#33

Question 1

What uses many layers of varying security mechanisms to frustrate attackers?

Answer 1

Defense in depth

Question 2

One of the most common forms of computer security?

Answer 2

Cryptography

Question 3

The word cryptography comes from roots ‘crypto’ and ‘graphy’ roughly translating to what?

Answer 3

Secret writing

Question 4

In order to make information a secret you use what?

Answer 4

Cipher

Question 5

What is an algorithm that converts plain text into cipher text, which is gibberish unless you have a key that lets you undo the cipher?

Answer 5

Cipher

Question 6

The process of making text secret

Answer 6

encryption

Question 7

the reverse process of encryption

Answer 7

decryption

Question 8

Encryption and decryption are the same thing you just have to make sure the _________ and ________ machines have the same initial configuration.

Answer 8

sending and receiving

Question 9

Julius Caesar used what is now called a _______ _______, to encrypt private correspondence. He would shift the letters in a message forward by three places. To decipher the message, recipients had to know both the ________ and the _______ to shift by, which acted as the key.

Answer 9

Caesar Cipher

algorithm and number

Question 10

The Caesar Cipher is one example of a larger class of techniques called substitution ciphers. These replace every letter in a message with something else according to a translation.

Answer 10

True

Question 11

A skilled cryptanalyst can work backwards from these kinds of statistics to figure out the message.

Answer 11

Cryptanalyst

Question 12

Here we take a message and fill the letters into a grid. To encrypt the message you read out the characters in a different order. Example from the bottom left working upwards one column at a time. This is known as what?

Answer 12

Columnar transposition Cipher

Question 13

New letter ordering is the encrypted message. This is what?

Answer 13

Permutation

Question 14

The ordering direction, as well as the 5 by 5 grid size serves as the what?

Answer 14

Key

Question 15

What was used by the nazis to encrypt their wartime communications?

Answer 15

German Enigma

Question 16

What was a typewriter like machine, with a keyboard and lapboard, both showing the full alphabet. Above that there was a series of configurable rotors that were the key to the Enigma’s encryption capability.

Answer 16

Enigma

Question 17

What device has one side with electrical contacts for all 26 letters. These connected to the other side of the rotor using cross-crossing wires that swapped one letter for another.

Answer 17

Enigma Rotor

Question 18

Letter swapping behavior is a what?

Answer 18

Substitution Cipher

Question 19

Following the rotors was a special circuit called? Instead of passing the signal onto another rotor, it connected every pin to another and sent the electrical signal back through the rotors.

Answer 19

Reflector

Question 20

There is a _________ at the front of the machine that allows letters coming form the keyboard to be optionally swapped, adding another level of complexity.

Answer 20

plugboard

Question 21

To prevent the ______ from being a simple;e substitution cipher, every single time a letter was entered the rotors advanced by one spot, sort of like an odometer in a car.

Answer 21

Enigma

Question 22

One of the earliest software ciphers to become widespread was the ________ _______ ______ developed by IBM and NSA in 1977.

Answer 22

Data Encryption Standard

Question 23

DES as it was known originally used ______ keys that were 56 bits long, which means that there are 2 to the 56 or about 72 quadrillion different keys.

Answer 23

Binary

Question 24

in 2001 the ________ _______ _______ was finalized and published. AES if designed to use much bigger keys 128,192,256 bits in size making brute force attacks much harder.

Answer 24

Advanced Encryption Standard

Question 25

AES chops data up into _____ _____ ___, and then applies a series of substitutions and permutations, based on the key values plus some other operations to obscure the message, this process is repeated ten or more times for each block.

Answer 25

16 byte-blocks

Question 26

AES balances performance and security to provide practical cryptography. Today, AES is used everywhere from encrypting files on iPhones and transmitting data over WIFI with WPA2 to accessing websites using HTTPS.

Answer 26

True

Question 27

The sender encrypts a message using a ___. and the recipient decrypts it using the same _____.

Answer 27

Key

Question 28

What is an algorithm that lets two computers agree on a ket without ever sending one. We can do this with one way functions- mathematical operations that are very easy to do in one direction but hard to reverse?

Answer 28

Key exchange

Question 29

Paint Colors as an analogy- easy to mix but not easy to figure out. Example of what?

Answer 29

Key Exchange

Question 30

The one way function is modular exponentiation. This means taking one number, the use, to the power of another number, the exponent, and taking the remainder when deciding by a third number, the modulus?

Answer 30

Diffie Hellman Key Exchange

Question 31

Diffie Hellman used to calculate a what?

Answer 31

Shared Key

Question 32

What are the keys that can be used by both sender and receiver to encrypt and decrypt messages. They are called this because the key is the same on both sides

Answer 32

Symmetric Keys

Question 33

The Caesar Cipher, Enigma and AES are all what?

Answer 33

Symmetric Keys

Question 34

What is when there are two different keys, often one is public and one is private?

Answer 34

Asymmetric encryption

Question 35

Knowing the public key only lets you encrypt because it is

Answer 35

Asymmetric

Question 36

Think about boxes with padlocks that you can open with a key. To receive a secure message, I can give sender a box and padlock and they put their message private key. After locking the box, neither the sender nor anyone else who finds the box can open it without brute force.

Answer 36

Asymmetric Encryption

Question 37

Where a server encrypts data using their private key. Anyone can decrypt it suing the server’s public key. This acts like an unforgivable signature, as only the owner using their private key, can encrypt it?

Answer 37

signing

Question 38

The most popular asymmetric encryption technique used today is RSA, named after its inventors; Rivest, Shamir, and Adleman

Answer 38

True

Question 39

The little lock icon that your computer has used public key cryptology to verify the server, key exchange to establish a secret temporary key, and symmetric encryption to protect all the back and fourth communication.

Answer 39

True