Khan Academy Cryptography

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

• Be as long as the message

• Be created using a multi-sided die

• Be created using a random number generator

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

Poly-alphabetic ciphers are:

• used to flatten the letter pattern frequency

• impossible to solve because of the randomness of the letters

• secure because they do not leak information

• easy to solve because there are fewer possibilities to consider

Poly-alphabetic ciphers use ______________ to encode messages

• shift keys

• one-time pads

• RSA encryption

• multiple languages

Poly-alphabetic ciphers are more secure based on

• The length of the key

• The length of the message

• The time it takes to transmit the message

• The power of the computer encoding it

• t

The Caesar cipher is a _____________

• substitution cipher

• military-grade encryption

• unbreakable code

• very difficult to decode

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

• 25

• 26

• about 15,000

• about 2 million

Frequency analysis is

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

• determining the % of times an encryption key is used

• determining how often a Caesar cipher is repeated

• a complex mathematical formula usually conducted using super computers

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

Kdssb Kdoorzhhq

Encode WATER using a Caeser cipher with a +2 shift

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

• By counting the occurrence of each number

• By using the frequency stability property

• By using the enigma theory of randomness

• There is no way to determine this

• b