Do these problems on your own,
without any collaboration with or help from others.
(See the statement of the College's academic honesty policy.)
Trim "fringes."
Solutions will be graded
on the basis of clarity of presentation
as well as correctness.
See also the lab assignments.
| Problem number | Problem | Due date |
|---|---|---|
| 1 | 100 consecutive letters of random text
and the individual letter frequencies | 1/3 |
| 2 | Complete the solution. | 1/4 |
| 3 | Solve the 3 crypts from Cryptograms and Spygrams. | 1/4 |
| 4 | Make a table showing the multiplicative inverses (reciprocals) modulo 26 of the numbers 1, 2, 3, 4, ... , 25, 26. (Some do not exist.) Keep a copy for your reference. | 1/5 |
| 5 | Little Orphan Annie crypt | 1/8 |
| 6 | "The Gold-Bug" cipher | 1/12 |
| 7 | Decipher the autokey crypt (with priming key "P"): ITKO GCRV | 1/11 |
| 8 | Complete the solution of the Vigenere case study of Jan. 11. | 1/12 |
| Extra
credit | Solve Exam 2 #10 | 1/16 |
| 9 | Using a Playfair square
(with I=J) based on the keyword "GUSTAVUS" (or "GUSTAV") ...
(a) encipher "This message calls for nulls" and (b) decipher KFHEV AXSPC. Using instead keyword "ADOLPHUS", decipher LMFVM EHAFR IGFWV IQZ? |
1/17 |
| 10 | ||
| 11 | Let g = gcd(345, 543). (a) Find g. (b) Find integers s and t such that 345 s + 543 t = g. (c) Solve 345 x = 12 (mod 543). | 1/19 |
| Extra
credit | Solve the NSA challenge posted outside my office. | 1/25 |
| 12 | Using the keyword "KEYS," encipher the plaintext "I solved your problems" (a) as a complete columnar transposition and (b) as an incomplete columnar transposition. | 1/24 |
| 13 | Using the columnar transposition keyword "KEYS," decipher (a) WLXPO IAIUF SMDEE ALEBR (b) ORNER YEIWC YCAYE ZUTLR A. | 1/24 |
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