ECES Cryptography Practice

1. How did the ATBASH cipher work? a. By shifting each letter a certain number of spaces b. By Multi alphabet substitution c. By rotating text a given number of spaces d. By substituting each letter for the letter from the opposite end of the alphabet (i.e. A becomes Z, B becomes Y, etc.)

2. DES has a key space of what? a. 2^128 b. 2^192 c. 2^56 d. 2^64

3. Which of the following are valid key sizes for AES (choose three)? a. 56 b. 64 c. 128 d. 192 e. 256 f. 512

4. Which of the following algorithms uses three different keys to encrypt the plain text? a. AES b. 3DES c. Blowfish d. Skipjack

5. Which of the following is a block cipher? a. AES b. RC4 c. DH d. RSA

6. Which of the following is a type of encryption that has two different keys. One key can encrypt the message and the other key can only decrypt it? a. Symmetric b. Asymmetric c. Block cipher d. Stream cipher

7. Which of the following is an asymmetric cipher? a. DES b. RC4 c. RSA d. AES

8. A cipher is defined as what? a. Any algorithm used in cryptography b. The key used to encrypt a message c. The algorithm(s) needed to encrypt and decrypt a message d. Encrypted text

9. Which of the following is not an asymmetric system? a. DH b. AES c. RSA d. PGP

10. John is going to use RSA to encrypt a message to Joan. What key should he use? a. Joan's public key b. A shared key c. Joan's private key d. A random key

11. What advantage do symmetric algorithms have over asymmetric algorithms? a. They are faster b. They are more secure c. It is easier to exchange keys d. It is easier to implement them in software

12. Which of the following is generally true about key sizes? a. Larger key sizes increase security b. Smaller key sizes increase security c. Key size is irrelevant to security d. Key sizes must be more than 256 bits to be secure

13. A _____ is a function is not reversible. a. Stream cipher b. Asymmetric cipher c. Hash d. Block Cipher

14. Which of the following is a protocol for exchanging keys? a. EC b. RSA c. DH d. RSA

15. Which of the following would be the fastest? a. AES b. RSA c. DH d. EC

16. Which of the following would be the weakest encryption algorithm? a. AES b. RSA c. DES d. EC

17. What is the largest key size that AES can use? a. 56 b. 128 c. 256 d. 512

18. All of the following are key exchange protocols except for____ a. DH b. AES c. MQV d. ECDH

19. Which of the following is a key exchange protocol? a. RSA b. AES c. DES d. MQV

20. Which of the following encryption algorithms relies on the inability to factor large prime numbers? a. EC b. AES c. RSA d. MQV