Domain 5: Cryptography

Question 1

IDEA Algorithm

Answer 1

120 Bit Key. 64 Bit Block. 8 Rounds

Question 2

CAST-256

Answer 2

128 Bit Block. 128, 192, 160, 224, 256 Bit Keys

Question 3

Message Authentication Code (MAC)

Answer 3

Message Auth and Integrity similar to hash.

Question 4

MAC vs HMAC

Answer 4

MAC: Sender encrypts small block of data with shared secret key. HMAC: Secret key is appended to original message.

Question 5

Key Space

Answer 5

Number of keys that can be created based on the key length in bits

Question 6

Two Way Algorithm

Answer 6

Math function that may both encrypt and decrypt a message

Question 7

Work factor

Answer 7

Time and effor that it takes to break a specific encrypted text

Question 8

Initialization vector

Answer 8

Unencrypted random number that is used to create complexity during the encryption process. Enhances the effect of the key.

Question 9

Key clustering

Answer 9

When two different crypto keys create the same ciphertext from same plain text. Indicates flaw

Question 10

Transposition

Answer 10

Method of placing plaintext horizontally into a grid and reading grid virtually.

Question 11

Confusion

Answer 11

Increases complexity of encrypted message by modifying they key during the encryption process. Increases work factor.

Question 12

Diffusion

Answer 12

Increases complexity of encrypted message.

Question 13

Block Cipher Modes

Answer 13

ECB, CBC CFB, OFB

Question 14

ECB

Answer 14

Electronic Code Book. Most basic. Blocks of 64 bits are input into an algorithm.

Question 15

CBC

Answer 15

Cipher Block Chaining. Plaintext is combined or XOR’d ith IV block by block. Then each block is encypted into the next block.

Question 16

CFB

Answer 16

Cipher Feedback mode. Stream cipher mode. Bit shifted out and encrypted with bit from plaintext shift register.

Question 17

OFB

Answer 17

Output feedback mode. Stream cipher mode. CFB with encrypted IV.

Question 18

Counter mode

Answer 18

Stream cipher mode. Similar to OFB, but uses 64-bit random counter instead of IV.

Question 19

Cipher Suite

Answer 19

Mostly refers to SSL/TLS collection of algorithms. TLS_DHE_DSS_WITH_DES_CBC_SHA

Question 20

Chosen ciphertext attack

Answer 20

Attacker has access to encryption mechanism and public or private key and can process ciphertext in order to detect the algorithm.

Question 21

Key encrypting key (kek)

Answer 21

Shared master key used to encrypt and exchange session keys.

Question 22

Zeroisation: “Clearing.”

Answer 22

Erasing key from electronic device or memory module.