## Do I Know This Already Quiz

The "Do I Know This Already?" quiz helps you determine your level of knowledge of this chapter's topics before you begin. Table 12-1 details the major topics discussed in this chapter and their corresponding quiz questions.

 Foundation Topics Section Questions Introducing Cryptographic Services 1 to 5 Exploring Symmetric Encryption 6 to 10 Understanding Security Algorithms 11 to 15

1. What form of attack are all algorithms susceptible to?

a. Meet-in-the-middle b. Spoofing c. Stream cipher d. Brute-force

2. Which type of cipher achieves security by rearranging the letters in a string of text?

a. Vigenere cipher b. Stream cipher c. Transposition cipher d. Block cipher

3. In terms of constructing a good encryption algorithm, what does it mean to create an avalanche effect?

a. Changing only a few bits of a plain-text message causes the ciphertext to be completely different.

b. Altering the key length causes the ciphertext to be completely different.

c. Changing only a few bits of a ciphertext message causes the plain text to be completely different.

d. Altering the key length causes the plain text to be completely different.

4. Which of the following are techniques used by symmetric encryption cryptography? (Choose all that apply.)

a. Block ciphers b. Message Authentication Codes (MAC)

c. One-time pad d. Stream ciphers e. Vigenere ciphers

5. Which of the following is not a common stream cipher?

c. SEAL

6. Which of the following characteristics accurately describe symmetric encryption algorithms? (Choose all that apply.)

a. They are faster than asymmetric algorithms.

b. They have longer key lengths than asymmetric encryption algorithms.

c. They are stronger than asymmetric algorithms.

d. They are less complex mathematically than asymmetric algorithms.

e. They are slower than asymmetric algorithms.

f. They are weaker than asymmetric algorithms.

7. DES typically operates in block mode, where it encrypts data in what size blocks?

a. 56-bit blocks b. 40-bit blocks c. 128-bit blocks d. 64-bit blocks

8. Stream ciphers operate on which of the following?

a. Fixed-length groups of bits called blocks b. Individual digits, one at a time, with the transformations varying during the encryption c. Individual blocks, one at a time, with the transformations varying during the encryption d. Fixed-length groups of digits called blocks

9. Which statement accurately describes ECB mode?

a. In ECB mode, each 64-bit plain-text block is exclusive ORed (XORed) bitwise with the previous ciphertext block.

b. ECB mode uses the same 64-bit key to serially encrypt each 56-bit plain-text block.

c. ECB mode uses the same 56-bit key to serially encrypt each 64-bit plain-text block.

d. In ECB mode, each 56-bit plain-text block is exclusive ORed (XORed) bitwise with the previous ciphertext block.

10. What method does 3DES use to encrypt plain text?

a. 3DES-EDE

b. EDE-3DES

c. 3DES-AES

d. AES-3DES

11. Which of the following is not considered a trustworthy symmetric encryption algorithm?

a. 3DES

b. IDEA

12. In a brute-force attack, generally an attacker has to search through what percentage of the keyspace until he or she finds the key that decrypts the data?

a. Roughly 10 percent b. Roughly 75 percent c. Roughly 66 percent d. Roughly 50 percent

13. How many weak keys are a part of the overall DES keyspace?

14. Which of the following is not a component of the key management life cycle?

a. Key verification b. Key transposition c. Key generation d. Key exchange e. Key storage

15. Hashing is used to provide which of the following?

a. Data consistency b. Data binding c. Data checksums d. Data integrity

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