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Khan Academy Cryptography

Total questions: 10

Worksheet time: 6mins

Name
Class
Date
1.

In order for a one-time pad to work properly, the key must:

a)

Be as long as the message

b)

Be created using a multi-sided die

c)

Be created using a random number generator

d)

One-time pads are inherently secure because they are never used twice

2.

Poly-alphabetic ciphers are:

a)

used to flatten the letter pattern frequency

b)

impossible to solve because of the randomness of the letters

c)

secure because they do not leak information

d)

easy to solve because there are fewer possibilities to consider

3.

Poly-alphabetic ciphers use ______________ to encode messages

a)

shift keys

b)

one-time pads

c)

RSA encryption

d)

multiple languages

4.

Poly-alphabetic ciphers are more secure based on

a)

The length of the key

b)

The length of the message

c)

The time it takes to transmit the message

d)

The power of the computer encoding it

e)

t

5.

The Caesar cipher is a _____________

a)

substitution cipher

b)

military-grade encryption

c)

unbreakable code

d)

very difficult to decode

6.

The maximum number of possibilities for a Caesar cipher in ENGLISH is:

a)

25

b)

26

c)

about 15,000

d)

about 2 million

7.

Frequency analysis is

a)

determining the % of time a letter appears in a given language

b)

determining the % of times an encryption key is used

c)

determining how often a Caesar cipher is repeated

d)

a complex mathematical formula usually conducted using super computers

8.

What is the solution to this "classic" Caesar cipher?

Kdssb Kdoorzhhq

(a)  

9.

Encode WATER using a Caeser cipher with a +2 shift

(a)  

10.

How can you determine if a sequence of numbers is truly random?

a)

By counting the occurrence of each number

b)

By using the frequency stability property

c)

By using the enigma theory of randomness

d)

There is no way to determine this

e)

b