1) The Chinese remainder theorem is used to speed-up ____________ Select one: a. El Gamal decryption b. None of the options c. RSA decryption d. RSA Encryption

2) The algorithm which forms the basis of ElGamal cryptosystem is ____________ Select one: a. Die-Hellman b. DSA c. RSA d. Elliptic curve

3) A brute-force attack on a MAC is easier than a brute-force attack on a hash function Select one: a. True b. False

4) The objective of Die-Hellman Key exchange is __________ Select one: a. To protect encrypted data from man-in-the-middle attack b. To establish a shared secret key on both sides c. To send a symmetric secret key over an insecure channel d. To provide authentication services to both parties

5) We would like to compute the multiplicative inverse of 9 modulo 17. Which algorithm do you typically use to compute this? Select one: a. Primality algorithm b. Miller-Rabin algorithm c. Extended Euclidean algorithm d. Chinese remainder algorithm

6) Would Bob get a perfect RSA system if he lets n be a prime number, rather than a product of two prime numbers p and q? Select one: a. It depends on the size of n b. It depends on the size of plaintext c. Yes d. No

7) In asymmetric cryptography, which of the following must be true? Select one: a. Dierent algorithms are used for encryption and decryption b. None of the options c. Encryption function is one-way and it is impossible to reverse it d. Encryption takes much longer than decryption

8) Asymmetric cryptography is not preferred because Select one: a. It is hardware/software intensive b. All the options c. It cannot be used for real time trac d. It has a high computational overhead

9) The square and multiply mechanism is used to speed-up ____________ Select one: a. RSA encryption and decryption b. All the options c. RSA decryption d. RSA encryption e. The extended Euclidean algorithm

10) Hash collision means _____________ Select one: a. Two hash outputs for two messages b. Two hash outputs for one message c. One hash output for two messages d. None of the options

11) The preimage resistance security property is dened as: Select one: a. Given x1, and thus h(x1), it is computationally infeasible to nd any x2 such that h(x1) = h(x2) b. For a given output z, it is computationally feasible to nd an input x such that h(x) = z c. None of the options d. It is computationally infeasible to nd any pairs x1 x2 such that h(x1) = h(x2)

12) In RSA cryptosystem, which one of the following numbers is the largest? Select one: a. e b. q c. p d. n

13) __________ allows communicating parties to verify that received or stored messages are authentic Select one: a. Hash function b. MAC c. Collision resistance d. Decryption

14) If we choose a perfect hash function, then there are no two inputs that can hash to the same value Select one: a. True b. False

15) Regardless of the nature of the mathemtical function used in asymmetric cryptography, we can always assume that given the public key, it is computationnaly infeasible to nd the private key Select one: a. False b. True

16)You wish to send 1024 bytes message to Alice. If you use the SHA-1 hashing algorithm, what size will the message be? Select one: a. 512 bites b. 1024 bits c. 1024 bytes d. None of the options e. 160 bits

17)Which of the following is not a common use of asymmetric cryptography? Select one: a. Digital signatures b. Key distribution c. Certicates d. Protection of real time streaming data

18) Public key cryptography requires participants to share secret keys Select one: a. False b. True

19) The security of Die-Hellman relies on the computational diculty of ___________ Select one: a. Discrete modular problem b. Distributed modular problem c. Distributed log problem (DLP) d. Discrete log problem

20) Which of the following is not a security service? Select one: a. Condentiality b. Integrity c. None of the options d. Nonrepudiation e. Message/user authentication