2.8 Basic Cryptographic Concepts

Question 1

An unencrypted message (in the clear)

Answer 1

Plaintext

Question 2

An encrypted message

Answer 2

Ciphertext

Question 3

The algorithm used to encrypt/decrypt a message

Answer 3

Cipher

Question 4

The art of cracking encryption

Answer 4

Cryptanalysis

Question 5

True or false: Larger encryption keys are generally more secure.

Answer 5

true

Question 6

True or false: All encryption methods only use a single key.

Answer 6

False

Question 7

How can a small encryption key be used to make a stronger encryption?

Answer 7

Apply the key multiple times (stretching)

i.e. Hash a password. hash the hash. etc.

Question 8

Applications designed to take small keys and perform repetitive hashing with them in order to create stronger hashes.

Answer 8

Stretching libraries

Question 9

New standard of cryptography designed for IoT devices that have limited compute power.

Answer 9

Lightweight cryptography

Question 10

Encryption method intended to perform calculations on data while it is still encrypted. Assists with secure data stored in the cloud.

Answer 10

Homomorphic encryption (HE)

Question 11

Encryption method that uses one single key for encryption and decryption. Does not scale well but is fast with little overhead.

Answer 11

Symmetric encryption

Question 12

Public key cryptography. Involves two or more mathematically related keys, one public and one private.

Answer 12

Asymmetric encryption

Question 13

A form of asymmetric cryptography that uses large integers compose of two or more prime factors. Uses smaller keys and requires less storage. Good for mobile devices.

Answer 13

Elliptic curve cryptography

Question 14

Known as a message digest and is a short string of text that represents a set of data.

Answer 14

Hash

Question 15

What is one way to use hashing to verify downloaded files from a website?

Answer 15

Compare the hash on your downloaded content to the hash on the website

Question 16

True or false: When salting passwords, everybody gets a different salt stored with their password.

Answer 16

True

Question 17

Created using the private key and serves to prove that a piece of data was not changed, the source, and verify that it’s not fake

Answer 17

Digital signature

Question 18

True or false: Cryptographic algorithms are largely unknown entities

Answer 18

False

Question 19

Which encryption method has larger keys: symmetric or asymmetric?

Answer 19

Asymmetric

Question 20

What is a common length of key to see with asymmetric encryption?

Answer 20

3,072 bits or larger

Question 21

An encryption method that generates a session key on a server which allows a symmetric key to be sent via asymmetric encryption.

Answer 21

Real-time encryption

Question 22

Method of web traffic encryption that doesn’t use RSA keys. Uses elliptic curve or Diffie-Hellman and keys are not kept around. Requires more computing power and server/web browser must be compatible.

Answer 22

Perfect forward secrecy (PFS)

Question 23

The process of obscuring code in order to secure it.

Answer 23

Stenography

Question 24

Stenography technique which embeds messages into TCP packets.

Answer 24

Network Stenography

Question 25

What is the goal of all the different stenography types (network, image, audio, watermarks, etc.)

Answer 25

Hiding a message within the given media

Question 26

New type of computing that utlizes qubits as the smallest data form rather than bits with traditional computing.

Answer 26

Quantum computing

Question 27

What are some tasks quantum computing can tackle?

Answer 27

Quickly searching/indexing large databases

Simulating the quantum world (medical, weather, physics)

Question 28

How does quantum computing break existing crytpography much quicker than traditional computing methods?

Answer 28

It can quickly factor prime numbers

Question 29

This algorithm was created in 1994 to find prime factors of an integer N. Would take traditional computing longer than the age of the universe in order to solve.

Answer 29

Shor’s Algorithm

Question 30

A cryptosystem using lattice theory and relies on the “closest vector” problem.

Answer 30

NTRU

Question 31

Cipher type:

• Encryption is done one bit/byte at a time
• Used with symmetric encryption
• Starting state should never be the same twice (initialization vector)

Answer 31

Stream cipher

Question 32

Cipher type:

• fixed-length encryption groups
• 64 or 128 bit blocks
• Symmetric encryption

Answer 32

Block cipher

Question 33

The simplest encryption mode where each block is encrypted with the same key every time. Identical plaintext blocks create identical ciphertext.

Answer 33

Electronic code book (ECB)