11: p. 36: 16, 17 (on Playfair cipher). Read about Jefferson's cipher wheel (Barr p. 15) and do homework problem 15, p. 35. (Due 3/29) | - |
| - | - | ADFGVX cipher (Barr p. 21, Singh p. 374) | Read Kahn p. 339-350 | - |
| 22 | W 3/24 | Description of the Engima | Read Barr p, 23-25, Singh ch 3 p. 124-142, also chapter ch. 4 | - |
| 23 | F 3/26 | The Enigma (con't) | HW 12: Send and receive with the Enigma: Use the simulator on my web page. Choose a partner with whom you will exchange messages. Each of you send a message to the other in the proper way: Set up the machine as in the top of the handout. First send a three letter message key, repeat this, change the rotors to these three letters, and send the message. Then each person writes a brief report with the message key sent and message sent, and message key received with message received. | - |
| 24 | M 3/29 | Prime numbers [Barr 4.1] | HW 13: p. 260: 1, 2, 4, 5, 6ab (Due 4/5) | - |
| 25 | W 3/31 | Modular exponentiation [Barr p. 275] | - | - |
| 26 | F 4/2 | RSA cipher [Barr 4.4] | Read Singh Ch. 6 | - |
| 27 | M 4/5 | Extended Euclidean algorithm to find modular inverses [Barr p. 254f.] | HW 14: p. 261: 11ab, 12ab; p. 293: 1, 2, 4, 5 (Due 4/12) | - |
| - | - | - | Solve Cryptogram 1 (Due 4/12). | - |
| 28 | W 4/7 | Encoding/decoding letters into numbers mod 26 (Barr p. 288f.) | - | - |
| 29 | F 4/9 | Discrete Log Problem [Barr p. 297] | - | - |
| - | - | Diffie-Hellman key exchange [Barr p. 299] | HW 15: p. 304: 1ab, 5; also see below (Due 4/14) | - |
| 30 | M 4/12 | Atbash cipher [Barr p. 3, Kahn p. 77-79] | HW 15 (con't): p. 32: 1, 2 | - |
| - | - | Demonstration of RSA using Maple | - | - |
| - | - | - | Reading: Sharing the Burden: Women in Cyrptology during WWII | - |
| 31 | W 4/14 | Test II (on material through 3/29, also description of RSA cipher): Two parts: in-class test on Wednesday, and take-home part due Friday 4/16 at beginning of class. | Question 3 on take-home test | - | 32 | F 4/16 | Video "Spies" (WW II) | - | - |
| 33 | M 4/19 | Binary numbers, XOR, ASCII [Barr 3.1, p. 200, p. 64] | HW 16: p. 185: 1ab, 2ab, 4; p. 200: 2 (Due 4/26) | Do some of Introduction to Maple and do some of the Exercises using Maple (enough to acquaint you with the program). Then do HW B below with help from Maple commands for cryptology (Due 4/26) |
| 34 | W 4/21 | DES [Barr 5.1] | - | - |
| 35 | F 4/23 | Digital signatures | HW 17: p. 312: 1, 2 (Due 4/28) | - |
| 36 | M 4/26 | Rijndael | - | - |
| 37 | W 4/28 | M-209-B | Cryptograms in foreign languages. Use Letter frequencies in foreign languages. | - |
| 38 | F 4/30 | Visualizing Rijndael | HW 18: See below (Cancelled) | - |
| 39 | M 5/3 | - | - | - |
| - | T 5/4 | - | All homework and rewrites (except ..) due at 5pm today | - |
Homework 18: Using Rijndael. For this assignment use the javascript version of Rijndael written by Fritz Schneider. Note that the key, plaintext and ciphertext are 32 hexadecimal digits (256 binary digits). Enter these without spaces. Use the Table of numbers and letters converted to ASCII binary and hexadecimal numbers. Since each letter or number corresponds to two hexadecimal digits, a block will be 16 letters.