Describe how each of the following attacks might be performed on the Vigenre

cipher:

(a)

A ciphertext-only attack.

(b)

A known-plaintext attack.

(c)

A chosen-plaintext attack.

(d)

A chosen-ciphertext attack

1. Assuming you have four-sided dice where the sides are labelled 1, 2, 3, and 4, answer the following questions.

a. Given a single four-sided die where each number is equally likely to be rolled, what is the probability of rolling each of the four numbers?

b. What is the entropy of the system of rolling a single four-sided die?

c. Given two four-sided dice, list out all possible outcomes of rolling the dice, where an outcome is the sum of the two numbers rolled. (For example, rolling a one and a three is the same outcome as rolling a two and a two).

d. What is the probability of each of the outcomes of rolling two four-sided dice (hint: there are 24=16 different combinations of two dice, each of which is equally likely, but many of them result in the same outcome)?

e. What is the entropy of the system of rolling two four-sided dice?