Math 4161
January 5, 2015
Cryptography is the science of secret writing, enabling the condentiality
of communication through an insecure channel.
Basic objectives of cryptography:
1. Condentiality - keep information secret from unauthorized parties.
2. Da
Math 4161
January 14, 2015
Letter Frequency Analysis
Estimated probabilities of occurrence of the letters:
letter
A
B
C
D
E
F
G
probability
0.082
0.015
0.028
0.043
0.127
0.022
0.020
letter
H
I
J
K
L
M
N
probability
0.061
0.070
0.002
0.008
0.040
0.024
0.06
Math 4161
January 09, 2015
Numbers
1 Denition. Let a, b Z.
We say a divides b if b = ac, for some integer c. We write a | b.
The greatest common divisor of a and b, denoted by gcd(a, b), is the largest
positive integer that divides both a and b.
We say
Math 187 - Cryptography
Garsia - Spring 2013
QUIZ 7
Name:
PID:
You may use your notes. You may not use your neighbors. You will need a calculator. Show all your work.
(1) Consider the random cryptosystem pictured here:
Suppose that m1 is chosen with proba
Math 4161 Assignment 3
Due on Monday April 13 at 11:30 a.m.
Submit your solution in class.
1. Denition: Let n be a positive integer. A Latin square of order n is
an n n array L whose entries are the integers 1, . . . , n such that each
number appears exac