Cryptography review questions

Question: How does ECB mode encryption function?

Answer Choices:
A. Uses a self-synchronizing stream on the blocks, where the initialization vector (IV) is encrypted and XORed with the data stream
B. Converts from block to stream, then uses a counter value and a nonce to encrypt the data
C. Encrypts each block with the same key, where each block is independent of the others
D. Uses an initialization vector (IV) to encrypt the first block, then uses the result of the encryption to encrypt the next block

Answer: C – Encrypts each block with the same key, where each block is independent of the others

Question: What is the correlation between a block algorithm key size and its performance and security?

Answer Choices:
A. The key size is directly proportional to performance, but security is unaffected.
B. As the key size increases, performance and security also increase.
C. The key size is directly proportional to security, but performance is unaffected.
D. As the key size increases, performance decreases, and security increases.

Answer: D – As the key size increases, performance decreases, and security increases.

Question: What is the maximum key size of the Blowfish cipher?

Answer Choices:
A. 128
B. 192
C. 256
D. 448

Answer: D – 448

Question: Which secret key algorithm is used in the Clipper chip?

Answer Choices:
A. DES
B. IDEA
C. Blowfish
D. Skipjack

Answer: D – Skipjack

Question: How does a rainbow table crack stored passwords?

Answer Choices:
A. Takes a list of the most common words and tries each entry
B. Looks at the mathematical probability of paired values being used
C. Factors the prime numbers used within an RSA algorithm
D. Matches hash values back to the original plaintext

Answer: D – Matches hash values back to the original plaintext

Question: Which encryption algorithm uses an 80-bit key and operates on 64-bit data blocks?

Answer Choices:
A. Camellia
B. Twofish
C. Skipjack
D. Blowfish

Answer: C – Skipjack

Question: Which mode of operation makes the AES algorithm vulnerable to a copy-and-paste attack?

Answer Choices:
A. CFB
B. ECB
C. CBC
D. OFB

Answer: B – ECB

Question: What does the LM hash do to passwords that are fewer than 14 characters before using the DES?

Answer Choices:
A. Adds null characters to the end
B. Converts characters to lowercase
C. Concatenates the characters
D. Rotates characters with a Caesar cipher

Answer: A – Adds null characters to the end

Question: Which attack maps hashed values and original data?

Answer Choices:
A. Rainbow table
B. Dictionary
C. Brute-force
D. Birthday

Answer: A – Rainbow table

Question: Which mode of encryption encrypts each block independently?

Answer Choices:
A. OFB
B. CFB
C. CTR
D. ECB

Answer: D – ECB

Question: What is the length (in bits) of a SHA hash output?

Answer Choices:
A. 40
B. 80
C. 160
D. 320

Answer: C – 160

Question: Which mode of encryption uses an initialization vector (IV) for the first part of plaintext and then, to encrypt each subsequent part of plaintext, leverages the outcome from each preceding operation?

Answer Choices:
A. ECB
B. OFB
C. CFB
D. CBC

Answer: D – CBC

Question: Which mode of encryption uses a self-synchronizing stream encryption where the initialization vector (IV) is encrypted and XORed?

Answer Choices:
A. Electronic Code Book (ECB)
B. Cipher feedback (CFB)
C. Cipher block chaining (CBC)
D. Output feedback (OFB)

Answer: B – Cipher feedback (CFB)

Question: Why should a forensic investigator create a hash on a victim’s hard drive and the bitstream copy of the hard drive?

Answer Choices:
A. To establish who created the files on the drives
B. To certify the information on the drive is correct
C. To verify that the drives are identical
D. To identify if someone opened the drive

Answer: C – To verify that the drives are identical

Question: Which component is used to verify that a data entity was created?

Answer Choices:
A. AES
B. HMAC
C. NTLM
D. TSP

Answer: D – TSP