1. During decryption, we use the Inverse Initial Permutation (IP-1) before the IP.

a) True

b) False

### View Answer

2. A preferable cryptographic algorithm should have a good avalanche effect.

a) True

b) False

### View Answer

3. The number of tests required to break the DES algorithm are

a) 2.8×10^{14}

b) 4.2×10^{9}

c) 1.84×10^{19}

d) 7.2×10^{16}

### View Answer

^{56}keys =7.2×10

^{16}.

4. The number of tests required to break the Double DES algorithm are

a) 2112

b) 2111

c) 2128

d) 2119

### View Answer

5. How many keys does the Triple DES algorithm use?

a) 2

b) 3

c) 2 or 3

d) 3 or 4

### View Answer

6. In triple DES, the key size is ___ and meet in the middle attack takes ___ tests to break the key.

a) 2192 ,2112

b) 2184,2111

c) 2168,2111

d) 2168,2112

### View Answer

7. Using Differential Crypt-analysis, the minimum computations required to decipher the DES algorithm is

a) 2^{56}

b) 2^{43}

c) 2^{55}

d) 2^{47}

### View Answer

^{47}computations to decipher the DES algorithm.

8.Using Linear Crypt-analysis, the minimum computations required to decipher the DES algorithm is

a) 2^{48}

b) 2^{43}

c) 2^{56}

d) 2^{64}

### View Answer

^{43}computations to decipher the DES algorithm.