Cryptography

Question 1

Modular Math

Answer 1

Lies behind much of cryptography.

Simply put, Modular Math shows you what remains (the remainder).

Question 2

Caesar Cipher

Answer 2

A monoalphabetic rotation cipher used by Gaius Julius Caesar.

Question 3

Transposition Ciphers

Answer 3

Use an encryption algorithm to rearrange letters of a plaintext message, forming the ciphertext message. The decryption algorithm simply reverses the encryption transformation

Question 4

Substitution Ciphers

Answer 4

Use the encryption algorithm to replace each character or bit of the plaintext message with a different character.

Question 5

One-Time Pads

Answer 5

An extremely powerful type of substitution cipher. One-Time pads use a different substitution alphabet for each letter of the plaintext message.

Question 6

Running Key Ciphers

Answer 6

In this cipher, the encryption cipher is as long as the message itself and is often chosen from a common book.

Question 7

Block Ciphers

Answer 7

Operates on “chunks” or blocks, of message and apply encryption to an entire message block at the same time.

Question 8

Stream Ciphers

Answer 8

Operates on one character or bit of a message (or data stream) at a time.

Question 9

Confusion

Answer 9

Occurs when the relationship between the plaintext and the key is so complicated that an attacker cannot merely continue altering the plaintext and and analyzing the resulting ciphertext to determine the key.

Question 10

Diffusion

Answer 10

Occurs when a change in plaintext results in multiple changes spread throughout the ciphertext.

Question 11

Data Encryption Standard

Answer 11

64-bit block cipher
56-bit key
Long series of XOR operations
16 rounds

Question 12

DES Modes

Answer 12

Electronic Codebook Mode
Cipher Block Chaining Mode
Cipher Feedback Mode
Output Feedback Mode
Counter Mode