- Encode the following sentence using the simple polyalphabetic code
of period three using ROT3, ROT13, ROT7.
Carolina beat Vanderbilt.
I was expected three separate encodings, but accepted the polyalphabetic solution.
ROT3 FDUROLQD
ROT 7 JHYVSPUH
ROT 13 PNEWYVAN
Polyalphabetic: ROT3 first, ROT13 second, ROT7 next ... FNYRYPQN
- Decode the text below which was encoded with a simple substitution,
(not necessarily a rotation). Implemented by Substitution.c.
mqphbeapkhqqpybstaeubpbuzpieugpkhopheghpwsbeiqX
mekhpatobapzqltketupsqvqvxqseugpkhqpzboX
mhqupwstjzaopmqpitjghkpkhqqpkhopyheazsqupktpxqX
hqsq*ipbphqbakhpybstaeubpftsqlqspktpkhqqX
Hint '*' is an apostrophe and '\n' is mapped to "X ", only lower case
characters and a space.
we hail thee carolina and sing thy high praise
with loyal devotion remembering the day
when proudly we sought thee thy children to be
here's a health carolina forever to thee
- Design an homophonic encryption code based on the frequencies
of characters in English (from the handout for assignment 2).
This code should be designed so that all output codes are
roughly equally likely:
The letters should "ZJQXK" have one code "33" of frequency .78%
Every other character should have at least one output code
and the number of codes should be such that the frequency was roughly 1.0%.
Space needs 18 codes
T needs 8
AIORSN each needs 6
H needs 4
CLD each needs 3
MUPFG each needs 2
BWYV each needs only one
- Finalize the computations on the number of initial states of:
- the initial 3 rotor Enigma
- the Enigma with the 7 pair plugboard
- the final Enigma with 5 rotors of which any three could be used
in any position and the plugboard
Write the answer in terms of combinations and powers then expand
using a calculator.
- Given p = 101 and q = 113 Compute n, phi(n), choose b = 3533,
show that b and phi(n) are relatively prime.
Compute the private key.
p = 101 q = 113
n = 11413
phi(n) = 100*112 = 11200
e = 3533
6579 calculated with extEuclidean
- Using the square and multiply algorithm to encode the plaintext 9726.
Check your answer by using the private key to decode the message.