EC-Council Certified Encryption Specialist

EC-Council Certified Encryption Specialist Practice Questions 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. 2128 b. 2192 c. 256 d. 264 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 21. Using substitution without transposition leads to what weakness? a. None, this is a valid approach b. Letter/word frequency is maintained c. The key can easily be derived d. It is vulnerable to chosen ciphertext attacks 22. What algorithm does the clipper chip use? a. Blowfish b. Twofish c. Skipjack d. PIKE 23. What size key does Skipjack use? a. 56 bit b. 80 bit c. 128 bit d. 256 bit 24. What size block does Skipjack use? a. 64 b. 128 c. 256 d. 512 25. With Electronic codebook (ECB) what happens a. The cipher text from the current round is XORed with the plaintext for the next round. b. The cipher text from the current round is XORed with the plaintext from the previous round. c. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption. d. The block cipher is turned into a stream cipher 26. Which algorithm implements an unbalanced Feistel cipher? a. Skipjack b. 3DES c. RSA d. Blowfish 27. With Cipher-block chaining (CBC) what happens? a. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption. b. Each block of plaintext is XORed with the previous ciphertext block before being encrypted c. The cipher text from the current round is XORed with the plaintext for the next round. d. The block cipher is turned into a stream cipher 28. With Cipher feedback (CFB) what happens? a. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption. b. The ciphertext block is encrypted then the ciphertext produced is XOR’d back with the plaintext to produce the current ciphertext block. c. The block cipher is turned into a stream cipher d. The key is reapplied 29. What does Output feedback (OFB) do? a. The cipher text from the current round is XORed with the plaintext for the next round. b. The cipher text from the current round is XORed with the plaintext from the previous round. c. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption. d. A block cipher is converted into a stream cipher by generating a keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext 30. Which of the following modes cannot be used to turn a block cipher into a stream cipher? (select 2) a. CTR b. PCBC c. CFB d. ECB e. OFB 31. What is an IV? a. A fixed size random stream that is added to a block cipher to increase randomeness. b. Random bits added to a hash. c. The key used for a cryptography algorithm d. The cipher used. 32. A number that is used only one time, then discarded is called what? a. Nonce b. IV c. Salt d. Chain 33. What is the largest key size that RC4 can use? a. 56 bits b. 128 bits c. 256 bits d. 512 bits 34. What is the basis for the FISH algorithm? a. The difficulty in factoring numbers b. The Lagged Fibonacci generator c. Equations that describe an ellipse d. Prime number theory 35. Which of the following is required for a hash? a. Variable length input, fixed length output b. Few collisions c. Minimum key length d. Not reversible e. Not vulnerable to a brute force attack f. Must use SALT 36. Which of the following is used to encrypt email and create digital signatures? a. AES b. SHA1 c. RSA d. DES 37. Bob’s password is hashed, and so is John’s. Even though they used different passwords, the hash is the same. What is this called? a. A mistake b. Convergence c. Transposition d. A collision 38. In relationship to hashing, the term _____refers to random bits that are used as one of the inputs to the hash. Essentially the is intermixed with the message that is to be hashed a. IV b. Vector c. Salt d. Stream 39. This is a 128 bit hash that is specified by RFC 1321. It was designed by Ron Rivest in 1991 to replace an earlier hash function. a. SHA1 b. RSA c. SHA256 d. MD5 40. This hash function uses 512-bit blocks and implements preset constants that change after each repetition. Each block is hashed into a 256-bit block through four branches that divides each 512 block into sixteen 32-bit words that are further encrypted and rearranged a. SHA1 b. RSA c. SHA256 d. FORK256 41. Which of the following is an asymmetric algorithm that was first publically described in 1977? a. RSA b. Elliptic Curve c. Twofish d. DESx 42. Which of the following equations describes the encryption process for RSA? a. Me % n b. P = Cd % n c. De % n + B d. y2 = x3 + Ax + B 43. Which of the following is an asymmetric algorithm related to the equation y2 = x3 + Ax + B? a. Blowfish b. AES c. RSA d. Elliptic Curve 44. Which of the following asymmetric algorithms is described by U.S. Patent 5,231,668 and FIPS 186 a. RSA b. AES c. RC4 d. DSA 45. Which of the following is the standard for digital certificates? a. X.509 b. CA c. CRL d. RFC 2298 46. Rather than look in a list, one can use a protocol to find revoked certificates. What protocol is that? a. RFC b. IPSec c. CRL d. OCSP 47. What must occur in order for a cipher to be considered ‘broken’? a. Finding any method that is more efficient than brute force. b. Uncovering the algorithm used c. Decoding the key d. Rendering the cipher no longer useable 48. ____________cryptography uses one key to encrypt a message and a different key to decrypt it. a. Asymmetric b. Symmetric c. Stream d. Secure 49. If the round function is a cryptographically secure pseudorandom function, then ___ rounds is sufficient to make the block cipher a pseudorandom permutation. a. 2 b. 3 c. 15 d. 16 50. If the round function is a cryptographically secure pseudorandom function, then ___rounds is sufficient to make it a "strong" pseudorandom permutation. a. 3 b. 4 c. 15 d. 16