Assignment 8: Cryptography

16 December 2019   PDF version

There are two parts to this assignment. Provide the requested answers and information on (or attached to) a GitLab wiki page called A8 in your main CS101 repository.

(1) Monoalphabetic cipher

Below are individualized links pieces of text encoded using a single-substitution (monoalphabetic) cipher. Your task is to crack the code and discover the secret poem. You should start by doing a frequency analysis of the letters in your text.

When finished, take a picture of your decrypted text, and attach it to your wiki page.

AL 9482 text16.crypt.pdf
AM 6470 text23.crypt.pdf
AM 9063 text12.crypt.pdf
AN 2026 text11.crypt.pdf
AR 8693 text09.crypt.pdf
AW 1120 text07.crypt.pdf
BJ 1758 text10.crypt.pdf
CB 0786 text04.crypt.pdf
CD 7177 text04.crypt.pdf
CF 7260 text05.crypt.pdf
CO 2217 text12.crypt.pdf
EV 1014 text06.crypt.pdf
GA 5341 text21.crypt.pdf
GR 3209 text17.crypt.pdf
HT 4995 text20.crypt.pdf
IP 7121 text03.crypt.pdf
JC 3866 text18.crypt.pdf
JV 2547 text14.crypt.pdf
KB 2597 text15.crypt.pdf
KG 0351 text03.crypt.pdf
KH 8171 text08.crypt.pdf
KR 8920 text11.crypt.pdf
KV 3181 text16.crypt.pdf
LC 5362 text22.crypt.pdf
LF 7631 text07.crypt.pdf
LJ 2323 text13.crypt.pdf
LJ 9222 text15.crypt.pdf
LK 6885 text02.crypt.pdf
MB 1002 text05.crypt.pdf
ML 4201 text19.crypt.pdf
MZ 8853 text10.crypt.pdf
NP 9205 text14.crypt.pdf
OS 1559 text09.crypt.pdf
SA 9088 text13.crypt.pdf
TR 7435 text06.crypt.pdf
VB 0068 text02.crypt.pdf
XW 1354 text08.crypt.pdf

(2) Vigenère cipher

  1. Choose a password that is 5–8 letters, and write it down.
  2. Write down a sentence that is about 4–6 times the length of your password.
  3. Use the polyalphabetic substitution table to encode the sentence using your password.
  4. Type the encrypted sentence and the password directly into your wiki page (does not need to be an attachment).
  5. You’ll get full credit for this portion only if I can make sense of your sentence by decrypting using your password. So you may want to give that a test run with a friend: give them your encrypted sentence and password, and see if they get it right.